目录
1.基本操作（源代码）：
1.1
import javax.swing.JOptionPane; //导入JOptionPane类
public class Java_1 {
public static void main( String args[] )
{
//*********Found********
JOptionPane.showMessageDialog(
null, "欢迎\n你\n参加\nJava\n考试!" );
System.exit( 0 ); // 结束程序
}
}
/* JOptionPane类的常用静态方法如下：
showInputDialog()
showConfirmDialog()
showMessageDialog()
showOptionDialog()
*/
1.2
//*********Found********
import java.applet.*;
import java.awt.Graphics;
//*********Found********
public class Java_1 extends Applet {
public void paint( Graphics g )
{
//*********Found********
g.drawString( "欢迎你来参加Java 语言考试!", 25, 25 );
}
}
1.3
import java.applet.*;
import java.awt.Graphics;
//*********Found********
public class Java_1 extends Applet{
public void paint( Graphics g )
{
//*********Found********
g.drawString( "欢迎你来参加Java 语言考试!", 25, 25 );
}
}
1.4
//*********Found**********
public class Java_1{
public static void main(String args[]) {
byte b = 10; // 二进制表示00001010
//*********Found**********
**byte c = 0X000f;**
b = (byte)(b ^ c);
//*********Found**********
System.out.println("b的结果是：" +b);
}
}
1.5
public class Java_1{
//*********Found**********
public static void main(String args[]){
String string="现在学习如何访问一个字符串";
System.out.println("字符串 \""+string+"\"");
//*********Found**********
System.out.println("字符串长度："+string.length());
//*********Found**********
System.out.println("其中第7个字符是："+string.charAt(6));
char sub[] = new char[20];
System.out.print("从字节数组的第7到12获取字符是：");
string.getChars(6,12,sub,0);
System.out.println(sub);
}
}
1.6
public class Java_1{
//*********Found**********
public static void main(String args[]){
String string="现在学习如何访问一个字符串";
System.out.println("字符串 \""+string+"\"");
//*********Found**********
System.out.println("字符串长度："+string.length());
//*********Found**********
System.out.println("其中第7个字符是："+string.charAt(6));
char sub[] = new char[20];
System.out.print("从字节数组的第7到12获取字符是：");
string.getChars(6,12,sub,0);
System.out.println(sub);
}
}
1.7
import java.io.*;
public class Java_1{
public static void main(String[] args) {
int[] anArray; //声明一个整数型数组
//*********Found**********
anArray = new int[10]; //创建一个整数数组对象s
//*********Found**********
for (int i = 0; i < anArray.length;i++) { //对数组中每个元素赋值并显示
anArray[i] = i;
//*********Found**********
System.out.print(i+ " ");
}
System.out.println();
}
}
1.8
//*********Found**********
import java.io.*;
public class Java_1{
//*********Found**********
public static void main(String[] args) throws Exception{
InputStreamReader ir;
BufferedReader in;
ir=new InputStreamReader(System.in);
in=new BufferedReader(ir);
System.out.println("输入年份是:");
//*********Found**********
String s=in.readLine();
//*********Found**********
int year=Integer.parseInt(s);
if(year%4==0&&year%100!=0||year%400==0){
System.out.println(""+year+"年是闰年.");
}
else{
System.out.println(""+year+"年不是闰年.");
}
}
}
1.9
//*********Found**********
import java.io.*;
public class Java_1 {
public static void main(String[ ] args) throws IOException {
InputStreamReader ir;
BufferedReader in;
int sum, x;
String data;
//*********Found**********
sum = 0;
ir = new InputStreamReader(System.in);
in = new BufferedReader(ir);
System.out.println("请输入5个整数：");
//*********Found**********
for (int i = 1; i<=5; i++) {
data = in.readLine();
x = Integer.parseInt(data);
//*********Found**********
if (x%2==0)
sum += x;
}
System.out.println("偶数之和为"+ sum );
}
}
1.10
import java.io.*;
public class Java_1 {
public static void main(String[ ] args) throws IOException {
InputStreamReader ir;
BufferedReader in;
int max, x;
String data;
max = 0;
ir = new InputStreamReader(System.in);
in = new BufferedReader(ir);
System.out.println("请输入5个正整数：");
//*********Found**********
for (int i = 1; i <=5; i++) {
data = in.readLine();
//*********Found**********
x = Integer.parseInt (data);
if ( max < x )
//*********Found**********
max = x;
}
System.out.println("输入的最大值是 "+ max);
}
}
1.11
public class Java_1{
public static void main(String[] args){
//*********Found**********
int[] scores = {90,80,75,67,53};
int best = 0;
char grade;
// 找出这组成绩中的最高分
//*********Found**********
for (int i=0;i<5; i++){
//*********Found**********
if (scores[i]>best)
best = scores[i];
}
//求各分数的等级并显示
for (int i=0; i<scores.length; i++){
if (scores[i] >= best - 10)
grade = 'A';
//*********Found**********
else if(scores[i] >= best - 20)
grade = 'B';
else if (scores[i] >= best - 30)
grade = 'C';
else if (scores[i] >= best - 40)
grade = 'D';
else
grade = 'F';
System.out.println("Student " + i + " score is " + scores[i] +
" and grade is " + grade);
}
}
}
1.12
//*********Found**********
public class Java_1{
public static void main(String[] args){
int []a = {1,2,3,4,5,6,7,8};
int []b = {0,1,2,3,4,5,6,7};
int []c = new int[8];
int s=0;
//*********Found**********
for(int i=0;i<a.length;i++)
c[i]=a[i]+b[i];
for(int j=c.length-1;j>=0;j--)
//*********Found**********
s=s+c[j];
//*********Found**********
System.out.println("s="+s);
}
}
1.13
class MethodOverloading {
void receive(int i) {
System.out.println("Receive one int data");
System.out.println("i=" + i);
}
//*********Found**********
void receive(int x, int y) {
System.out.println("Receive two int data");
System.out.println("x=" + x + " y =" + y);
}
//*********Found**********
void receive(double d) {
System.out.println("Receive one double data");
System.out.println("d=" + d);
}
//*********Found**********
void receive(String s) {
System.out.println("Receive a string");
System.out.println("s="+s);
}
}
public class Java_1 {
public static void main(String args[]) {
MethodOverloading mo = new MethodOverloading();
mo.receive(1);
mo.receive(2, 3);
mo.receive(12.56);
mo.receive("very interesting, is not it?");
}
}
1.14
public class Java_1 {
public static void main(String[] args) {
//*********Found**********
for (int i=1;i<=5;i++){
for(int k=1;k<=5-i;k++)
//*********Found**********
System.out.print(" ");
//*********Found**********
for(int j = 1;j<=2*i-1;j++)
System.out.print("*");
//*********Found**********
System.out.println();
}
}
}
`
1.15
public class Java_1 {
public static void main(String[] args) {
int a,x = 2008;
//*********Found**********
System.out.print( x +"->" );
while( x != 0 ){
//*********Found**********
a = x%10;
System.out.print(a);
//*********Found**********
x = x/10;
}
}
}
1.16
public class Java_1 {
public static void main(String args[]) {
int a[][] = {{2, 3, 4}, {4, 6, 5}};
int b[][] = {{1, 5, 2, 8}, {5, 9, 10, -3}, {2, 7, -5, -18}};
int c[][] = new int[2][4];
for (int i = 0; i < 2; i++) {
for (int j = 0; j < 4; j++) {
//*********Found********
c[i][j] =0 ;
//*********Found********
for (int k = 0; k < 3; k++)
//*********Found********
c[i][j] += a[i][k]*b[k][j];
System.out.print(c[i][j] + " ");
}
System.out.println();
}
}
}
1.17
public class Java_1{
public static void main(String[] args){
//*********Found********
int[] ages = {35,43,28,39,62,57,48,29,54,46};
int sum = 0, avg = 0;
int tt = 0,fot = 0,fit = 0,st = 0;
for (int i=0; i<ages.length; i++){
if (ages[i] <=40 )
tt++;
else if (ages[i] >40 && ages[i]<=50)
fot++;
else if (ages[i] >50 && ages[i]<=60)
//*********Found********
fit++;
else
st++;
}
//*********Found********
for (int i = 0; i<ages.length; i++)
//*********Found********
sum += ages[i];
avg = sum/ages.length;
System.out.println("<=40: "+tt+" 41-50: " +fot+" 51-60: "
+ fit +" >=61: " + st);
}
}
1.18
public class Java_1 {
//*********Found********
public static void main(String args[]) {
int arr[][] = {{1, 2, 3, 4, 5}, {6, 7, 8, 9, 10}, {11, 12, 13, 14, 15}, {16, 17, 18, 19, 20}, {21, 22, 23, 24, 25}};
//*********Found********
int i, j, sum=0;
for (i = 0; i < 5; i++)
for (j = 0; j < 5; j++)
//*********Found********
if (i+j==4)
sum += arr[i][j];
System.out.println(sum);
}
}
`
1.19
public class Java_1 {
public static void main(String[] args) {
int []a = {5,9,2,8,7};
int max = 0;
int k = 0,t ;
for(int i=0;i<5;i++){
//*********Found********
if (a[i]%2==0 && max < a[i]){
max = a[i];
//*********Found********
k=i;
}
}
t = a[0];
a[0] = a[k];
a[k] = t;
//*********Found********
for(int i=0;i<a.length;i++)
System.out.print(a[i] + " ");
}
}
1.20
public class Java_1 {
public static void main(String[] args) {
//*********Found********
`int []f= new int[10];`
f[0]=f[1]=1;
//*********Found********
`for (int i=2;i<10;i++)`
f[i]=f[i-1]+f[i-2];
//*********Found********
`for (int i=0;i<f.length;i++)`
//*********Found********
`System.out.print(f[i]+" ");`
}
}
1.21
import javax.swing.JOptionPane;
public class Java_1 {
public static void main( String args[] ){
//变量初始化
int passes = 0, //考生通过的数目
failures = 0, //考生不通过的数目
student = 1, //学生计数器
result; //一门考生结果
String input, //用户输入的值
output; //输出字符串
//处理10名学生,用计数器控制循环
while ( student <= 10 ) {
input = JOptionPane.showInputDialog(
"输入结果(1=通过,2=不通过)" );
//*********Found**********
result = Integer.parseInt( input );
if ( result == 1 )
passes = passes + 1;
else
failures = failures + 1;
student = student + 1;
}
//结果处理
output = "通过: " + passes +
"\n不通过: " + failures;
if( passes > 8 )
output = output + "\n提高学费";
//*********Found**********
JOptionPane.showMessageDialog( null, output,
"对考试结果的分析示例",
JOptionPane.INFORMATION_MESSAGE );
//*********Found**********
System.exit( 0 );
}
}
1.22
public class Java_1 extends TT
{
//*********Found**********
`public static void main(String args[])`
{
Java_1 t = new Java_1("小龙");
}
public Java_1(String s)
{
super(s);
System.out.println("您好吗？");
}
public Java_1()
{
this("我是文朋");
}
}
class TT
{
public TT()
{
System.out.println("多高兴啊!");
}
public TT(String s)
{
//*********Found**********
`this();`
System.out.println("我是"+s);
}
}
1.23
public class Java_1
{
//*********Found**********
public static void main (String args[])
{
new SimpleThread("第1").start();
new SimpleThread("第2").start();
}
}
//*********Found**********
class SimpleThread extends Thread
{
public SimpleThread(String str)
{
super(str);
}
public void run()
{
for (int i = 0; i < 5; i++)
{
//*********Found**********
System.out.println(i + " " + getName());
try
{
sleep((int)(2 * 100));
}
catch (InterruptedException e) { }
}
System.out.println("运行! " + getName());
}
}
1.24
//*********Found**********
import javax.swing.*;
public class Java_1
{
//*********Found**********
public static void main(String[] args)
{
System.out.println();
System.out.println("这是一个指定球半径，求球体积的程序。");
String input=JOptionPane.showInputDialog("请输入球半径。");
//*********Found**********
double r=Double.parseDouble(input);
System.out.println("当球的半径是" + r + "时，该球的体积是 " + (Math.PI*r*r*r*4/3));
System.exit(0);
}
}
1.25
// 阅读下列代码：
public class Java_1
{
//*********Found**********
public static void main(String []args)
{
String s1=new String("你正在考试");
String s2=new String("你正在考试");
System.out.println(s1==s2);
//*********Found**********
System.out.println(s1.equals(s2));
}
}
1.26
public class Java_1
{
//*********Found**********
public static void main(String []args)
{
char ch='d';
//*********Found**********
switch(ch)
{
case 'a': System.out.print("a");break;
case 'b': System.out.print("b");
case 'c': System.out.print("c");break;
//*********Found**********
default : System.out.print("abc");
}
}
}
`
1.27
public class Java_1
{
public static void main(String[] args)
{
long sum;
//*********Found**********
sum =0;
for(int i=1;i<8;i+=2){
long b=1;
//*********Found**********
for(int j=1; j<=i; j++)
//*********Found**********
b = b * j;
System.out.println( i + "!= " + b);
sum+=b;
}
System.out.println("sum=" + sum);
}
}
1.28
public class Java_1 {
public static void main(String args[]) {
int x,n;
//*********Found********
n =0;
for( x = 100 ; x <= 200 ; x++)
if ( x % 9 == 0 ) {
//*********Found********
System.out.print(" " + x);
n++;
//*********Found********
if ( n%5 ==0) System.out.println( );
}
}
}
1.29
public class Java_1
{
public static void main(String args[])
{
int i,count;
//*********Found********
count =0;
for( i=100 ; i <= 200 ; i++)
//*********Found********
if ( i%3==0 ) count++;
//*********Found********
System.out.println("Count = " + count);
}
}
1.30
//Interest.java
//计算复杂利息
import java.text.DecimalFormat;
import javax.swing.JOptionPane;
import javax.swing.JTextArea;
public class Java_1{
public static void main( String args[] ){
double amount, principal = 1000.0, rate = .05;
DecimalFormat precisionTwo = new DecimalFormat( "0.00" );
//*********Found**********
JTextArea outputTextArea = new JTextArea( 11, 20 );
outputTextArea.append( "年\t存款总计\n" );
for ( int year = 1; year <= 10; year++ ) {
amount = principal * Math.pow( 1.0 + rate, year );
outputTextArea.append( year + "\t" +
//*********Found**********
precisionTwo.format( amount ) + "\n" );
}
//*********Found**********
JOptionPane.showMessageDialog(
null, outputTextArea, "复合利息",
JOptionPane.INFORMATION_MESSAGE );
System.exit( 0 );
}
}
1.31
import javax.swing.JOptionPane;
public class Java_1{
//*********Found**********
public static void main( String args[] ){
PackageData d = new PackageData();
String output;
output = "实例化后:\n" + d.toString();
d.x = 77; //修改包访问的数据
//*********Found**********
d.s = "祝您成功!"; //修改包访问的数据
output += "\n修改数据后的访问结果:\n" + d.toString();
//*********Found**********
JOptionPane.showMessageDialog( null, output,
"对包的访问示范",
JOptionPane.INFORMATION_MESSAGE );
System.exit( 0 );
}
}
class PackageData {
int x; //访问包的实例变量
String s; //访问包的实例变量
//构造方法
public PackageData(){
x = 0;
s = "Hello";
}
public String toString(){
return "x: " + x + " s: " + s;
}
}
1.32
import javax.swing.*;
import java.text.DecimalFormat;
public class Java_1{
//*********Found**********
public static void main( String args[] ){
SimpleTime t = new SimpleTime( 12, 30, 19 );
//*********Found**********
JOptionPane.showMessageDialog( null, t.buildString(),
" \"this\" 引用示范",
JOptionPane.INFORMATION_MESSAGE );
System.exit( 0 );
}
}
class SimpleTime {
private int hour, minute, second;
public SimpleTime( int hour, int minute, int second ){
this.hour = hour;
this.minute = minute;
this.second = second;
}
public String buildString(){
//*********Found**********
return "this.toString(): " + toString() +
"\ntoString(): " + toString() +
"\nthis (with implicit toString() call): " +
this;
}
public String toString(){
DecimalFormat twoDigits = new DecimalFormat( "00" );
return twoDigits.format( this.hour ) + ":" +
twoDigits.format( this.minute ) + ":" +
twoDigits.format( this.second );
}
}
1.33
import java.io.*;
public class Java_1 {
public static void main(String[] args) {
char[] charArray = {'a','b','c','d','e','f','g','h','i'};
char c ;
try{
//*********Found**********
DataOutputStream out = new DataOutputStream(
new FileOutputStream("test.dat"));
for(int i =0; i<charArray.length; i++){
out.writeChar(charArray[i]);
}
out.close();
DataInputStream in = new DataInputStream(
//*********Found**********
new FileInputStream("test.dat"));
while(in.available() != 0){
c=in.readChar();
System.out.print(c+" ");
}
System.out.println();
//*********Found**********
in.close();
}catch(IOException e){}
}
}
1.34
//用2至20的偶数去初始化数组
import javax.swing.*;
public class Java_1{
public static void main( String args[] ){
final int ARRAY_SIZE = 10;
int n[]; //引用整形数组
String output = "";
//*********Found*********
n = new int[ ARRAY_SIZE ]; //分配数组
//给数组赋值
for ( int i = 0; i < n.length; i++ )
n[ i ] = 2 + 2 * i;
output += "数组下标\t值\n";
for ( int i = 0; i < n.length; i++ )
output += i + "\t" + n[ i ] + "\n";
//*********Found**********
JTextArea outputArea = new JTextArea( 11, 10 );
outputArea.setText( output );
//*********Found**********
JOptionPane.showMessageDialog( null, outputArea,
"用2至20的偶数去初始化数组",
JOptionPane.INFORMATION_MESSAGE );
System.exit( 0 );
}
}
1.35
public class Java_1{
void equalsMethod1(){
//*********Found**********
String s1= "how are you";
//*********Found**********
char[] s2={'h','o','w',' ','a','r','e',' ','y','o','u'};
//*********Found**********
System.out.println(s1==s2.toString());
}
public static void main(String args[]){
Java_1 OperAndExp=new Java_1();
OperAndExp.equalsMethod1();
}
}
1.36
import java.io.*;
public class Java_1
{
public static void main(String args[])
{
int a=15,b=25,c=5,m;
if(a>b){
//*********Found**********
if(b>c)
m=b;
else
//*********Found**********
m=(a>c)? c:a;
}else{
if(a>c)
//*********Found**********
m =a;
else
m=(b>c)? c:b;
}
//*********Found**********
System.out.println("median = " + m);
}
}
1.37
import javax.swing.*;
public class Java_1{
public static void main( String args[] ){
//*********Found**********
StringBuffer buf = new StringBuffer( "Hello, how are you?" );
String output = "buf = " + buf.toString() +
"\nlength = " + buf.length() +
"\ncapacity = " + buf.capacity();
buf.ensureCapacity( 75 );
output += "\n\nNew capacity = " + buf.capacity();
buf.setLength( 10 );
//*********Found**********
output+= "\n\nNew length = " + buf.length() +
"\nbuf = " + buf.toString();
JOptionPane.showMessageDialog( null, output,
"字符串缓存长度和容量的实例",
//*********Found**********
JOptionPane.INFORMATION_MESSAGE );
//*********Found**********
System.exit( 0 );
}
}
`
1.38
public class Java_1
{
//*********Found**********
public static void main(String args[])
{
byte b = 8;
//*********Found**********
long g = 567L;
float f = 3.1415f;
double d = 2.789;
int ii = 207;
//*********Found**********
long gg = g+ii;
float ff = b*f;
double dd = ff/ii+d;
//*********Found**********
System.out.print("ii= "+ii+" ");
System.out.println("gg= "+gg);
System.out.println("ff= "+ff);
System.out.println("dd= "+dd);
}
}
`
1.39
import javax.swing.JOptionPane;
public class Java_1{
public static void main( String args[] ){
int x, result;
String xVal;
//*********Found**********
xVal = JOptionPane.showInputDialog(
"输入1个整数:" );
//*********Found**********
x = Integer.parseInt( xVal );
//*********Found**********
result = x*x;
JOptionPane.showMessageDialog(null,
"该数的平方是" + result );
System.exit( 0 );
}
}
`
1.40
public class Java_1 {
public static void main(String[] args) {
int i, k, n;
//*********Found********
n= 0;
//*********Found********
for (i = 0; i<10; i++) {
k = i * 10 + 6;
//*********Found********
if ( k%3==0) {
System.out.print(k + " ");
n++;
}
}
System.out.println("\n" + "The number is " + n + ".");
}
}
1.41
public class Java_1{
public static void main(String[] args){
//**************found*****************
int[] arrayOfInts = { 33, 88, 5, 458, 18, 107, 200, 8, 622, 127 };
int searchfor = 18;
int i = 0;
//**************found*****************
boolean foundIt = false;
for ( ; i<arrayOfInts.length; i++){
//**************found*****************
if (arrayOfInts[i] == searchfor ){
foundIt = true;
//**************found*****************
break;
}
}
if (foundIt) {
System.out.println("Found " + searchfor + " at index " + i);
} else {
System.out.println(searchfor + "not in the array");
}
}
}
1.42
import java.lang.*;
import java.util.*;
public class Java_1 {
public static void main(String[] args){
int n;
double e = 1.0;
System.out.print("请输入n: ");
//***************************Found*********************
`Scanner scan = new Scanner (System.in);`
String nstr = scan.next();
//***************************Found*********************
`n = Integer.parseInt(nstr);`
double t = 1.0;
for(int i=1;i<=n;i++){
//***************************Found*********************
`t = t/i;`
e = e + t;
}
System.out.print("e 的近似值为： "+e);
}
}
1.43
public class Java_1 {
public static void main(String[] args) {
//**********found**********
char[] arrayOfChars = { 'A', 'B', 'A','D', 'E','F','G' };
char searchfor = 'A';
int i=0, j=0;
//**********found**********
while ( i < arrayOfChars.length) {
if (arrayOfChars[i] == searchfor) {
System.out.println("Found " + searchfor + " at index " + i);
j++;
}
//**********found**********
i++;
}
//**********found**********
if (j>0) {
System.out.println("The total amount of " + searchfor + " is " + j );
} else {
System.out.println(searchfor + " is not in the array");
}
}
}
1.44
import java.util.*;
import java.io.*;
public class Java_1 {
//**********found**********
`static long sum =0;`
public static void main(String[] args) {
//**********found**********
`for (int counter=0 ; counter <= 10; counter++){`
System.out.printf("%d! = %d\n", counter, factorial(counter));
sum=sum+factorial(counter);
}
System.out.println("sum="+sum);
}
//**********found**********
`public static long factorial(long number ) {`
if (number <= 1)
return 1;
else
return number * factorial(number - 1);
}
}
1.45
import java.lang.*;
import java.util.*;
public class Java_1 {
public static void main(String [] args){
System.out.print("请输入n: ");
//**********Found**********
`Scanner scan = new Scanner (System.in);`
String nstr = scan.next();
//**********Found**********
`int n = Integer.parseInt(nstr);`
int b = 6;
long sum=0,item=b;
for(int i=1;i<=n;i++){
sum += item;
//**********Found**********
`item = item * 10 + b;`
}
System.out.print(n + "项的和为 " + sum);
}
}
1.46
import java.io.*;
import java.util.*;
public class Java_1 {
static int number=4;
//**********Found**********
static int[] t1 = new int[number];
public static void main(String[] args) {
Java_1 work=new Java_1();
//**********Found**********
work.sort();
}
void sort(){
System.out.println("请输入4个数：");
//**********Found**********
Scanner in_t1 = new Scanner(System.in);
for(int i=0;i<number;i++){
t1[i]=in_t1.nextInt();
}
for (int i = 0; i < t1.length; i++) {
int pos = i;
for (int j = i + 1; j < t1.length; j++) {
//**********Found**********
if (t1[pos] > t1[j])
pos = j;
}
if (pos != i) {
t1[i] = t1[i] + t1[pos];
t1[pos] = t1[i] - t1[pos];
t1[i] = t1[i] - t1[pos];
}
}
for (int i = 0; i <= t1.length - 1; i++)
System.out.print(t1[i] + "\t");
}
}
1.47
public class Java_1{
public static void main(String[] args){
//**********Found**********
int[] grades = {62,53,84,77,65,85,91,94,61,78,86,88};
int sum=0, avg = 0;
int stus=0;
int a=0,b=0,c=0,d=0,e=0;
//**********Found**********
for (int i=0; i<grades.length; i++){
if (grades[i] <60 )
e++;
else if (grades[i] >=60 && grades[i]<=69)
d++;
else if (grades[i] >=70 && grades[i]<=79)
c++;
else if (grades[i] >=80 && grades[i]<=89)
b++;
else
a++;
//**********Found**********
sum+= grades[i];
}
//**********Found**********
stus =grades.length;
//**********Found**********
avg = sum/stus;
System.out.println(">=90: "+a+"; 80-89: " +b+"; 70-79: "
+ c +"; 60-69: " + d+"; <60: "+e);
System.out.println(stus+" students, and the average is : "+avg);
}
}
1.48
import java.util.*;
public class Java_1 {
public static void main(String [] args) {
int n;
//***************************Found*********************
Scanner scan=new Scanner ( System.in);
String nstr=scan.next();
scan.close();
//***************************Found*********************
n= Integer.parseInt(nstr);
int[][] mat=new int[n][n];
for( int i=0;i<n;i++)
for( int j=0;j<n;j++)
mat[i][j]=(int)(Math.random()*101);
for( int i=0;i<n;i++) {
for( int j=0;j<n;j++)
System.out.print(mat[i][j]+" ");
//***************************Found*********************
System.out.println();
}
int diagSum=0;
for(int i=0;i<n;i++)
//***************************Found*********************
diagSum+=mat[i][i];
System.out.print("主对角线值的和为： "+diagSum);
}
}
1.49（star）
public class Java_1 {
public static void main(String[] args) {
int i, j, k, t;
int[] m = {10, 21, 123, 5, 94};
for (i = 0; i < m.length - 1; i++) {
//**********Found**********
k = i;
//**********Found**********
for (j = i+1; j < m.length; j++) {
//**********Found**********
if ( m[k]%10 > m[j]%10 ) {
k = j;
}
}
if (k != i) {
t = m[i];
//**********Found**********
m[i]=m[k];
m[k] = t;
}
}
//**********Found**********
for (i = 0; i < m.length; i++) {
System.out.print(" " + m[i]);
}
System.out.println();
}
}
1.50
public class Java_1 {
public static void main(String[] args) {
int i, j, a, b;
int[][] m = {{1, 2, 3}, {1, 2, 3, 4}, {1, 2, 4, 300, 5}, {3, 5, 6, 8, 10, 9}};
a = 0;
//**********Found**********
b = 0;
//**********Found**********
for (i = 0; i < 4; i++) {
//**********Found**********
for (j = 0; j <m[i].length; j++) {
//**********Found**********
if ( m[a][b] < m[i][j]) {
a = i;
b = j;
}
}
}
//**********Found**********
System.out.println("max=" + m[a][b] + ",row=" + a + ",col=" + b);
}
}
1.51
public class Java_1 {
public static void main(String[] args) {
int[] scores = {82, 75, 42, 92, 85, 78, 93, 65};
int i;
int sum = scores[0];
//**********Found**********
int max = 0;
//**********Found**********
for (i = 1; i < scores.length; i++) {
//**********Found**********
sum += scores[i];
if (max < scores[i] ) {
max = scores[i];
}
}
//**********Found**********
System.out.println("平均值：" + (float)sum/ i);
System.out.println("最大值：" + max);
}
}
1.52（star）
import java.util.*;
public class Java_1{
public static void main(String[] args){
int[] a = new int[15];
int i, j, k;
int[][] b = new int[5][];
for (i = 0; i < b.length; i++)
//**********Found**********
b[i] = new int[i+1];
//**********Found**********
Scanner scan = new Scanner(System.in);
for (i = 0; i < a.length; i++)
//**********Found**********
a[i] = scan.nextInt();
k = 0;
for (i = 0; i < b.length; i++) {
//**********Found**********
for (j = 0; j <b[i].length; j++) {
//**********Found**********
b[i][j] = a[k++];
System.out.print(String.format("%5d",b[i][j]));
}
System.out.println();
}
}
}
1.53
public class Java_1 {
public static void main(String args[]) {
int a = 3, d = 4;
//**********Found**********
int s = a;
//**********Found**********
for (int i = 1; i <= 9;i++) {
//**********Found**********
a = a+d;
//**********Found**********
s += a;
}
System.out.println("前十项的和为 " + s);
}
}
1.54
import java.util.Scanner;
public class Java_1 {
public static void main(String[] args) {
int []a = new int[10];
int s = 0,n = 0;
//**********Found**********
Scanner scan = new Scanner(System.in);
//**********Found**********
for(int i=0;i<a.length;i++){
//**********Found**********
a[i] = scan.nextInt();
if(a[i]%2==0){
//**********Found**********
s += a[i];
//**********Found**********
n = n+1;
}
}
if(n!=0)
System.out.println("偶数的平均值是 " + s/n);
}
}
1.55
//*********Found********
import javax.swing.*;
public class Java_1{
public static void main( String args[] ){
String s1 = new String( "您好! " ),
s2 = new String( "祝您生日快乐!" ),
output;
//*********Found********
output = "s1 = " + s1 + "\ns2 = " + s2;
//*********Found********
output += "\n\n s1.concat( s2 ) = " + s1.concat( s2 );
output += "\ns1 连接前= " + s1;
//*********Found********
JOptionPane.showMessageDialog( null, output,
"显示字符串连接",
JOptionPane.INFORMATION_MESSAGE );
System.exit( 0 );
}
}
1.56
public class Java_1{
public static void main(String[] args){
int[] a ={1,2,3,4,5,6,7,8,9,10};
//**********Found**********
int[][] b = new int[2][5];
int i,j,k;
j=k=0;
//**********Found**********
for(i=0;i<a.length;i++)
//**********Found**********
if(a[i]%2 == 1)
//**********Found**********
b[0][j++] = a[i];
else
//**********Found**********
b[1][k++] = a[i];
for(i=0;i<2;i++){
for(j=0;j<b[i].length;j++)
System.out.print(" " + b[i][j] );
System.out.println();
}
}
}
1.57
public class Java_1{
public static void main(String[] args){
int[][] b ={{1,2,3},{4,5,6}};
//**********Found**********
int[] a = new int[6];
int i,j,k=0;
//**********Found**********
for(j=0;j<3;j++)
for(i=0;i<2;i++){
//**********Found**********
a[k]=b[i][j];
//**********Found**********
k += 1;
}
//**********Found**********
for(k=0;k<a.length;k++)
System.out.print( a[k] + " ");
}
}
2.简单应用：
2.1
import java.util.Random;
public class Java_2
{
public static void main(String args[]){
Random random = new Random();
float x = random.nextFloat();//产生0.0与1.0之间的一个符点数
int n = Math.round(20*x); //构造20以内的一个整数
long f = 1 ; //保存阶乘的结果
int k = 1 ; //循环变量
//*********Found********
do{f* = k;
k++;
//*********Found********
}while(k<=n) ;
System.out.println(n+"!= "+f);
}
}
2.2
import java.awt.*;
import java.applet.*;
//*********Found********
public class Java_2 extends Applet
{
TextArea outputArea;
public void init()
{
setLayout(new BorderLayout());
outputArea = new TextArea();
//*********Found********
add( outputArea );
// 计算0至10的阶乘
for ( long i = 0; i <= 10; i++ )
//*********Found********
outputArea.append(i + "! = " + factorial(i) + "\n" );
}
// 用递归定义阶乘方法
public long factorial( long number )
{
if ( number <= 1 ) // 基本情况
return 1;
else
//*********Found********
return number * factorial( number- 1 );
}
}
2.3
public class Java_2
{
public static void main(String[] args) {
int[][] aMatrix = {{1,1,1,1,1},{2,2,2,2,2},{3,3,3,3,3},{4,4,4,4,4}};
int i = 0; //循环变量
int j = 0; //循环变量
//print matrix
for (i = 0; i < aMatrix.length; i++) {
//*********Found********
for ( j = 0; j < aMatrix[i].length; j++) {
//*********Found********
System.out.print(aMatrix[i][j] + " ");
}
System.out.println();
}
}
}
2.4
//*********Found**********
public class Java_2 extends Thread{
private int x=0;
private int y=0;
public static void main(String[]args){
Java_2 r = new Java_2();
//*********Found**********
Thread t = new Thread(r);
t.start();
}
public void run() {
//*********Found**********
int k = 0;
for(;;){
x++;
//*********Found**********
y++;
k++;
if (k>5) break;
System.out.println("x=" + x + ",y ="+ y);
}
}
}
2.5
public class Java_2 {
public static void main (String args[]) {
try {
Sleep a = new Sleep ();
Thread t = new Thread (a);
//*********Found**********
t.start();
t.join();
int j= a.i;
System.out.println("j="+j+",a.i="+a.i);
} catch (Exception e) {}
}
}
//*********Found**********
class Sleep implements Runnable{
int i;
public void run () {
try {
//*********Found**********
Thread.sleep(50);
i= 10;
}
//*********Found**********
catch(InterruptedException e) {}
}
}
2.6
public class Java_2{
public static void main(String args[]) {
//*********Found**********
int a[][] =new int[5][5];
int i,j,k = 1;
for(i=0;i<5;i++)
for(j=0;j<5;j++)
if((i+j)<5){
a[i][j] = k;
//*********Found**********
k++;
if (k > 9) k = 1;
}else
//*********Found**********
a[i][j]=0;
for(i=0;i<5;i++){
for(j=0;j<5;j++)
System.out.print(a[i][j]+ " ");
//*********Found**********
System.out.println();
}
}
}
2.7
import java.io.*;
public class Java_2{
public static void main (String[] args){
//*********Found**********
byte buf[] = new byte[5];
int len= 0 ,c1 = 0,c2=0;
//*********Found**********
try{
//*********Found**********
FileInputStream in = new FileInputStream("test.txt");
while((len =in.read(buf,0,5))>0){
for(int i = 0; i < len;i++)
if(buf[i]>= '0' && buf[i] <= '9'){
c1 ++;
}
else
if((buf[i]>= 'a' && buf[i] <= 'z') || buf[i]>= 'A' && buf[i] <= 'Z')
c2++;
if(len <5) break;
}
//*********Found**********
in.close();
}catch(Exception e ){}
System.out.println("数字数是 " + c1 + "，字母数是 " + c2);
}
}
2.8
import java.io.*;
public class Java_2{
public static void main(String args[]) {
int a[][] = new int[5][5];
int i,j,k=1;
for(i=0;i<5;i++)
//*********Found**********
for( j=0; j<5 ;j++ )
//*********Found**********
if((i+j)< 4)
a[i][j]=0;
else{
//*********Found**********
a[i][j]=k++;
}
for(i=0;i<5;i++){
for(j=0;j<5;j++)
//*********Found**********
if(a[i][j]<10)
System.out.print(a[i][j]+ " ");
else
System.out.print(a[i][j]+ " ");
System.out.println();
}
}
}
2.9
public class Java_2{
public static void main(String args[]){
int i=0;
String greetings[] ={ "Hello World!","Hello!","HELLO WORLD!!"};
while (i<4){
try{
//*********Found********
System.out.println(greetings[i]);
}
//*********Found********
catch(ArrayIndexOutOfBoundsException e){
//*********Found********
System.out.println("Catch " + e.getMessage());
System.out.println("Ending the print.");
}
finally{
System.out.println("---------------------");
}
//*********Found********
i++;
}
}
}
2.10
import java.io.File;
public class Java_2
{
public static void main(String s[])
{
//Getting the Current Working Directory
String curDir = System.getProperty("user.dir");
System.out.println("当前的工作目录是:"+curDir);
//*********Found**********
File ff=new File(curDir);
String[] files=ff.list();
for(int i=0; i<files.length; i++)
{
String ss=curDir+"\\"+files[i];
traverse(0,ss);
}
}
/**
* 递归地遍历目录树
* @param level 目录的层次
* @param s 当前目录路径名
*/
public static void traverse(int level,String s)
{
File f=new File(s);
for(int i=0; i<level; i++) System.out.print(" ");
if(f.isFile())
{
System.out.println(f.getName());
}
else if(f.isDirectory())
{
//*********Found**********
System.out.println("<"+f.getName()+">");
String[] files=f.list();
level++;
//*********Found**********
for(int i=0; i<files.length;i++)
{
String ss=s+"\\"+files[i];
//*********Found**********
traverse(level,ss);
}
}
else
{
System.out.println("ERROR!");
}
}
}
2.11
public class Java_2 {
public static void main(String[ ] args) {
Point pt;
//*********Found**********
pt = new Point(2, 3);
System.out.println(pt);
}
}
class Point {
//*********Found**********
private int x;
private int y;
//*********Found**********
public Point(int a, int b) {
x = a;
y = b;
}
int getX( ) {
return x;
}
int getY( ) {
return y;
}
void setX(int a) {
x = a;
}
void setY(int b) {
y = b;
}
//*********Found**********
public String toString ( ) {
return "( " + x + "," + y + " ) ";
}
}
2.12
public class Java_2 {
public static void main(String[ ] args) {
//*********Found**********
Point[] pt = new Point[2];
pt[0] = new Point();
pt[1] = new Point(2, 3);
//*********Found**********
for (int i=0; i < pt.length; i++) {
System.out.print( pt[i] );
}
}
}
class Point {
private int x;
private int y;
public Point() {
this(0, 0);
}
//*********Found**********
public Point (int a, int b) {
x = a;
y = b;
}
int getX( ) {
return x;
}
int getY( ) {
//*********Found**********
return y;
}
void setX(int a) {
x = a;
}
void setY(int b) {
y = b;
}
public String toString ( ) {
return " ( " + x + "," + y + " ) ";
}
}
2.13
public class Java_2 {
public static void main(String args[]) {
int [][]a = {{2, 3, 4}, {4, 6, 5}};
int [][]b = {{1, 5, 2, 8}, {5, 9, 10, -3}, {2, 7, -5, -18}};
//*********Found**********
int [][]c = new int[2][4];
for (int i = 0; i < 2; i++) {
//*********Found**********
for (int j = 0; j < 4; j++) {
//*********Found**********
c[i][j]=0;
for (int k = 0; k < 3; k++)
//*********Found**********
c[i][j] +=a[i][k]*b[k][j];
System.out.print(c[i][j] + " ");
}
System.out.println();
}
}
}
2.14
import java.io.*;
public class Java_2 {
public static void main(String[] args) {
ObjectOutputStream oos = null;
ObjectInputStream ois = null;
try {
File f = new File("Person.dat");
//*********Found**********
oos = new ObjectOutputStream(new FileOutputStream(f));
oos.writeObject(new Person("小王"));
oos.close();
ois = new ObjectInputStream(new FileInputStream(f));
//*********Found**********
Person d = (Person) ois.readObject();
System.out.println(d);
ois.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
//*********Found**********
class Person implements Serializable{
String name = null;
public Person(String s) {
name = s;
}
//*********Found**********
public String toString() {
return name;
}
}
2.15
//*********Found**********
public class Java_2 extends Thread{
private String sThreadName;
public static void main(String argv[]){
Java_2 first = new Java_2("first");
//*********Found**********
first.start();
Java_2 second = new Java_2("second");
//*********Found**********
second.start();
}
//*********Found**********
public Java_2(String s){
sThreadName = s;
}
public String getThreadName(){
return sThreadName;
}
public void run(){a
for(int i = 0; i < 4; i ++){
//*********Found**********
System.out.println(getThreadName()+i);
try{
Thread.sleep(100);
} catch(InterruptedException e){
System.out.println(e.getMessage());
}
}
}
}
2.16
public class Java_2{
public static void main(String args[]) {
SubClass subC = new SubClass();
subC.doSomething();
}
}
class SuperClass {
int x;
SuperClass() {
//*********Found********
x =3;
System.out.println("in SuperClass : x=" + x);
}
void doSomething() {
//*********Found********
System.out.println("in SuperClass.doSomething()");
}
}
class SubClass extends SuperClass {
int x;
SubClass() {
super();
//*********Found********
x =5;
System.out.println("in SubClass :x=" + x);
}
void doSomething() {
super.doSomething();
//*********Found********
System.out.println("in SubClass.doSomething()");
System.out.println("super.x=" + super.x + " sub.x=" + x);
}
}
2.17
//*********Found********
import java.awt.*;
import java.io.*;
import java.awt.event.* ;
import javax.swing.*;
//*********Found********
public class Java_2 implements ActionListener{
JTextArea ta;
JFrame f ;
JLabel label;
JButton bt;
public static void main(String args[ ]){
Java_2 t = new Java_2();
t.go();
}
void go(){
f = new JFrame("Save data");
label = new JLabel("请输入需要保存的文本：");
ta = new JTextArea(3,20);
bt = new JButton("保存");
//*********Found********
f.add(label,BorderLayout.NORTH);
f.add(ta,BorderLayout.CENTER);
f.add(bt,BorderLayout.SOUTH);
//*********Found********
bt.addActionListener(this);
f.setSize(400,400);
f.pack( );
f.setVisible(true) ;
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void actionPerformed(ActionEvent event){
try{
FileWriter out = new FileWriter("out.txt");
String str = ta.getText();
//*********Found********
out.write(str);
out.close();
} catch( Exception e){
}
}
}
2.18
import java.io.*;
public class Java_2 {
public static void main(String args[]) {
String ShowMes[] = {"在那山的那边海的那边有一群蓝精灵", "它们活泼又聪明它们调皮又灵敏", "它们自由自在生活在那绿色的大森林", "它们善良勇敢相互都欢喜！"};
try {
//*********Found********
FileWriter out = new FileWriter("test.txt");
BufferedWriter outBW = new BufferedWriter(out);
for (int i = 0; i < ShowMes.length; i++) {
outBW.write(ShowMes[i]);
outBW.newLine();
}
//*********Found********
outBW.close();
} catch (Exception e) {
e.printStackTrace();
}
try {
//*********Found********
FileReader in = new FileReader(new File("test.txt"));
BufferedReader inBR = new BufferedReader(in);
String stext = null;
int j = 1;
while ((stext = inBR.readLine()) != null) {
System.out.println("第" + j + "行内容：" + stext);
//*********Found********
j++;
}
inBR.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
2.19
import java.awt.*;
import java.awt.event.*;
import java.util.Vector;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.table.*;
//*********Found********
public class Java_2 implements ActionListener{
JTable table = null;
DefaultTableModel defaultModel = null;
//*********Found********
public Java_2(){
JFrame f = new JFrame();
String[] name = {"字段 1","字段 2","字段 3","字段 4","字段 5"};
String[][] data = new String[5][5];
int value =1;
for(int i=0; i<data.length; i++){
for(int j=0; j<data.length ; j++)
data[i][j] = String.valueOf(value++);
}
defaultModel = new DefaultTableModel(data,name);
table=new JTable(defaultModel);
table.setPreferredScrollableViewportSize(new Dimension(400, 80));
JScrollPane s = new JScrollPane(table);
JPanel panel = new JPanel();
JButton b = new JButton("增加行");
panel.add(b);
//*********Found********
b.addActionListener(this);
b = new JButton("删除行");
panel.add(b);
b.addActionListener(this);
//*********Found********
Container contentPane = f.getContentPane();
contentPane.add(panel, BorderLayout.NORTH);
contentPane.add(s, BorderLayout.CENTER);
//*********Found********
f.setTitle("增删表格行");
f.pack();
f.setVisible(true);
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
//*********Found********
table.addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
if(table.isCellSelected(table.getSelectedRow(), table.getSelectedColumn())){
int selRow=table.getSelectedRow();
int selCol=table.getSelectedColumn();
JOptionPane.showMessageDialog(null,
"位于 ("+selRow+","+selCol+")的元素： "+table.getValueAt(selRow,selCol),
"PLAIN_MESSAGE", JOptionPane.PLAIN_MESSAGE);
}
}
});
}
public void actionPerformed(ActionEvent e){
if(e.getActionCommand().equals("增加行"))
defaultModel.addRow(new Vector());
if(e.getActionCommand().equals("删除行")){
int rowcount = defaultModel.getRowCount()-1; //getRowCount返回行数，rowcount<0代表已经没有任何行了。
if(rowcount >= 0){
defaultModel.removeRow(rowcount);
defaultModel.setRowCount(rowcount);
}
}
table.revalidate();
}
public static void main(String[] args) {
new Java_2();
}
}
2.20
public class Java_2{
public static void main(String[] args){
//*********Found**********
int [][] aMatrix = new int[4][];
int i = 0;
int j = 0;
int k = 4;
for(i = 0; i < 4; i++){
//*********Found**********
aMatrix[i] = new int[k--];
//*********Found**********
for (j = 0; j < aMatrix[i].length; j++) {
aMatrix[i][j] = i+1;
System.out.print(aMatrix[i][j] + " ");
}
//*********Found**********
System.out.println();
}
}
}
2.21
import java.util.*;
public class Java_2
{
public static void main(String[] args)
{
Student[] java = new Student[3];
java[0] = new Student("李明", 80);
java[1] = new Student("赵冬", 75);
java[2] = new Student("王晓", 98);
//*********Found**********
Arrays.sort(java);
System.out.println("Java 成绩降序排序的结果是：");
for (int i = 0; i < java.length; i++)
{
Student e = java[i];
//*********Found**********
System.out.println("name=" + e.getName()
+ ",fenshu=" + e.getFenshu());
}
}
}
//*********Found**********
class Student implements Comparable
{
public Student(String n, double f)
{
name = n;
fenshu = f;
}
public String getName()
{
return name;
}
public double getFenshu()
{
return fenshu;
}
public int compareTo(Object otherObject)
{
Student other = (Student)otherObject;
if (fenshu < other.fenshu) return 1;
if (fenshu > other.fenshu) return -1;
return 0;
}
private String name;
//*********Found**********
private double fenshu;
}
2.22
public class Java_2
{
public static void main(String[] args)
{
System.out.println("观察triple方法参数 double 10.0 的改变：");
//*********Found**********
double canshu = 10;
//*********Found**********
System.out.println("参数*３前，参数值为 " +canshu);
triple(canshu);
System.out.println("在triple方法外，参数值仍为 " + canshu);
System.out.println("思考：方法能否改变参数值？");
}
//*********Found**********
public static void triple(double x)
{
//*********Found**********
x=3*x;
//*********Found**********
System.out.println("在triple方法内，参数 10 变为 " + x);
}
}
2.23
import java.text.*;
public class Java_2
{
public static void main(String[] args)
{
Person[] people = new Person[2];
people[0] = new Worker("老张", 30000);
people[1] = new Student("小王", "计算机科学");
for (int i = 0; i < people.length; i++)
{
Person p = people[i];
//*********Found**********
System.out.println(p.getName() + ", " + p.getDescription());
}
}
}
//*********Found**********
abstract class Person
{
public Person(String n)
{
name = n;
}
//*********Found**********
public abstract String getDescription();
public String getName()
{
return name;
}
private String name;
}
//*********Found**********
class Worker extends Person
{
public Worker(String n, double s)
{
super(n);
salary = s;
}
public String getDescription()
{
NumberFormat formatter = NumberFormat.getCurrencyInstance();
return "工人，年薪是 " + formatter.format(salary) + "。";
}
private double salary;
}
//*********Found**********
class Student extends Person
{
public Student(String n, String m)
{
super(n);
major = m;
}
public String getDescription()
{
return "学生，专业是 " + major + "。";
}
private String major;
}
2.24
public class Java_2
{
public static void main(String[] args)
{
Thread t = new SimpleThread("Testing_Thread");
//*********Found**********
t.start() ;
}
}
//*********Found**********
class SimpleThread extends Thread
{
public SimpleThread(String str)
{
//*********Found**********
super(str) ;
}
//*********Found**********
public void run()
{
System.out.println("Running the " + getName() + ":");
for (int i = 0; i < 5; i++)
{
System.out.println("---" + i + "---" + getName());
try
{
sleep((int)(2 * 100));
}
//*********Found**********
catch(InterruptedException e) { }
}
}
}
2.25
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
public class Java_2
{
public static void main(String args[])
{
if(args.length<2)
{
System.out.println("ERROR: need parameters.");
System.out.println("\n -usage: java <classname> <file1> <file2>");
System.exit(0);
}
File f1=new File(args[0]);
//*********Found**********
File f2=new File(args[1]);
try
{
//*********Found**********
FileReader fr=new FileReader(f2);
FileWriter fw=new FileWriter(f1,true);
int b;
//*********Found**********
while(( b=fr.read() ) != -1 ) fw.write(b);
fr.close();
fw.close();
}
catch(IOException e)
{
e.printStackTrace();
}
System.out.println("has done!");
//*********Found**********
if(f2.delete()) System.out.print("SUCCESS!");
}
}
2.26
//*********Found**********
import java.io.*;
import java.util.Vector;
public class Java_2
{
public static void main(String args[])
{
Vector v=new Vector();
try
{
//*********Found**********
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
String str = "";
System.out.println("请输入用户和密码信息，中间用空格隔开，输入quit退出:");
//*********Found**********
while (!(str.equals("quit")||str.equals("QUIT")))
{
str = in.readLine();
if(isValid(str))
v.add(str);
else
{
if(!(str.equals("quit")||str.equals("QUIT")))
System.out.println("The string is NOT valid!");
}
}
System.out.println("请输入保存到的文件名:");
str=in.readLine();
String curDir = System.getProperty("user.dir");
File savedfile=new File(curDir+"\\"+ str );
BufferedWriter out = new BufferedWriter(new FileWriter(savedfile));
for(int i=0; i<v.size(); i++)
{
String tmp=(String)v.elementAt(i);
//*********Found**********
out.write(tmp);
out.write("\n");
}
out.close();
}
catch (Exception e)
{
System.out.print("ERROR:"+e.getMessage());
}
}
/**
* 判定输入的字符串是否符合规范
* @param s 输入的待校验的字符串
* @return 校验的结果，正确则返回为真
*/
public static boolean isValid(String s)
{
if(s.indexOf(" ")>0)
return true;
else
return false;
}
}
2.27
//*********Found**********
import javax.swing.*;
public class Java_2{
public static void main( String args[] ){
int frequency1 = 0, frequency2 = 0,
frequency3 = 0, frequency4 = 0,
frequency5 = 0, frequency6 = 0, face;
//骰子旋转500次的代码
for ( int roll = 1; roll <= 500; roll++ ) {
face = 1 + (int) ( Math.random() * 6 );
//*********Found**********
switch ( face) {
case 1:
++frequency1;
break;
case 2:
++frequency2;
break;
case 3:
++frequency3;
break;
case 4:
++frequency4;
break;
case 5:
++frequency5;
break;
case 6:
++frequency6;
break;
}
}
//*********Found**********
JTextArea outputArea = new JTextArea( 7, 10 );
outputArea.setText(
"面\t频率" +
"\n1\t" + frequency1 +
"\n2\t" + frequency2 +
"\n3\t" + frequency3 +
"\n4\t" + frequency4 +
"\n5\t" + frequency5 +
"\n6\t" + frequency6 );
//*********Found**********
JOptionPane.showMessageDialog( null, outputArea,
"骰子旋转500次",
JOptionPane.INFORMATION_MESSAGE );
//*********Found**********
System.exit( 0 );
}
}
2.28
import java.io.*;
import java.util.Vector;
public class Java_2{
public static void main(String s[]){
Vector v=new Vector();
try{
//*********Found**********
BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); //键盘输入
String str = "";
System.out.println("请输入用户和密码信息，中间用空格隔开，输入quit退出:");
while (!(str.equals("quit")||str.equals("QUIT"))){
str = in.readLine();
//*********Found**********
if(isValid(str)) //验证输入是否有空格
v.add(str);
else{
if(!(str.equals("quit")||str.equals("QUIT")))
System.out.println("The string is NOT valid!");
}
}
System.out.println("请输入保存到的文件名:");
//*********Found**********
str=in.readLine();
String curDir = System.getProperty("user.dir");
File savedfile=new File(curDir+"\\"+str);
//*********Found**********
BufferedWriter out = new BufferedWriter(new FileWriter(savedfile));
for(int i=0; i<v.size(); i++){
String tmp=(String)v.elementAt(i);
out.write(tmp);
//*********Found**********
out.write("\n "); //换行
}
out.close();
}
//*********Found**********
catch(Exception e){
System.out.print("ERROR:"+e.getMessage());
}
}
/**
* 判定输入的字符串是否符合规范
* @param s 输入的待校验的字符串
* @return 校验的结果，正确则返回为真
*/
public static boolean isValid(String s){
if(s.indexOf(" ")>0) return true;
else return false;
}
}
2.29
import javax.swing.*;
import java.awt.event.*;
public class Java_2 extends JFrame {
private JButton b;
public Java_2(String s){
setTitle(s);
b=new JButton("Hello");
getContentPane().add(b);
//*********Found********
b.addActionListener( new HandleButton() );
setSize(150,150);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//*********Found********
setVisible(true);
}
class HandleButton implements ActionListener{
public void actionPerformed(ActionEvent e){
//*********Found********
if ( "Hello".equals(b.getText()) )
b.setText("你好");
else
b.setText("Hello");
}
}
public static void main(String args[]){
//*********Found********
new Java_2("二级Java");
}
}
2.30
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Java_2{
public static void main(String[] args){
RadioButtonFrame frame = new RadioButtonFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//*********Found**********
frame.show();
}
}
class RadioButtonFrame extends JFrame{
public RadioButtonFrame(){
setTitle("Radio按钮实例");
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
Container contentPane = getContentPane();
label = new JLabel("热烈庆祝Java程序语言开考三周年");
label.setForeground(Color.yellow);
contentPane.setBackground(Color.red);
label.setFont(new Font("黑体", Font.PLAIN, DEFAULT_SIZE));
contentPane.add(label, BorderLayout.CENTER);
buttonPanel = new JPanel();
group = new ButtonGroup();
addRadioButton("小", 8);
addRadioButton("中", 12);
addRadioButton("大", 18);
addRadioButton("特大", 30);
contentPane.add(buttonPanel, BorderLayout.SOUTH);
}
public void addRadioButton(String name, final int size){
boolean selected = size == DEFAULT_SIZE;
//*********Found**********
JRadioButton button = new JRadioButton(name, selected);
group.add(button);
buttonPanel.add(button);
ActionListener listener = new ActionListener(){
//*********Found**********
public void actionPerformed(ActionEvent evt){
label.setFont(new Font("黑体", Font.PLAIN, size));
}
};
//*********Found**********
button.addActionListener(listener);
}
public static final int DEFAULT_WIDTH = 340;
public static final int DEFAULT_HEIGHT = 200;
private JPanel buttonPanel;
private ButtonGroup group;
private JLabel label;
private static final int DEFAULT_SIZE = 12;
}
2.31
import javax.swing.*;
import java.awt.*;
public class Java_2{
public static void main(String[] args){
WelcomFrame frame = new WelcomFrame();
//*********Found**********
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE );
frame.setVisible(true);
}
}
//*********Found**********
class WelcomFrame extends JFrame{
public WelcomFrame(){
setTitle("Java等级考试");
//*********Found**********
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
WelcomPanel panel = new WelcomPanel();
Container contentPane = getContentPane();
contentPane.add(panel);
}
public static final int DEFAULT_WIDTH = 250;
public static final int DEFAULT_HEIGHT = 100;
}
//*********Found**********
class WelcomPanel extends JPanel{
public void paintComponent(Graphics g){
super.paintComponent(g);
g.drawString("欢迎参加Java等级考试！",MESSAGE_X, MESSAGE_Y);
}
public static final int MESSAGE_X = 60;
public static final int MESSAGE_Y = 50;
}
2.32
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import javax.swing.Timer;
public class Java_2{
public static void main(String[] args){
//*********Found**********
ActionListener listener = new TimePrinter();
Timer t = new Timer(10000, listener);
t.start();
JOptionPane.showMessageDialog(null, "退出程序吗?");
System.exit(0);
}
}
//*********Found**********
class TimePrinter implements ActionListener{
//*********Found**********
public void actionPerformed(ActionEvent event){
Date now = new Date();
System.out.println("At the tone, the time is " + now);
Toolkit.getDefaultToolkit().beep();
}
}
2.33
//*********Found**********
import javax.swing.*;
public class Java_2{
public static void main(String[] args){
//*********Found**********
String input = JOptionPane.showInputDialog("你想抽几个数?");
int k = Integer.parseInt(input);
input = JOptionPane.showInputDialog("你想在自然数中抽的最大数是几?");
int n = Integer.parseInt(input);
int lotteryOdds = 1;
//*********Found**********
for (int i = 1; i <= k; i++)
lotteryOdds = lotteryOdds * (n - i + 1)/i;
//*********Found**********
System.out.println("你中奖的几率是1/" + lotteryOdds + ". Good luck!");
System.exit(0);
}
}
2.34
import java.util.Random;
public class Java_2{
//*********Found**********
public static void main(String args[]){
Random random = new Random();
//*********Found**********
float x = random.nextFloat();//产生0.0与1.0之间的一个浮点数
//*********Found**********
int n = Math.round(21*x); //构造20以内的一个整数
long f = 1 ; //保存阶乘的结果
int k = 1 ; //循环变量
do {
//*********Found**********
f*= k++;
}while(k<=n);
System.out.println(n+"!= "+f);
}
}
2.35
import java.awt.*;
import java.awt.geom.*;
//*********Found**********
import javax.swing.*;
public class Java_2
{
public static void main(String[] args)
{
DrawFrame frame = new DrawFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//*********Found**********
frame.setVisible(true);
}
}
//*********Found**********
class DrawFrame extends JFrame
{
public DrawFrame()
{
setTitle("千里共婵娟");
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
DrawPanel panel = new DrawPanel();
//*********Found**********
Container contentPane = getContentPane();
//*********Found**********
contentPane.add(panel);
}
public static final int DEFAULT_WIDTH = 400;
public static final int DEFAULT_HEIGHT = 240;
}
//*********Found**********
class DrawPanel extends JPanel
{
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
double l = 0;
double r = 0;
double w = 400;
double h = 400;
Rectangle2D re = new Rectangle2D.Double(l,r,w,h);
g2.setPaint(Color.BLUE);
g2.fill(re);
double leftX = 50;
double topY = 50;
double width = 50;
double height = 50;
Rectangle2D rect = new Rectangle2D.Double(leftX, topY, width, height);
Ellipse2D ellipse = new Ellipse2D.Double();
ellipse.setFrame(rect);
g2.setPaint(Color.YELLOW);
g2.fill(ellipse);
}
}
2.36(*)
import java.awt.*;
import javax.swing.*;
public class Java_2{
int grades[][] = { { 77, 68, 86, 73 },
{ 96, 87, 89, 81 },
{ 70, 90, 86, 81 } };
int students, exams;
String output;
JTextArea outputArea;
public Java_2(){
students = grades.length;
exams = grades[ 0 ].length;
JFrame f = new JFrame();
f.setSize(300,300);
f.setVisible(true);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//*********Found**********
outputArea = new JTextArea();
Container c = f.getContentPane();
//*********Found**********
c.add(outputArea);
output = "数组是:";
buildString();
output += "\n\n最高分: " + maximum() + "\n";
//*********Found**********
for ( int i = 0; i < students; i++ )
output += "\n第" + (i+1) + "个学生的平均分是: " +
average( grades[ i ] );
//*********Found**********
outputArea.setText( output );
}
//找最高分
public int maximum(){
int highGrade = 0;
for ( int i = 0; i < students; i++ )
for ( int j = 0; j < exams; j++ )
if ( grades[ i ][ j ] > highGrade )
//*********Found**********
highGrade = grades[i][j];
return highGrade;
}
//对各组学生确定平均分
public int average( int setOfGrades[] ){
int total = 0;
for ( int i = 0; i < setOfGrades.length; i++ )
//*********Found**********
total += setOfGrades[i];
return total /exams;
}
//输出格式
public void buildString(){
output += " ";
for ( int i = 0; i < exams; i++ )
output += "[" + i + "] ";
for ( int i = 0; i < students; i++ ) {
output += "\ngrades[" + i + "] ";
for ( int j = 0; j < exams; j++ )
output += grades[ i ][ j ] + " ";
}
}
public static void main(String[ ]args){
new Java_2();
}
}
2.37
class Point{
public int x,y;
public Point() {
}
public Point(int x,int y){
this.x = x;
this.y = y;
}
//*********Found**********
public Point(Point p){
x = p.x;
y = p.y;
}
public int getX(){
return x;
}
public int getY(){
return y;
}
public void moveTo(int x,int y){
this.x = x;
this.y = y;
}
public void moveTo(Point p){
x = p.x;
y = p.y;
}
public String toString(){
return "("+ x + ","+ y + ")";
}
public void translate(int dx,int dy){ //平移
this.x += dx;
//*********Found**********
this.y + = dy;
}
}
public class Java_2 {
public static void main(String args[]){
//*********Found**********
Point p = new Point(5,5);
System.out.println("点的当前坐标：("+p.x + "," + p.y+")");
p.translate(3,4);
//*********Found**********
System.out.println("平移到："+p.toString());
}
}
2.38
import javax.swing.*;
import java.awt.event.*;
import java.io.*;
import java.awt.*;
public class Java_2 implements ActionListener {
private JFrame frame;
private JButton button,saveButton;
private JTextArea textArea;
private JFileChooser dia;
private JPanel buttonPanel;
public void init() {
frame=new JFrame("file chooser");
dia=new JFileChooser();
button=new JButton("open file");
button.setActionCommand("open");
//*********Found**********
button.addActionListener(this);
saveButton=new JButton("save file");
//*********Found**********
saveButton.addActionListener(this);
buttonPanel=new JPanel();
buttonPanel.add(button);
buttonPanel.add(saveButton);
//*********Found**********
textArea= new JTextArea("",10,10);
//*********Found**********
frame.getContentPane().add(buttonPanel,BorderLayout.NORTH);
frame.getContentPane().add(textArea,BorderLayout.CENTER);
frame.setSize(300,300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
//*********Found**********
public void actionPerformed(ActionEvent event) {
if(event.getActionCommand().equals("open"))
dia.showOpenDialog(frame);
else
dia.showSaveDialog( frame );
dia.setVisible(true);
File file=dia.getSelectedFile();
if (file!=null){
String fileName=file.getAbsolutePath();
textArea.append("path of selected file: "+fileName+"\r\n");
}
}
public static void main(String args[]){
Java_2 example=new Java_2();
//*********Found**********
example.init();
}
}
2.39
import javax.swing.*;
public class Java_2{
public static void main( String args[] ){
StringBuffer buf = new StringBuffer( "你好!祝你成功!" );
String output = "buf = " + buf.toString() +
"\nCharacter at 0: " + buf.charAt( 0 ) +
"\nCharacter at 4: " + buf.charAt( 4 );
//*********Found**********
char charArray[] = new char[ buf.length() ];
//*********Found**********
buf.getChars( 0, buf.length(), charArray, 0 );
output += "\n\n在字符串缓存中的字符是: ";
//*********Found**********
for ( int i = 0; i < charArray.length; ++i )
output += charArray[ i ];
buf.setCharAt( 0, '您' );
buf.setCharAt( 6, '材' );
//*********Found**********
output += "\n\nbuf = " + buf.toString();
buf.reverse( );
output += "\n\nbuf = " + buf.toString();
JOptionPane.showMessageDialog( null, output,
"字符串缓存的字符相关方法示范",
JOptionPane.INFORMATION_MESSAGE );
System.exit( 0 );
}
}
2.40
public class Java_2 {
public static void main(String[] args) {
Person p = new Person("Zhao",20);
Student s = new Student("Wang",18,"Cambridge");
System.out.println(p);
System.out.println(s);
}
}
class Person {
private String name;
private int age;
public Person(String name, int age) {
//*********Found********
this.name= name;
//*********Found********
this.age = age;
}
public void setName(String n) {
//*********Found********
name= n;
}
public String toString() {
return "Name: " + name + " Age: " + age;
}
}
class Student extends Person {
private String school;
public Student(String name, int age, String s) {
//*********Found********
super(name,age);
school = s;
}
public String toString() {
//*********Found********
return super.toString() + " School: " + school;
}
}
2.41
import java.io.*;
import java.lang.Thread;
//**************found*****************
class MyThread extends Thread{
public int x = 0;
public void run(){
//**************found*****************
System.out.println(++x);
}
}
//**************found*****************
class R implements Runnable{
private int x = 0;
//**************found*****************
public void run(){
System.out.println(++x);
}
}
public class Java_2 {
public static void main(String[] args) throws Exception{
for(int i=0;i<5;i++){
Thread t = new MyThread();
t.start();
}
Thread.sleep(1000);
R r = new R();
//**************found*****************
for(int i=0;i<5 ;i++){
Thread t = new Thread(r);
//**************found*****************
t.start();
}
}
}
2.42
//***************************Found*********************
class PrintStrings implements Runnable{
int ind = 0 ;
//***************************Found*********************
String[] strings = { "one", "two", "three", "four", "five"};
public PrintStrings( int n) {
if( n < 0)
n = 0;
else if ( n >= strings.length)
//***************************Found*********************
n = strings.length-1 ;
ind = n;
}
//***************************Found*********************
public void run( ){
while(ind < strings.length){
System.out.print(strings[ind] + " ");
//***************************Found*********************
ind++;
}
System.out.println();
}
}
public class Java_2{
public static void main(String[] args){
PrintStrings p = new PrintStrings(-1);
//***************************Found*********************
Thread t = new Thread(p);
t.start( );
}
}
2.43(*)
//**********found**********
public class Java_2 extends Thread {
public static void main(String[ ] args) throws Exception{
int i=0;
//**********found**********
Thread t = new Java_2( );
//**********found**********
t.start();
while( true){
System.out.println("Good Morning"+ i++);
if (i == 2 && t.isAlive()){
System.out.println("Main waiting for Hello!");
//**********found**********
t.join(); //等待线程t运行结束
}
//**********found**********
if (i==5) break;
}
}
//**********found**********
public void run(){
int i =0;
while( true){
System.out.println("Hello"+ i++);
if (i==5) break ;
}
}
}
2.44
import java.io.*;
public class Java_2 {
public static void main(String[] args) {
try {
//**********found**********
FileInputStream in = new FileInputStream("in.txt");
FileOutputStream out = new FileOutputStream("out.txt");
BufferedInputStream bufferedIn = new BufferedInputStream(in);
//**********found**********
BufferedOutputStream bufferedOut = new BufferedOutputStream(out);
//**********found**********
byte[] data = new byte[1];
//**********found**********
while(bufferedIn.read(data) != -1) {
bufferedOut.write(data);
}
bufferedOut.flush();
bufferedIn.close();
//**********found**********
bufferedOut.close();
//**********found**********
} catch(ArrayIndexOutOfBoundsException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
2.45
import java.lang.*;
abstract class Figure {
//**********Found**********
public abstract double area();
}
class Circle extends Figure{
double r;
Circle(double r){
this.r=r;
}
public double area(){
//**********Found**********
return Math.PI*r*r;
}
}
class Rectangle extends Figure{
double a,b;
Rectangle(double a,double b) {
this.a=a;
this.b=b;
}
public double area() {
//**********Found**********
return a*b;
}
}
public class Java_2 {
public static void main(String[] args){
Figure[] fig=new Figure[3];
fig[0]=new Circle(1.0);
fig[1]=new Circle(2.0);
//**********Found**********
fig[2]=new Rectangle(2.0,3.0) ;
for(int i=0;i<3;i++)
//**********Found**********
System.out.println("The area of figure "+i+" is:"+ fig[i].area() );
}
}
2.46
//**********Found**********
class Account {
private float balance = 1000;
public float getBalance() {
return balance;
}
public void setBalance(float balance) {
this.balance = balance;
}
public synchronized void withdrawals(float money) {
if (balance >= money) {
System.out.println("被取走" + money + "元!");
try{
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
//**********Found**********
balance -= money;
} else {
System.out.println("对不起,余额不足!");
}
}
}
//**********Found**********
class TestAccount1 extends Thread {
private Account account;
public TestAccount1(Account account) {
this.account = account;
}
//**********Found**********
public void run() {
account.withdrawals(600);
System.out.println("余额为:" + account.getBalance() + "元!");
}
}
//**********Found**********
class TestAccount2 extends Thread {
private Account account;
public TestAccount2(Account account) {
this.account = account;
}
public void run() {
account.withdrawals(500);
System.out.println("余额为:" + account.getBalance() + "元!");
}
}
public class Java_2 {
public static void main(String[] args) {
Account account = new Account();
TestAccount1 testAccount1 = new TestAccount1(account);
testAccount1.start();
//**********Found**********
TestAccount2 testAccount2 = new TestAccount2(account);
testAccount2.start();
}
}
2.47
import java.util.*;
//**********Found**********
class Java_2 extends Thread {
String name;
//**********Found**********
public Java_2( String n) {
name = n;
}
//**********Found**********
public static void main(String args[]) throws Exception {
int i = 0;
//**********Found**********
Java_2 t = new Java_2("date" );
t.start();
while( true){
//**********Found**********
System.out.println("in main: Hello! "+ t);
if (i == 2 && t.isAlive()){
System.out.println("Main waiting for date!");
t.join( );
}
//**********Found**********
if (i==5) break ;
}
}
public void run() {
int i;
for (i=0;i<3; i++){
System.out.println("in "+name+": "+new Date());
}
}
}
2.48(*)
class Mystack
{
int index=0;
private char[] data=new char [10];
//**********Found**********
public synchronized void push(char c){
while(index>=10) {
try {
this.wait();
}catch(InterruptedException e) {
e.printStackTrace();
}
}
this.notifyAll();
//**********Found**********
data[index] = c ;
index++;
}
public synchronized char pop(){
while(index<=0) {
try {
this.wait();
}catch(InterruptedException e) {
e.printStackTrace();
}
}
this.notifyAll();
//**********Found**********
index--;
return data[index];
}
}
class PushChar extends Thread
{
Mystack s;
char c;
PushChar(Mystack s){
this.s=s;
}
public void run(){
System.out.println ("start push");
for (int i=0; i<20; i++){
c=(char)(Math.random()*26+'A');
//**********Found**********
s.push(c);
System.out.println("A:push "+c);
}
}
}
class PopChar extends Thread
{
Mystack s;
char c;
PopChar(Mystack s){
//**********Found**********
this.s=s;
}
public void run(){
System.out.println ("start pop");
for(int j=0;j<20;j++) {
c=s.pop();
System.out.println("B:pop "+c);
}
}
}
public class Java_2 {
public static void main (String[] args)
{
//**********Found**********
Mystack s=new Mystack();
PushChar a=new PushChar(s);
PopChar b=new PopChar(s);
a.start();
b.start();
}
}
2.49
//**********Found**********
class Tree {
public void root(){
String sSite = "土壤中";
String sFunction = "吸收养份";
print("位置："+sSite);
print("功能："+sFunction);
}
//**********Found**********
public void bolo(){
String sSite = "地面";
String sFunction = "传递养份";
print("位置："+sSite);
print("功能："+sFunction);
}
public void branch(){
String sSite = "树干上";
String sFunction = "传递养份";
print("位置："+sSite);
print("功能："+sFunction);
}
public void leaf(){
String sSite = "树梢";
String sFunction = "光合作用";
String sColor = "绿色";
print("位置："+sSite);
print("功能："+sFunction);
print("颜色："+sColor);
}
//**********Found**********
public void print(Object oPara){
System.out.println(oPara);
}
}
//**********Found**********
class Java_2 extends Tree{
public void leaf(){
super.leaf();
String sShape = "长形";
super.print("形状："+sShape);
}
//**********Found**********
public void flower(){
print("哈哈，柳树没有花！！");
}
public static void main(String[] args){
//**********Found**********
Java_2 o = new Java_2();
o.print("柳树树根：");
o.root();
o.print("柳树树干：");
o.bolo();
o.print("柳树树枝：");
o.branch();
o.print("柳树树叶：");
o.leaf();
o.print("柳树花：");
o.flower();
}
}
2.50(*)
//**********Found**********
class MyException extends Exception {
private static final long serialVersionUID = 1L;
public MyException() {
}
public MyException(String msg) {
super(msg);
}
public MyException(String msg, int x) {
super(msg);
i = x;
}
//**********Found**********
public int val() {
return i;
}
//**********Found**********
private int i;
}
public class Java_2 {
//**********Found**********
public static void a() throws MyException {
System.out.println("Throwing MyException from a()");
throw new MyException();
}
public static void b() throws MyException {
System.out.println("Throwing MyException from b()");
throw new MyException("Originated in b()");
}
public static void c() throws MyException {
System.out.println("Throwing MyException from c()");
//**********Found**********
throw new MyException("Originated in c()", 47);
}
public static void main(String[] args) {
try {
a();
//**********Found**********
} catch (MyException e) {
e.getMessage();
}
try {
b();
} catch (MyException e) {
e.toString();
}
try {
c();
} catch (MyException e) {
e.printStackTrace();
System.out.println("error code: " + e.val());
}
}
}
2.51
import java.util.Scanner;
import java.io.*;
public class Java_2 {
int fourthPower(int n) {
return n*n*n*n;
}
int narcissiExt(int fromNum,int number[]) {
int i=0;
int m=fromNum;
int m1=m%10;
int m2=(m/10)%10;
int m3=(m/100)%10;
//**********Found**********
int m4 = m/1000;
for(m=fromNum;m<=9999;m++) {
int sum=fourthPower(m1)+fourthPower(m2)+fourthPower(m3)+fourthPower(m4);
//**********Found**********
if(m == sum ) {
number[i]=m;
//**********Found**********
++i;
}
m1=m1+1;
if(m1==10) {
m1=0;
m2=m2+1;
if(m2==10) {
//**********Found**********
m2 = 0;
m3=m3+1;
if(m3==10) {
m3=0;
m4=m4+1;
}
}
}
}
return i;
}
public static void main(String[] args) throws Exception{
Scanner input = new Scanner(System.in);
System.out.println("Input a number：");
int n = input.nextInt();
input.close();
int[] num= new int [10];
int counter=new Java_2().narcissiExt(n,num);
//**********Found**********
PrintWriter pw=new PrintWriter ("java_2.txt");
pw.print("There are "+counter+" extended Narcissistic numbers ");
pw.println(" >= "+n+". They are:");
for(int i=0;i<counter;i++) {
pw.println(num[i]);
}
//**********Found**********
pw.close();
}
}
2.52
public class Java_2 {
public static void main(String []args) {
Shape[] s = new Shape[3];
s[0] = new Circle(5.0);
s[1] = new Rectangle(3.0, 4.0);
s[2] = new Rectangle(5.0, 6.0);
//**********Found**********
System.out.println("Total Area = " + Poly.dostuff(s));
}
}
//**********Found**********
abstract class Shape {
abstract public double calcArea();
}
class Circle extends Shape {
private double radius;
public Circle(double radius) {
//**********Found**********
this.radius = radius;
}
//**********Found**********
public double calcArea() {
return radius * radius * 3.14;
}
}
class Rectangle extends Shape {
private double length, width;
public Rectangle(double a, double b) {
length = a;
width = b;
}
public double calcArea() {
//**********Found**********
return length*width ;
}
}
class Poly {
static double dostuff(Shape[] s) {
double total = 0;
for (int i = 0; i < s.length; i++) {
//**********Found**********
total +=s[i].calcArea();
}
return total;
}
}
2.53
import java.io.*;
public class Java_2{
String[] number = new String[5];
String[] name = new String[5];
int[][] grade = new int[5][3];
float[] sum = new float[5];
public static void main(String[] args) throws Exception{
Java_2 student = new Java_2();
student.input();
//**********Found**********
student.output();
}
void input( ) throws IOException{
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
try{
for(int i=0;i<5;i++){
System.out.println("请输入学生学号：");
number[i] = br.readLine();
//**********Found**********
System.out.println("请输入第"+(i+1)+"名学生姓名及三门课成绩：");
name[i] = br.readLine();
for(int j=0;j<3;j++){
grade[i][j] = Integer.parseInt( br.readLine() );
}
System.out.println();
sum[i] = grade[i][0] + grade[i][1] + grade[i][2];
}
}catch(NumberFormatException e){
System.out.println("输入数据有误！");
}
}
void output( )throws IOException{
//**********Found**********
FileWriter fw = new FileWriter("student.txt");
BufferedWriter bw = new BufferedWriter(fw);
bw.write("No. "+"name "+"grade 1 "+"grade 2 "+"grade 3 "+"average ");
bw.newLine();
for(int i=0;i<5;i++){
bw.write(number[i]);
//**********Found**********
bw.write(" "+ name[i]);
for(int j=0;j<3;j++)
bw.write(" "+grade[i][j]);
//**********Found**********
bw.write(" "+sum[i]/3);
bw.newLine();
}
//**********Found**********
bw.close();
}
}
2.54
public class Java_2 {
public static void main(String[] args){
Workshop shop;
shop = new Workshop();
Thread w1 = new Thread(shop);
Thread w2 = new Thread(shop);
w1.setName("Worker A");
w2.setName("Worker B");
w1.start();
w2.start();
}
}
//**********Found**********
class Workshop implements Runnable{
//**********Found**********
private int products = 0;
//**********Found**********
public void run( ){
for (int i = 0; i<10; i++){
produce();
//**********Found**********
try{
Thread.sleep(2);
//**********Found**********
}catch(Exception e){ }
}
}
public void produce(){
//**********Found**********
synchronized(this){
if(products <10){
products++;
System.out.print(Thread.currentThread().getName());
System.out.println( " adds one product, and totally " + products +" products produced.");
}
}
}
}
2.55
import java.awt.*;
import java.awt.event.*;
//*********Found********
import javax.swing.*;
public class Java_2 extends JFrame implements WindowListener {
//*********Found********
public Java_2() {
//*********Found********
setLayout(new FlowLayout());
add(new JButton("Button 1"));
add(new JButton("2"));
add(new JButton("Button 3"));
//*********Found********
addWindowListener(this);
}
public static void main(String args[]) {
Java_2 window = new Java_2();
window.setTitle("Swing Test");
window.pack();
//*********Found********
window.setVisible(true);
}
public void windowClosing(WindowEvent e) {
System.exit(0);
}
public void windowClosed(WindowEvent e) { }
public void windowOpened(WindowEvent e) { }
public void windowIconified(WindowEvent e) { }
public void windowDeiconified(WindowEvent e) { }
public void windowActivated(WindowEvent e) { }
public void windowDeactivated(WindowEvent e) { }
}
2.56
public class Java_2{
public static void main(String[] args){
Manager m = new Manager("Tom",2000,"Finance");
Worker w = new Worker("James",1500);
//**********Found**********
System.out.println(m.getDetails());
//**********Found**********
System.out.println(w.getDetails());
}
}
class Employee {
private String name ;
private int salary;
//**********Found**********
public Employee(String name,int salary){
this.name = name;
this.salary = salary;
}
public String getDetails( ){
return "Name: "+name+", Salary: "+salary;
}
}
class Worker extends Employee{
public Worker(String name,int salary){
//**********Found**********
super(name,salary);
}
}
class Manager extends Employee {
private String department ;
public Manager(String name,int salary,String department){
//**********Found**********
super(name,salary);
this.department = department;
}
public String getDetails( ){
//**********Found**********
return super.getDetails() + ", Department: " + department;
}
}
2.57
//**********Found**********
import java.io.*;
public class Java_2 {
public static void main(String[] args) {
File f = new File("input.txt");
//**********Found**********
File outFile=new File("output.txt");
InputStreamReader isr = null;
//**********Found**********
OutputStreamWriter osw = null;
try {
isr = new InputStreamReader (new FileInputStream(f));
osw = new OutputStreamWriter(new FileOutputStream(outFile));
//**********Found**********
} catch (FileNotFoundException e) {
e.printStackTrace();
}
BufferedReader reader=new BufferedReader(isr);
String rin;
try {
//**********Found**********
while ((rin = reader.readLine()) != null) {
System.out.println(rin);
//**********Found**********
osw.write(rin +"\r\n");
}
osw.flush();
} catch (IOException e) {
e.printStackTrace();
}
}
}
3.综合应用
3.1
import java.text.DecimalFormat;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
//*********Found********
public class Java_3 extends JFrame implements ActionListener {
private JTextField input1, input2, output;
private int number1, number2;
private double result;
// 初始化
public Java_3()
{
//*********Found********
super( "示范异常" );
Container c = getContentPane();
c.setLayout( new GridLayout( 3, 2 ) );
c.add( new JLabel( "输入分子",
SwingConstants.RIGHT ) );
input1 = new JTextField( 10 );
c.add( input1 );
c.add(
new JLabel( "输入分母和回车",
SwingConstants.RIGHT ) );
input2 = new JTextField( 10 );
c.add( input2 );
input2.addActionListener( this );
c.add( new JLabel( "计算结果", SwingConstants.RIGHT ) );
output = new JTextField();
c.add( output );
setSize( 425, 100 );
show();
}
//处理 GUI 事件
public void actionPerformed( ActionEvent e )
{
DecimalFormat precision3 = new DecimalFormat( "0.000" );
output.setText( "" ); // 空的JTextField输出
//*********Found********
try{
number1 = Integer.parseInt( input1.getText() );
number2 = Integer.parseInt( input2.getText() );
result = quotient( number1, number2 );
//*********Found********
output.setText(precision3.format(result));
}
catch ( NumberFormatException nfe ) {
JOptionPane.showMessageDialog( this,
"你必须输入两个整数",
"非法数字格式",
JOptionPane.ERROR_MESSAGE );
}
catch ( Exception dbze ) {
//*********Found********
JOptionPane.showMessageDialog( this,
"除法异常",
"除数为零",
JOptionPane.ERROR_MESSAGE );
}
}
// 定义求商的方法，如遇除数为零时，能抛出异常。
public double quotient( int numerator, int denominator )
throws Exception
{
if ( denominator == 0 )
throw new Exception();
return ( double ) numerator / denominator;
}
public static void main( String args[] )
{
Java_3 app = new Java_3();
app.addWindowListener(
new WindowAdapter() {
public void windowClosing( WindowEvent e )
{
e.getWindow().dispose();
System.exit( 0 );
}
}
);
}
}
/* JOptionPane类的常用静态方法如下：
showInputDialog()
showConfirmDialog()
showMessageDialog()
showOptionDialog()
*/
3.2
import java.awt.*;
import java.awt.font.*;
import java.awt.geom.*;
import javax.swing.*;
public class Java_3
{
public static void main(String[] args)
{
FontFrame frame = new FontFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
//*********Found********
class FontFrame extends JFrame
{
public FontFrame()
{
setTitle("沁园春.雪");
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
FontPanel panel = new FontPanel();
Container contentPane = getContentPane();
//*********Found********
contentPane.add(panel);
}
public static final int DEFAULT_WIDTH = 300;
public static final int DEFAULT_HEIGHT = 200;
}
//*********Found********
class FontPanel extends JPanel
{
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
String message = "数风流人物，还看今朝！";
Font f = new Font("隶书", Font.BOLD, 24);
g2.setFont(f);
FontRenderContext context = g2.getFontRenderContext();
Rectangle2D bounds = f.getStringBounds(message, context);
double x = (getWidth() - bounds.getWidth()) / 2;
double y = (getHeight() - bounds.getHeight()) / 2;
double ascent = -bounds.getY();
double baseY = y + ascent;
g2.setPaint(Color.RED);
//*********Found********
g2.drawString(message, (int)x, (int)(baseY));
}
}
3.3
public class Java_3{
public static void main(String[] args) {
String text = "Beijing, the Capital City, is the political,"
+ "cultural and diplomatic centre of China. It has"
+ "become a modern international cosmopolitan city"
+ "with more than 11 million people. The Capital"
+ "International Airport, 23.5 km from the city centre,"
+ "is China's largest and most advanced airport.";
int vowels = 0 ;
//*********Found*********
int textLength= text.length();
for(int i = 0; i < textLength; i++) {
//*********Found*********
char ch = Character.toLowerCase(text.charAt(i));
if(ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u') {
//*********Found*********
vowels++;
}
}
System.out.println("The text contained vowels: " + vowels + "\n" );
}
}
3.4
import java.awt.*;
import javax.swing.*;
public class Java_3{
public static void main(String[] args){
BeijingFrame frame = new BeijingFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.show();
}
}
//*********Found*********
class BeijingFrame extends JFrame{
public BeijingFrame(){
setTitle("Welcome to Beijing");
Container contentPane = getContentPane();
BeijingPanel panel = new BeijingPanel();
contentPane.add(panel);
pack();
}
}
class BeijingPanel extends JPanel{
public BeijingPanel(){
//*********Found*********
setLayout(new BorderLayout() );
ImageIcon icon = new ImageIcon("tiantan.jpg");
//*********Found*********
jLC = new JLabel( icon );
add(jLC, BorderLayout.CENTER);
lpanel = new JPanel();
jLS = new JLabel("The Temple of Heaven");
lpanel.add(jLS);
add(lpanel, BorderLayout.SOUTH);
}
private JLabel jLC;
private JLabel jLS;
private JPanel panel;
private JPanel lpanel;
}
3.5
//*********Found**********
import javax.swing.JFrame;
import java.awt.*;
public class Java_3{
static final int WIDTH=300;
static final int HEIGHT=200;
public static void main(String[] args){
//*********Found**********
JFrame jf=new JFrame();
jf.setSize(WIDTH,HEIGHT);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//*********Found**********
jf.setTitle("股票分析系统");
Toolkit kit=Toolkit.getDefaultToolkit();
Dimension screenSize=kit.getScreenSize();
int width=screenSize.width;
int height=screenSize.height;
int x=(width-WIDTH)/2;
int y=(height-HEIGHT)/2;
jf.setLocation (x,y);
//*********Found**********
jf.setVisible(true);
}
}
3.6（*）
import java.io.*;
public class Java_3{
public static int data[]={32,18,41,23,2,56,36,67,59,20};
public static void main(String args[]){
int i;
//*********Found**********
int index=data.length;
System.out.println("排序前:");
for(i=0;i<index;i++)
System.out.print(" "+data[i]+" ");
System.out.println();
//*********Found**********
BubbleSort( index );
System.out.println("排序后:");
for(i=0;i<index;i++)
System.out.print(" "+data[i]+" ");
System.out.println();
}
// 冒泡法排序
public static void BubbleSort(int index){
int i,j;
int temp;
for(j=1;j<index;j++){
for(i=index-1;i>=j;i--){
if(data[i]<data[i-1]){ //比较相邻的两个数
temp=data[i];
data[i]=data[i-1];
//*********Found**********
data[i-1]= temp ;
}
}
}
}
}
3.7
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Java_3{
public static void main(String[] args){
MulticastFrame frame = new MulticastFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.show();
}
}
class MulticastFrame extends JFrame{
public MulticastFrame(){
setTitle("MulticastTest");
setSize(WIDTH, HEIGHT);
MulticastPanel panel = new MulticastPanel();
Container contentPane = getContentPane();
//*********Found**********
contentPane.add(panel);
}
public static final int WIDTH = 300;
public static final int HEIGHT = 200;
}
class MulticastPanel extends JPanel{
public MulticastPanel(){
JButton newButton = new JButton("New");
add(newButton);
ActionListener newListener = new ActionListener(){
public void actionPerformed(ActionEvent event){
makeNewFrame();
}
};
newButton.addActionListener(newListener);
closeAllButton = new JButton("Close all");
add(closeAllButton);
}
private void makeNewFrame(){
final BlankFrame frame = new BlankFrame();
frame.show();
ActionListener closeAllListener = new ActionListener(){
public void actionPerformed(ActionEvent event){
//*********Found**********
frame.dispose(); //使窗口隐藏或消除
}
};
//*********Found**********
closeAllButton.addActionListener(closeAllListener);
}
private JButton closeAllButton;
}
class BlankFrame extends JFrame{
public BlankFrame(){
//*********Found**********
counter++ ;
setTitle("Frame " + counter);
setSize(WIDTH, HEIGHT);
setLocation(SPACING * counter, SPACING * counter);
}
public static final int WIDTH = 200;
public static final int HEIGHT = 150;
public static final int SPACING = 30;
private static int counter = 0;
}
3.8
import javax.swing.*;
import java.awt.event.*;
import java.io.*;
import java.awt.*;
//*********Found**********
public class Java_3 implements ActionListener{
JFrame f;
JTextArea ta;
JFileChooser fc;
Container c;
File myFile;
public static void main(String args[]){
Java_3 demo=new Java_3();
demo.go();
}
void go(){
JFrame f=new JFrame("File Chooser Demo");
JButton b=new JButton("Open file");
ta=new JTextArea("Where is your file path?",10,30);
//*********Found**********
b.addActionListener(this);
c=f.getContentPane();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.getContentPane().add("South",b);
f.getContentPane().add("Center",ta);
f.setSize(300,300);
f.setVisible(true);
}
public void actionPerformed(ActionEvent e){
fc=new JFileChooser();
//*********Found**********
int selected=fc.showOpenDialog(c);
if (selected==JFileChooser.APPROVE_OPTION){
myFile=fc.getSelectedFile();
//*********Found**********
ta.setText("You have selected file: "+myFile.getName());
}
}
}
3.9
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
//*********Found**********
public class Java_3 extends WindowAdapter implements ActionListener
{
private JFrame frame;
private JTextField name;
private JPasswordField pass;
private JLabel nameLabel;
private JLabel passLabel;
private JPanel textPanel;
private JPanel labelPanel;
private JButton button;
private JTextArea textArea;
public void initGUI()
{
frame=new JFrame("Frame with Dialog");
frame.addWindowListener(this);
button=new JButton("JDialog");
//*********Found**********
button.addActionListener(this);
textArea=new JTextArea("",3,10);
frame.getContentPane().add(textArea,BorderLayout.CENTER);
frame.getContentPane().add(button,BorderLayout.NORTH);
frame.setSize(400,300);
frame.setVisible(true);
}
public void actionPerformed(ActionEvent e)
{
final JDialog dia=new JDialog(frame,"login information");
JButton ok=new JButton("ok");
ok.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
textArea.setText("");
textArea.append("name:"+name.getText()+"\r\n");
textArea.append("passWord:"+new String(pass.getPassword())+"\r\n");
//*********Found**********
dia.setVisible(false); //隐藏对话框
}
});
name=new JTextField("",10);
pass=new JPasswordField("",10);
pass.setEchoChar('*');
textPanel=new JPanel();
textPanel.setLayout(new GridLayout(2,1,10,10));
textPanel.add(name);
textPanel.add(pass);
nameLabel=new JLabel("name");
passLabel=new JLabel("passWord");
labelPanel=new JPanel();
labelPanel.setLayout(new GridLayout(2,1,20,20));
labelPanel.add(nameLabel);
labelPanel.add(passLabel);
dia.getContentPane().add(labelPanel,BorderLayout.WEST);
dia.getContentPane().add(textPanel,BorderLayout.CENTER);
dia.getContentPane().add(ok,BorderLayout.SOUTH);
dia.setSize(200,130);
dia.setVisible(true);
}
public void windowClosing(WindowEvent event)
{
frame.setVisible(false);
System.exit(0);
}
public static void main(String args[])
{
Java_3 example=new Java_3();
//*********Found**********
example.initGUI();
}
}
3.10
import java.awt.*;
import java.awt.event.*;
//*********Found**********
import javax.swing.*;
public class Java_3 {
public static void main(String[ ] args) {
JFrame frame = new JFrame("Demo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//*********Found**********
frame.getContentPane().add(new Change());
frame.pack();
frame.setVisible(true);
}
}
class Change extends JPanel {
int count = 200;
JLabel l1;
JButton b1, b2;
public Change( ) {
setPreferredSize(new Dimension(280, 60));
l1 = new JLabel("200");
b1 = new JButton("增大");
b2 = new JButton("减小");
add(l1);
//*********Found**********
add(b1);
//*********Found**********
add(b2);
b1.addActionListener( new BListener( ) );
b2.addActionListener( new BListener( ) );
}
//*********Found**********
private class BListener implements ActionListener {
//*********Found**********
public void actionPerformed(ActionEvent e) {
if (e.getSource( ) == b1) {
count++;
} else {
count--;
}
l1.setText("" + count);
}
}
}
3.11
import java.awt.*;
import java.awt.event.*;
//*********Found**********
import javax.swing.*;
//*********Found**********
public class Java_3 extends JPanel{
private int counter = 0;
private JButton closeAllButton;
public Java_3() {
JButton newButton = new JButton("New");
//*********Found**********
add(newButton);
newButton.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent evt){
CloseFrame f = new CloseFrame();
counter++;
f.setTitle("窗体 " + counter);
f.setSize(200, 150);
f.setLocation(30 * counter, 30 * counter);
//*********Found**********
f.setVisible(true);
closeAllButton.addActionListener(f);
}
});
closeAllButton = new JButton("Close all");
add(closeAllButton);
}
public static void main(String[ ] args) {
JFrame frame = new JFrame();
frame.setTitle("多窗体测试");
frame.setSize(300, 200);
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
Container contentPane = frame.getContentPane();
contentPane.add(new Java_3());
frame.setVisible(true) ;
}
}
//*********Found**********
class CloseFrame extends JFrame implements ActionListener {
public void actionPerformed(ActionEvent evt) {
setVisible(false);
}
}
3.12
import java.io.*;
import java.awt.event.* ;
import javax.swing.*;
public class Java_3 implements ActionListener{
public static void main(String args[]){
Java_3 t = new Java_3();
//*********Found**********
JFrame f = new JFrame("Test");
JButton b = new JButton("复制文件");
b.setSize(100,40);
b.addActionListener(t);
f.setSize(400,400);
//*********Found**********
f.getContentPane().add(b);
f.pack();
f.setVisible(true) ;
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void actionPerformed(ActionEvent event){
try{
//*********Found**********
FileInputStream in=new FileInputStream("a.txt");
//*********Found**********
FileOutputStream out=new FileOutputStream("b.txt");
int c;
while ((c = in.read()) != -1)
out.write(c);
in.close();
out.close();
} catch( Exception e){
}
}
}
3.13
//*********Found**********
import javax.swing.*;
import java.awt.event.*;
import java.io.*;
import java.awt.*;
//*********Found**********
public class Java_3 implements ActionListener {
JFrame f;
JPanel p;
JColorChooser cc;
Container c;
Color myColor;
JMenuBar mb;
JMenu m1;
JMenuItem mi1;
public static void main(String args[]) {
Java_3 demo = new Java_3();
demo.go();
}
void go() {
JFrame f = new JFrame("File Chooser Demo");
mb = new JMenuBar();
f.setJMenuBar(mb);
m1 = new JMenu("Edit");
mb.add(m1);
mi1 = new JMenuItem("Choose Color");
m1.add(mi1);
mi1.addActionListener(this);
//*********Found**********
c =f .getContentPane();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
p = new JPanel();
myColor = Color.red;
p.setBackground(myColor);
c.add("Center", p);
f.setSize(300, 300);
//*********Found**********
f.setVisible(true);
}
public void actionPerformed(ActionEvent e) {
//*********Found**********
cc = new JColorChooser();
myColor = cc.showDialog(c, "Choose window background color", Color.white);
p.setBackground(myColor);
}
}
3.14
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Java_3 {
public static void main(String[ ] args) {
JFrame frame = new JFrame("Demo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//*********Found**********
frame.getContentPane().add(new Change());
frame.pack();
//*********Found**********
frame.setVisible(true);
}
}
class Change extends JPanel{
int count = 200;
JLabel l1;
JButton b1, b2;
public Change() {
setPreferredSize(new Dimension(280, 60));
l1 = new JLabel("200");
b1 = new JButton("增大");
b2 = new JButton("减小");
add(l1);
add(b1);
add(b2);
b1.addActionListener(new BListener1());
//*********Found**********
b2.addActionListener(new BListener2());
}
private class BListener1 implements ActionListener {
public void actionPerformed(ActionEvent e) {
count++;
l1.setText("" + count);
}
}
private class BListener2 implements ActionListener {
public void actionPerformed(ActionEvent e) {
//*********Found**********
count --;
l1.setText("" + count);
}
}
}
3.15
import javax.swing.*;
import java.awt.event.*;
import java.io.*;
import java.awt.*;
//*********Found**********
public class Java_3 implements ActionListener{
JFrame f;
JPanel p;
JColorChooser cc;
Container c;
Color myColor;
JMenuBar mb;
JMenu m1;
JMenuItem mi1;
public static void main(String args[]){
Java_3 demo=new Java_3();
demo.go();
}
void go(){
JFrame f=new JFrame("File Chooser Demo");
mb=new JMenuBar();
f.setJMenuBar(mb);
//*********Found**********
m1=new JMenu("Edit");
mb.add(m1);
mi1=new JMenuItem("Choose Color");
m1.add(mi1);
//*********Found**********
mi1.addActionListener(this);
c=f.getContentPane();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
p=new JPanel();
myColor=Color.red;
p.setBackground(myColor);
c.add("Center",p);
f.setSize(300,300);
f.setVisible(true);
}
public void actionPerformed(ActionEvent e){
cc=new JColorChooser();
//*********Found**********
myColor=cc.showDialog(c,"Choose window background color",Color.white);
p.setBackground(myColor);
}
}
3.16
import javax.swing.*;
//*********Found********
import java.awt.event.*;
import java.io.*;
import java.awt.*;
//*********Found********
public class Java_3 implements ActionListener{
JFrame f;
JTextArea ta;
//*********Found********
JFileChooser fc;
Container c;
File myFile;
public static void main(String args[]){
Java_3 demo = new Java_3();
demo.go();
}
void go(){
f = new JFrame("File Chooser Demo");
//*********Found********
JButton b = new JButton("Open file");
ta = new JTextArea("Where is your file path?",10,30);
//*********Found********
b.addActionListener(this);
c = f.getContentPane();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//*********Found********
f.getContentPane().add("South", b);
f.getContentPane().add("Center",ta);
f.setSize(300,300);
f.setVisible(true);
}
public void actionPerformed(ActionEvent e){
fc = new JFileChooser();
int selected = fc.showOpenDialog(c);
if (selected==JFileChooser.APPROVE_OPTION){
myFile = fc.getSelectedFile();
ta.setText("You have selected file: "+ myFile.getName());
}
}
}
3.17
//*********Found********
public class Java_3 extends Thread{
static RegistrationAgent agent;
static boolean timetoquit=false;
public static void main(String[] args){
agent = new RegistrationAgent();
Thread[] t= new Thread[3];
for (int i=0; i<3; i++){
t[i] = new Java_3();
//*********Found********
t[i].start();
}
}
public void run( ){
//*********Found********
while (!timetoquit){
boolean r = agent.reg();
if (!r)
timetoquit = true;
try{
Thread.sleep(2);
}catch(Exception e){}
}
}
}
class RegistrationAgent {
private int quota = 0;
public boolean reg(){
synchronized(this){
if( quota < 10){
//*********Found********
quota++;
System.out.print(Thread.currentThread().getName());
System.out.println( " Registered one student, and total " + quota
+" students registered.");
return true;
}
else
//*********Found********
return false;
}
}
}
3.18
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.imageio.*;
import javax.swing.*;
public class Java_3 extends JFrame {
private JLabel label;
private JFileChooser fileChooser;
private ImagePanel panel;
public Java_3() {
setTitle("图片浏览器");
setSize(500, 400);
fileChooser = new JFileChooser();
fileChooser.setCurrentDirectory(new File("."));//设置默认路径为当前目录
JMenuBar menuBar = new JMenuBar();
setJMenuBar(menuBar);
JMenu menu = new JMenu("文件");
menuBar.add(menu);
JMenuItem openItem = new JMenuItem("打开图片");
menu.add(openItem);
panel = new ImagePanel();
add(panel);
//*********Found********
openItem.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent event){
int result = fileChooser.showOpenDialog(null);
if(result==JFileChooser.APPROVE_OPTION){
String name = fileChooser.getSelectedFile().getPath();
//*********Found********
panel.setImage(name);
panel.repaint();
}
}
});
JMenuItem exitItem = new JMenuItem("退出图片");
menu.add(exitItem);
exitItem.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent event){
System.exit(0);
}
});
}
public static void main(String[] args) {
//*********Found********
Java_3 frame = new Java_3 ();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//*********Found********
frame.setVisible(true);
}
}
//*********Found********
class ImagePanel extends JPanel {
private Image image;
private int showWidth;
private int showHeight;
public void setImage(String fileName) {
try {
image = ImageIO.read(new File(fileName));
} catch (IOException e) {
e.printStackTrace();
}
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
if (image == null)
return;
int imageWidth = image.getWidth(this);
int imageHeight = image.getHeight(this);
int width = getWidth();
int height = getHeight();
if(imageWidth>width){
this.showWidth = width;
}else{
this.showWidth = imageWidth;
}
if(imageHeight>height){
this.showHeight = height;
}else{
this.showHeight = imageHeight;
}
g.drawImage(image, 0, 0, showWidth, showHeight, null, null);
}
}
3.19
import java.io.*;
import java.lang.Thread;
class MyThread extends Thread{
public int x = 0;
//*********Found********
public void run(){
System.out.println(++x);
}
}
//*********Found********
class RThread implements Runnable{
private int x = 0;
public void run(){
System.out.println(++x);
}
}
public class Java_3 {
public static void main(String[] args) throws Exception{
for(int i=0;i<5;i++){
Thread t = new MyThread();
//*********Found********
t.start();
}
Thread.sleep(1000);
System.out.println();
//*********Found********
RThread r = new RThread();
//*********Found********
for(int i=0;i<5;i++){
Thread t = new Thread(r);
t.start();
}
}
}
3.20
//打印无符号整数位
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Java_3 extends JFrame {
public Java_3(){
super( "打印无符号整数位" );
Container c = getContentPane();
c.setLayout( new FlowLayout() );
c.add( new JLabel( "请输入整数: " ) );
final JTextField output = new JTextField( 33 );
JTextField input = new JTextField( 10 );
input.addActionListener(
new ActionListener() {
//*********Found********
public void actionPerformed( ActionEvent e ){
int val = Integer.parseInt(
e.getActionCommand() );
//*********Found********
output.setText( getBits( val ) );
}
}
);
c.add( input );
c.add( new JLabel( "该数的二进制位表示是" ) );
output.setEditable( false );
//*********Found********
c.add( output );
setSize( 720, 70 );
setVisible(true);
}
private String getBits( int value ){
int displayMask = 1 << 31;
StringBuffer buf = new StringBuffer( 35 );
for ( int c = 1; c <= 32; c++ ) {
buf.append(
( value & displayMask ) == 0 ? '0' : '1' );
value <<= 1;
if ( c % 8 == 0 )
buf.append( ' ' );
}
return buf.toString();
}
public static void main( String args[] ){
Java_3 app = new Java_3();
app.addWindowListener(
new WindowAdapter() {
//*********Found********
public void windowClosing( WindowEvent e ){
System.exit( 0 );
}
}
);
}
}
3.21
import java.io.*;
public class Java_3
{
public static void main(String[] args)
{
Java_3 exceptionExample = new Java_3();
//*********Found**********
try
{
FileInputStream fi = new FileInputStream("C:" + "\\" + "abc.txt");
}
//*********Found**********
catch(FileNotFoundException ex)
{
//*********Found**********
System.out.println(ex.getMessage()+
"请确认文件路径及文件名是否正确！");
}
}
}
3.22
import java.awt.*;
import javax.swing.*;
//*********Found**********
public class Java_3 extends JApplet
{
//*********Found**********
public void init()
{
Container contentPane = getContentPane();
JLabel label = new JLabel("One World One Dream",SwingConstants.CENTER);
label.setFont(new Font("Arial", Font.BOLD, DEFAULT_SIZE));
//*********Found**********
contentPane.add(label);
}
private static final int DEFAULT_SIZE = 24;
}
3.23
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.*;
public class Java_3
{
public static void main(String[] args)
{
JFrame frame = new ImageViewerFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//*********Found**********
frame.setVisible(true);
}
}
class ImageViewerFrame extends JFrame
{
private JLabel label;
private JLabel labelT;
private JFileChooser chooser;
private JComboBox faceCombo;
private static final int DEFAULT_SIZE = 24;
public static final int DEFAULT_WIDTH = 570;
public static final int DEFAULT_HEIGHT = 400;
public ImageViewerFrame()
{
setTitle("ImageViewer");
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
label = new JLabel();
Container contentPane = getContentPane();
contentPane.add(label,BorderLayout.CENTER);
chooser = new JFileChooser();
chooser.setCurrentDirectory(new File("."));
JMenuBar menuBar = new JMenuBar();
setJMenuBar(menuBar);
//*********Found**********
JMenu menu = new JMenu("File");
menuBar.add(menu);
JMenuItem openItem = new JMenuItem("Open");
//*********Found**********
menu.add(openItem);
openItem.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent evt)
{
int r = chooser.showOpenDialog(null);
if(r == JFileChooser.APPROVE_OPTION)
{
//*********Found**********
String name = chooser.getSelectedFile().getPath();
label.setIcon(new ImageIcon(name));
}
}
});
labelT = new JLabel("红军不怕远征难");
labelT.setFont(new Font("隶书", Font.PLAIN, DEFAULT_SIZE));
contentPane.add(labelT, BorderLayout.NORTH );
faceCombo = new JComboBox();
faceCombo.setEditable(true);
faceCombo.addItem("隶书");
faceCombo.addItem("华文新魏");
faceCombo.addItem("华文行楷");
faceCombo.addItem("华文隶书");
faceCombo.addActionListener(new
ActionListener()
{
public void actionPerformed(ActionEvent event)
{
//*********Found**********
labelT.setFont(new Font((String)faceCombo.getSelectedItem(),
Font.PLAIN, DEFAULT_SIZE));
}
});
JPanel comboPanel = new JPanel();
comboPanel.add(faceCombo);
contentPane.add(comboPanel, BorderLayout.SOUTH);
}
}
3.24
import java.awt.event.*;
import java.awt.*;
import java.awt.font.*;
import java.awt.geom.*;
import javax.swing.*;
public class Java_3
{
public static void main(String[] args)
{
FontFrame frame = new FontFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
//*********Found**********
class FontFrame extends JFrame
{
public FontFrame()
{
setTitle("北京 2008");
setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
FontPanel panel = new FontPanel();
Container contentPane = getContentPane();
//*********Found**********
contentPane.add(panel);
}
public static final int DEFAULT_WIDTH = 400;
public static final int DEFAULT_HEIGHT = 250;
}
class FontPanel extends JPanel
{
public FontPanel()
{
JButton yellowButton = new JButton("Yellow");
JButton blueButton = new JButton("Blue");
JButton redButton = new JButton("Green");
add(yellowButton);
add(blueButton);
add(redButton);
ColorAction yellowAction = new ColorAction(Color.YELLOW);
ColorAction blueAction = new ColorAction(Color.BLUE);
ColorAction greenAction = new ColorAction(Color.GREEN);
yellowButton.addActionListener(yellowAction);
blueButton.addActionListener(blueAction);
redButton.addActionListener(greenAction);
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
String message = "同一个世界，同一个梦想！";
Font f = new Font("隶书", Font.BOLD, 27);
g2.setFont(f);
FontRenderContext context = g2.getFontRenderContext();
Rectangle2D bounds = f.getStringBounds(message, context);
double x = (getWidth() - bounds.getWidth()) / 2;
double y = (getHeight() - bounds.getHeight()) / 2;
double ascent = -bounds.getY();
double baseY = y + ascent;
g2.setPaint(Color.RED);
g2.drawString (message, (int)x, (int)(baseY));
}
//*********Found**********
private class ColorAction implements ActionListener
{
public ColorAction(Color c)
{
BackgroundColor = c;
}
//*********Found**********
public void actionPerformed(ActionEvent event)
{
setBackground(BackgroundColor);
}
private Color BackgroundColor;
}
}
3.25
import javax.swing.*;
import java.awt.event.*;
import java.io.*;
import java.awt.*;
public class Java_3 implements ActionListener
{
private JFrame frame;
private JButton button;
private JButton saveButton;
private JTextArea textArea;
private JFileChooser dia;
private JPanel buttonPanel;
public void initGUI()
{
//*********Found**********
frame=new JFrame("file chooser");
button=new JButton("open file");
button.setActionCommand("open");
//*********Found**********
button.addActionListener(this);
saveButton=new JButton("save file");
saveButton.setActionCommand("save");
//*********Found**********
saveButton.addActionListener(this);
textArea=new JTextArea("",10,10);
buttonPanel=new JPanel();
dia=new JFileChooser();
frame.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
});
buttonPanel.add(button);
buttonPanel.add(saveButton);
frame.getContentPane().add(buttonPanel,BorderLayout.NORTH);
frame.getContentPane().add(textArea,BorderLayout.CENTER);
frame.setSize(300,300);
//*********Found**********
frame.setVisible(true);
}
//*********Found**********
public void actionPerformed(ActionEvent event)
{
if(event.getActionCommand().equals("open"))
{
dia.showOpenDialog( frame );
dia.setVisible(true);
File file=dia.getSelectedFile();
String fileName=file.getAbsolutePath();
textArea.append("path of selected file: "+fileName+"\r\n");
}
else if(event.getActionCommand().equals("save"))
{
dia.showSaveDialog(frame);
dia.setVisible(true);
File file=dia.getSelectedFile();
String fileName=file.getAbsolutePath();
textArea.append("path of saved file: "+fileName+"\r\n");
}
}
public static void main(String args[])
{
Java_3 example=new Java_3();
example.initGUI();
}
}
3.26
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
//*********Found**********
public class Java_3 extends MouseAdapter implements ActionListener
{
//*********Found**********
private JPopupMenu pop;
private JMenu subPop;
private JMenuItem color;
private JMenuItem exit;
private JMenuItem red;
private JMenuItem blue;
private JTextArea textArea;
private JFrame frame;
public void initGUI()
{
pop=new JPopupMenu();
subPop=new JMenu("color");
//*********Found**********
red=new JMenuItem("red");
red.addActionListener(this);
blue=new JMenuItem("blue");
blue.addActionListener(this);
subPop.add(red);
subPop.add(blue);
exit=new JMenuItem("exit");
exit.addActionListener(this);
pop.add(subPop);
pop.add(exit);
frame=new JFrame("popup frame");
textArea=new JTextArea("",10,10);
textArea.addMouseListener(this);
//*********Found**********
frame.getContentPane().add(textArea);
frame.setSize(300,300);
frame.setVisible(true);
frame.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
});
}
public void actionPerformed(ActionEvent event)
{
if(event.getSource()==red)
{
//*********Found**********
textArea.setForeground(Color.red);
textArea.setText("red menu is selected");
}
else if(event.getSource()==blue)
{
textArea.setForeground(Color.blue);
textArea.setText("blue menu is selected");
}
else if(event.getSource()==exit)
{
frame.setVisible(false);
System.exit(0);
}
}
public void mousePressed(MouseEvent e)
{
if(e.getModifiers()==e.BUTTON3_MASK)
{
pop.show(e.getComponent(),e.getX(),e.getY());
}
}
public static void main(String args[])
{
Java_3 example=new Java_3();
example.initGUI();
}
}
3.27
import java.awt.Graphics;
import javax.swing.JApplet;
//*********Found**********
public class Java_3 extends JApplet {
//*********Found**********
public void paint(Graphics g){
int counter = 1;
do {
//*********Found**********
g.drawOval( 110 - counter * 10, 110 - counter * 10,
counter * 20, counter * 20 );
//*********Found**********
counter++;
} while (counter<=10);
}
}
3.28
//*********Found**********
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
//*********Found**********
public class Java_3 extends MouseAdapter implements ActionListener
{
//*********Found**********
private JPopupMenu pop;
private JMenu subPop;
private JMenuItem color;
private JMenuItem exit;
private JMenuItem red;
private JMenuItem blue;
private JTextArea textArea;
private JFrame frame;
public void initGUI()
{
pop=new JPopupMenu();
subPop=new JMenu("color");
red=new JMenuItem("red");
red.addActionListener(this);
blue=new JMenuItem("blue");
blue.addActionListener(this);
subPop.add(red);
subPop.add(blue);
exit=new JMenuItem("exit");
exit.addActionListener(this);
pop.add(subPop);
pop.add(exit);
//*********Found**********
frame=new JFrame("popupframe");
textArea=new JTextArea("",10,10);
textArea.addMouseListener(this);
frame.getContentPane().add(textArea);
frame.setSize(300,300);
frame.setVisible(true);
frame.addWindowListener(new WindowAdapter()
{
//*********Found**********
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
});
}
public void actionPerformed(ActionEvent event)
{
if(event.getSource()==red)
{
textArea.setForeground(Color.red);
textArea.setText("red menu is selected");
}
else if(event.getSource()==blue)
{
textArea.setForeground(Color.blue);
textArea.setText("blue menu is selected");
}
else if(event.getSource()==exit)
{
frame.setVisible(false);
System.exit(0);
}
}
public void mousePressed(MouseEvent e)
{
if(e.getModifiers()==e.BUTTON3_MASK)
{
pop.show(e.getComponent(),e.getX(),e.getY());
}
}
public static void main(String args[])
{
Java_3 example=new Java_3();
example.initGUI();
}
}
3.29
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;
public class Java_3
{
public static void main(String[] args)
{
ExceptTestFrame frame = new ExceptTestFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
class ExceptTestFrame extends JFrame
{
public ExceptTestFrame()
{
setTitle("ExceptTest");
Container contentPane = getContentPane();
ExceptTestPanel panel = new ExceptTestPanel();
//*********Found********
contentPane.add(panel);
pack();
}
}
class ExceptTestPanel extends Box
{
public ExceptTestPanel()
{
super(BoxLayout.Y_AXIS);
group = new ButtonGroup();
addRadioButton("整数被零除", new
ActionListener()
{
//*********Found********
public void actionPerformed(ActionEvent event)
{
a[1] = 1 / (a.length - a.length);
}
});
textField = new JTextField(30);
add(textField);
}
//*********Found********
private void addRadioButton(String s, ActionListener listener)
{
JRadioButton button = new JRadioButton(s, false)
{
protected void fireActionPerformed(ActionEvent event)
{
try
{
textField.setText("No exception");
super.fireActionPerformed(event);
}
catch (Exception exception)
{
//*********Found********
textField.setText(exception.toString());
}
}
};
button.addActionListener(listener);
add(button);
group.add(button);
}
private ButtonGroup group;
private JTextField textField;
private double[] a = new double[10];
}
3.30
import java.awt.*;
import javax.swing.*;
//*********Found**********
public class Java_3 extends JApplet{
//*********Found**********
public void init(){
Container contentPane = getContentPane();
JLabel label = new JLabel("Java的诞生是对传统计算模式的挑战！",
SwingConstants.CENTER);
//*********Found**********
contentPane.add(label);
}
}
3.31
import javax.swing.JOptionPane;
public class Java_3 {
public static void main( String args[] ){
String firstNumber, //存储第1个输入数据
secondNumber, //存储第2个输入数据
//*********Found********
result; //字符串输出
int number1, //用来比较的第1个int型数据
number2; //用来比较的第2个int型数据
//以字符串格式读输入数据
firstNumber =
JOptionPane.showInputDialog( "请输入第1个整数:" );
secondNumber =
JOptionPane.showInputDialog( "请输入第2个整数:" );
//将字符串转换为int整数
//*********Found********
number1 = Integer.parseInt( firstNumber );
//*********Found********
number2 = Integer.parseInt( secondNumber );
//用空字符串初始化结果变量
result = "";
if ( number1 == number2 )
result = number1 + " == " + number2;
if ( number1 != number2 )
result = number1 + " != " + number2;
if ( number1 < number2 )
result = result + "\n" + number1 + " < " + number2;
if ( number1 > number2 )
result = result + "\n" + number1 + " > " + number2;
if ( number1 <= number2 )
result = result + "\n" + number1 + " <= " + number2;
if ( number1 >= number2 )
result = result + "\n" + number1 + " >= " + number2;
//显示结果
JOptionPane.showMessageDialog(
null, result, "比较结果",
JOptionPane.INFORMATION_MESSAGE);
//*********Found********
System.exit( 0 );
}
}
3.32
import java.awt.Graphics;
import javax.swing.*;
//*********Found**********
public class Java_3 extends JApplet{
double sum; //存和的变量
//*********Found**********
public void init(){
String firstNumber, //输入第1个字符串格式的数
secondNumber; //输入第2个字符串格式的数
double number1, //加数
number2; //被加数
//读入第1个输入的数
firstNumber =
JOptionPane.showInputDialog(
"Enter first floating-point value" );
//读入第2个输入的数
secondNumber =
JOptionPane.showInputDialog(
"Enter second floating-point value" );
//将字符串数据转换成双字长类型
number1 = Double.parseDouble( firstNumber );
number2 = Double.parseDouble( secondNumber );
//数据相加
sum = number1 + number2;
}
public void paint( Graphics g ) {
//用g.drawString给结果
g.drawRect( 15, 10, 270, 20 );
g.drawString( "数相加之和为:" + sum, 25, 25 );
}
}
<html>
//*********Found**********
<applet code="Java_3.class" width=300 height=50>
</applet>
</html>
3.33
import java.awt.*;
import javax.swing.*;
//*********Found**********
public class Java_3 extends JApplet{
JTextArea outputArea;
public void init(){
outputArea = new JTextArea();
//*********Found**********
Container c = getContentPane();
//*********Found**********
c.add( outputArea );
//计算0至10的阶乘
for ( long i = 0; i <= 10; i++ )
outputArea.append(
i + "! = " + factorial( i ) + "\n" );
}
//阶乘的递归定义
public long factorial( long number ){
if ( number <= 1 )
return 1;
else
return number * factorial( number - 1 );
}
}
3.34
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
//*********Found**********
public class Java_3 extends JApplet implements ActionListener{
JLabel prompt;
JTextField input;
public void init(){
Container c = getContentPane();
c.setLayout( new FlowLayout() );
//*********Found**********
prompt = new JLabel( "输入球半径: " );
input = new JTextField( 10 );
//*********Found**********
input.addActionListener(this);
c.add( prompt );
c.add( input );
}
public void actionPerformed( ActionEvent e ){
double radius =
Double.parseDouble( e.getActionCommand() );
showStatus( "体积 " + sphereVolume( radius ) );
}
public double sphereVolume( double radius ){
double volume =
( 4.0 / 3.0 ) * Math.PI * Math.pow( radius, 3 );
return volume;
}
}
3.35
import java.lang.*;
import java.util.*;
public class Java_3{
public static void main(String[ ]args){
int bound=100;
int i=0,j=0,counter=0,k=0;
int temp=0;
boolean first=true;
for(i=1;i<bound;i++){
for(j=1;j<bound;j++){
//*********Found**********
temp=i*i +5*j*j;
k=(int)Math.sqrt(temp);
//*********Found**********
if(k<bound && k*k == temp ){
if(first){
System.out.println("The first component: ("+i+", "+j+", "+k+")");
//*********Found**********
first=false;
}
//*********Found**********
counter++;
}
};
}
System.out.print("Total number is: "+counter);
System.exit(0);
}
}
3.36
import java.lang.*;
import java.util.*;
public class Java_3{
public static void main(String[ ]args){
int bound=100;
int i=0,j=0,counter=0,k=0;
int temp=0;
boolean first=true;
for(i=1;i<bound;i++){
for(j=1;j<bound;j++){
//*********Found**********
temp=i*i +5*j*j;
k=(int)Math.sqrt(temp);
//*********Found**********
if(k<bound && k*k == temp ){
if(first){
System.out.println("The first component: ("+i+", "+j+", "+k+")");
//*********Found**********
first=false;
}
//*********Found**********
counter++;
}
};
}
System.out.print("Total number is: "+counter);
System.exit(0);
}
}
3.37
import java.awt.*;
import java.awt.event.* ;
//*********Found********
import javax.swing.*;
//*********Found********
public class Java_3 implements ActionListener{
public static void main(String args[ ]){
Java_3 tb = new Java_3();
//*********Found********
JFrame f = new JFrame("Button Test");
f.setSize(200,100);
f.setLayout(new FlowLayout(FlowLayout.CENTER));
JButton b = new JButton("Press the Button!"); /JButton
//*********Found********
b.addActionListener(tb);
//*********Found********
f.add(b);
f.addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e){
System.exit(0);
}
});
f.setVisible(true) ;
}
//*********Found********
public void actionPerformed(ActionEvent e){
JFrame fr = new JFrame("An Other");
fr.setBackground(Color.green);
fr.add(new JLabel("This frame shows when "+"pressing the button in Button Test"));
fr.addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e){
System.exit(0);
}
});
fr.pack();
fr.setVisible(true) ;
}
}
3.38
import java.io.*;
import java.util.*;
public class Java_3
{
//*********Found**********
public static void main (String args[]) throws IOException {
FileOutputStream unbufStream = new FileOutputStream("test.one");
BufferedOutputStream bufStream = new BufferedOutputStream(
//*********Found**********
new FileOutputStream ("test.two"));
System.out.println();
System.out.println("这是一个测试缓冲流和非缓冲流速度的程序。");
System.out.println();
//*********Found**********
int flag = time(unbufStream)-time(bufStream);
if(flag > 0) {
System.out.println("测试结果：缓冲流的传输速度快于非缓冲流。");
System.out.println();
}
else
System.out.println("测试结果：缓冲流的传输速度慢于非缓冲流。");
}
//*********Found**********
static int time(OutputStream out) throws IOException {
//*********Found**********
Date then = new Date();
for (int i=0; i<1000; i++) {
out.write(1);
}
//*********Found**********
out.close ();
return (int)((new Date()).getTime() - then.getTime());
}
}
3.39
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
//**********found**********
public class Java_3 extends JFrame {
private JTextField username;
private JPasswordField password;
private JLabel jl1;
private JLabel jl2;
private JLabel jl3;
private JLabel jl4;
private JButton bu1;
private JButton bu2;
private JButton bu3;
private JCheckBox jc1;
private JCheckBox jc2;
private JComboBox jcb;
public Java_3() {
this.setTitle("QQ2022正式版");
init();
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// 设置布局方式为绝对定位
this.setLayout(null);
this.setBounds(0, 0, 355, 265);
// 设置窗体的标题图标
Image image = new ImageIcon("a.png").getImage();
this.setIconImage(image);
// 窗体大小不能改变
this.setResizable(false);
// 居中显示
this.setLocationRelativeTo(null);
//**********found**********
this.setVisible(true);
}
public void init() {
Container con = this.getContentPane();
jl1 = new JLabel();
// 设置背景图片
Image image1 = new ImageIcon("background.jpg").getImage();
jl1.setIcon(new ImageIcon(image1));
jl1.setBounds(0, 0, 355, 265);
jl2 = new JLabel();
Image image2 = new ImageIcon("a.gif").getImage();
jl2.setIcon(new ImageIcon(image2));
jl2.setBounds(40, 95, 50, 60);
//**********found**********
username = new JTextField();
username.setBounds(50, 50, 150, 20);
jl3 = new JLabel("注册账号");
jl3.setBounds(210, 50, 70, 20);
password = new JPasswordField();
password.setBounds(50, 80, 150, 20);
jl4 = new JLabel("找回密码");
jl4.setBounds(210, 80, 70, 20);
jc1 = new JCheckBox("记住密码");
jc1.setBounds(125, 135, 80, 15);
jc2 = new JCheckBox("自动登录");
jc2.setBounds(215, 135, 80, 15);
jcb = new JComboBox();
jcb.addItem("在线");
jcb.addItem("隐身");
jcb.addItem("离开");
jcb.setBounds(40, 135, 55, 20);
bu1 = new JButton("登录");
bu1.setBounds(250, 200, 65, 20);
bu2 = new JButton("多账号");
bu2.setBounds(25, 200, 75, 20);
bu3 = new JButton("设置");
bu3.setBounds(140, 200, 65, 20);
bu3.addActionListener(new ActionListener() {
//**********found**********
public void actionPerformed(ActionEvent e) {
if (jc1.isSelected()==true)
JOptionPane.showConfirmDialog(null,"确定记住密码吗?");
}
});
// 所有组件用容器装载
jl1.add(jl2);
jl1.add(jl3);
jl1.add(jl4);
jl1.add(jc1);
jl1.add(jc2);
jl1.add(jcb);
jl1.add(bu1);
jl1.add(bu2);
jl1.add(bu3);
con.add(jl1);
con.add(username);
con.add(password);
}
//**********found**********
public static void main (String[] args) {
Java_3 qq = new Java_3();
}
}
3.40
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Java_3 {
public static void main(String[] args) {
JFrame frame = new JFrame("Mouse Demo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new MousePanel());
frame.pack();
frame.setVisible(true);
}
}
//*********Found**********
class MousePanel extends JPanel {
private JLabel b;
public MousePanel() {
b = new JLabel(" 起始状态 ");
setLayout(new BorderLayout());
add(b, BorderLayout.SOUTH);
addMouseMotionListener(new MouseMotion());
setPreferredSize(new Dimension(300, 200));
}
//*********Found**********
private class MouseMotion extends MouseMotionAdapter {
public void mouseMoved(MouseEvent e) {
//*********Found**********
b.setText(" 鼠标当前位置: "+ e.getX()+ " , " + e.getY());
}
}
}
3.41
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Java_3 extends JFrame implements ActionListener{
private double x = 0;
private double y = 0;
JTextField xval = new JTextField(10);
JButton calcBtn = new JButton("计算");
JTextArea result = new JTextArea(10,20);
void initFrame(){
Container content = getContentPane();
content.setLayout(new BorderLayout());
JPanel calcPanel = new JPanel();
calcPanel.setLayout(new FlowLayout());
calcPanel.add(new JLabel("角度"));
calcPanel.add(xval);
//***************************Found*********************
calcPanel.add(calcBtn);
content.add(calcPanel,"North");
//***************************Found*********************
calcBtn.addActionListener(this);
content.add(result,"Center");
//***************************Found*********************
result.setEditable(false);
}
public Java_3(){
super("计算正弦函数");
setSize(500,200);
initFrame();
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void actionPerformed(ActionEvent e){
//***************************Found*********************
if (e.getSource()==calcBtn){
x = Double.parseDouble(xval.getText())/180*3.14;
y = Math.sin(x);
//***************************Found*********************
String str="sin("+ xval.getText() +"*3.14/180)= "+y+'\n';
//***************************Found*********************
result.append(str);
}
}
public static void main(String[] args){
new Java_3();
}
}
3.42
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
//**************found*****************
public class Java_3 extends Frame implements ItemListener{
Color color = Color.blue;
CheckboxGroup cg;
Checkbox cb1,cb2,cb3;
public Java_3(){
cg = new CheckboxGroup();
setSize(300,300);
cb1 = new Checkbox("blue",cg,true);
cb2 = new Checkbox("red",cg,true);
cb3 = new Checkbox("green",cg,true);
cg.setSelectedCheckbox(cb1);
add(cb1); add(cb2); add(cb3);
cb1.addItemListener(this);
cb2.addItemListener(this);
//**************found*****************
cb3.addItemListener(this);
}
public void itemStateChanged(ItemEvent e){
if(e.getSource()==cb1)
color=Color.blue;
if(e.getSource()==cb2)
color=Color.red;
if(e.getSource()==cb3)
color=Color.green;
repaint();
}
class MyEvent1 extends WindowAdapter {
public void windowClosing(WindowEvent e){
System.exit(0);
}
}
class MyEvent2 extends ComponentAdapter {
public void componentResized(ComponentEvent e){
repaint();
}
}
//**************found*****************
public void paint(Graphics g) {
int w = getWidth(),h=getHeight();
int x0 = w/2,y0 = h/2;
g.setColor(color);
g.drawLine(x0,0,x0,h);
g.drawLine(0,y0,w,y0);
double pi = 3.1415926,angle,rou;
int r,i,x,y;
for(r=10;r<200;r+=20){
for(i=0;i<1023;i++){
angle = i * pi/512;
rou = r * Math.sin(2*angle);
x = (int)Math.round(rou*Math.cos(angle));
y = (int)Math.round(rou*Math.sin(angle));
g.drawOval(x0+x,y0+y,1,1);
}
}
}
public static void main(String[] args){
Java_3 f = new Java_3();
MyEvent1 me1 = f.new MyEvent1();
MyEvent2 me2 = f.new MyEvent2();
//**************found*****************
f.setTitle("四叶玫瑰线");
f.setLayout(new FlowLayout());
f.addWindowListener(me1);
f.addComponentListener(me2);
//**************found*****************
f.setVisible(true);
}
}
3.43
import java.io.*;
import java.awt.*;
import java.awt.event.* ;
//**********found**********
import javax.swing.*;
public class Java_3 implements ActionListener {
JTextArea ta;
JFrame f ;
JLabel label;
JButton bs,br;
public static void main(String[ ] args){
Java_3 t = new Java_3();
t.go();
}
void go(){
f = new JFrame("Save data");
f.setSize( 20, 400);
//**********found**********
f.setLayout(new FlowLayout());
label = new JLabel("请输入需要保存的文本 ：");
ta = new JTextArea(3,20);
bs = new JButton("保存");
br = new JButton("读取");
f.add(label);
f.add(ta);
f.add(bs);
f.add(br);
//**********found**********
bs.addActionListener(this);
//**********found**********
br.addActionListener(new ReadFile());
f.setSize(400,400);
f.pack( );
f.setVisible(true) ;
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void actionPerformed(ActionEvent event){
try{
FileWriter out = new FileWriter("out.txt");
String str = ta.getText();
//**********found**********
out.write(str);
out.close();
} catch( Exception e){
}
ta.setText(" ");
}
class ReadFile implements ActionListener{
public void actionPerformed(ActionEvent event){
String cc;
StringBuffer str = new StringBuffer("");
try{
FileReader in = new FileReader("out.txt");
//**********found**********
BufferedReader bin= new BufferedReader(in);
while ( (cc = bin.readLine())!= null)
str.append(cc);
bin.close();
ta.setText(str.toString());
} catch( Exception e){ }
}
}
}
3.44
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
//**********found**********
public class Java_3 extends JFrame {
private JTextField username;
private JPasswordField password;
private JLabel jl1;
private JLabel jl2;
private JLabel jl3;
private JLabel jl4;
private JButton bu1;
private JButton bu2;
private JButton bu3;
private JCheckBox jc1;
private JCheckBox jc2;
private JComboBox jcb;
public Java_3() {
this.setTitle("QQ2022正式版");
//**********found**********
init();
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// 设置布局方式为绝对定位
this.setLayout(null);
this.setBounds(0, 0, 355, 265);
// 设置窗体的标题图标
Image image = new ImageIcon("a.png").getImage();
this.setIconImage(image);
// 窗体大小不能改变
this.setResizable(false);
// 居中显示
this.setLocationRelativeTo(null);
this.setVisible(true);
}
public void init() {
//**********found**********
Container con = this.getContentPane();
jl1 = new JLabel();
// 设置背景图片
Image image1 = new ImageIcon("background.jpg").getImage();
jl1.setIcon(new ImageIcon(image1));
jl1.setBounds(0, 0, 355, 265);
jl2 = new JLabel();
Image image2 = new ImageIcon("a.gif").getImage();
jl2.setIcon(new ImageIcon(image2));
jl2.setBounds(40, 95, 50, 60);
username = new JTextField();
username.setBounds(50, 50, 150, 20);
jl3 = new JLabel("注册账号");
jl3.setBounds(210, 50, 70, 20);
password = new JPasswordField();
password.setBounds(50, 80, 150, 20);
jl4 = new JLabel("找回密码");
jl4.setBounds(210, 80, 70, 20);
jc1 = new JCheckBox("记住密码");
jc1.setBounds(125, 135, 80, 15);
jc2 = new JCheckBox("自动登录");
jc2.setBounds(215, 135, 80, 15);
jcb = new JComboBox();
jcb.addItem("在线");
jcb.addItem("隐身");
jcb.addItem("离开");
jcb.setBounds(40, 135, 55, 20);
//**********found**********
bu1 = new JButton("登录");
bu1.setBounds(250, 200, 65, 20);
//**********found**********
bu1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String str=e.getActionCommand();
if("登录".equals(str)){
String getName =username.getText();
JOptionPane.showConfirmDialog(null, "您输入的用户名是"+getName);
}
}
});
bu2 = new JButton("多账号");
bu2.setBounds(25, 200, 75, 20);
bu3 = new JButton("设置");
bu3.setBounds(140, 200, 65, 20);
// 所有组件用容器装载
jl1.add(jl2);
jl1.add(jl3);
jl1.add(jl4);
jl1.add(jc1);
jl1.add(jc2);
jl1.add(jcb);
jl1.add(bu1);
jl1.add(bu2);
jl1.add(bu3);
con.add(jl1);
con.add(username);
con.add(password);
}
public static void main(String[] args) {
Java_3 qq = new Java_3();
}
}
3.45
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Java_3 extends JFrame implements ActionListener{
JTextField nval = new JTextField(10);
//**********Found**********
JButton calcBtn = new JButton("计算") ;
JTextArea result = new JTextArea(10,20);
void initFrame(){
Container content = getContentPane();
JPanel calcPanel = new JPanel();
calcPanel.add(new JLabel("N值"));
//**********Found**********
calcPanel.add(nval);
calcPanel.add(calcBtn) ;
content.add(calcPanel,"North");
//**********Found**********
calcBtn.addActionListener(this);
content.add(result,"Center");
result. setEditable(false) ;
}
public Java_3(){
super("计算素数");
setSize(500,200);
initFrame();
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void actionPerformed(ActionEvent e){
if(e.getSource()==calcBtn){
int N=Integer.parseInt(nval.getText());
int [] prime=new int[N/3+2];
prime[0]=2;prime[1]=3;
int k=2;
for(int m=5;m<=N;m+=2){
int j=1,isprime=1;
int kk=Math.round((float)Math.sqrt(m));
while(prime[j]<=kk){
if(m%prime[j]==0){
//**********Found**********
isprime=0;
break;
}else
//**********Found**********
j++ ;
}
if(isprime==1) prime[k++]=m;
}
//**********Found**********
String str="Total prime number: "+k ;
result.setText("");
result.append(str );
}
}
public static void main(String[] args){
new Java_3();
}
}
3.46
//**********Found**********
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.net.*;
public class Java_3 extends JFrame {
public Java_3() {
//**********Found**********
setTitle("三国攻略游戏");
setBounds(650, 350, 650, 400);
setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
Container container = getContentPane();
setLayout(new BorderLayout());
JPanel p1 = new JPanel();
JLabel bxx = new JLabel("北京天下第一攻略游戏有限公司荣誉出品 ");
p1.add(bxx);
this.add(BorderLayout.SOUTH, p1);
bxx.setBackground(Color.white);
//**********Found**********
JMenuBar m = new JMenuBar();
setJMenuBar(m);
JMenu m1 = new JMenu("魏国");
JMenu m2 = new JMenu("蜀国");
JMenu m3 = new JMenu("吴国");
JMenu n1 = new JMenu("曹操");
JMenu n2 = new JMenu("夏侯惇");
JMenu n3 = new JMenu("司马懿");
JMenu n4 = new JMenu("刘备");
JMenu n5 = new JMenu("关羽");
JMenu n6 = new JMenu("赵云");
JMenuItem n31 = new JMenuItem("指挥能力");
JMenuItem n32 = new JMenuItem("战斗技能");
JMenuItem n33 = new JMenuItem("管理能力");
JMenuItem n21 = new JMenuItem("指挥能力");
JMenuItem n22 = new JMenuItem("战斗技能");
JMenuItem n23 = new JMenuItem("管理能力");
m.add(m1);
m.add(m2);
m.add(m3);
m1.add(n1);
m1.add(n2);
m1.add(n3);
m2.add(n4);
m2.add(n5);
m2.add(n6);
n4.add(n31);
n4.add(n32);
n4.add(n33);
n1.add(n21);
n1.add(n22);
n1.add(n23);
//**********Found**********
n31.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
JLabel l1 = new JLabel();
JLabel l2 = new JLabel();
JDialog dialog = new JDialog();
dialog.setLayout(new GridLayout(2, 1, 5, 5));
dialog.add(l1);
dialog.add(l2);
dialog.setModal(true);
dialog.setSize(354, 200);
dialog.setLocationByPlatform(true);
dialog.setTitle("刘备指挥能力");
dialog.setVisible(true);
}
});
//**********Found**********
n32.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
JLabel l1 = new JLabel();
JLabel l2 = new JLabel();
JDialog dialog = new JDialog();
dialog.setLayout(new GridLayout(2, 1, 5, 5));
dialog.add(l1);
dialog.add(l2);
dialog.setModal(true);
dialog.setSize(500, 400);
dialog.setLocationByPlatform(true);
dialog.setTitle("刘备战斗技能");
dialog.setVisible(true);
}
});
n33.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
JLabel l1 = new JLabel();
JLabel l2 = new JLabel();
JDialog dialog = new JDialog();
dialog.setLayout(new GridLayout(2, 1, 10, 10));
dialog.add(l1);
dialog.add(l2);
dialog.setModal(true);
dialog.setSize(500, 400);
dialog.setLocationByPlatform(true);
dialog.setTitle("刘备管理能力");
dialog.setVisible(true);
}
});
//**********Found**********
setVisible(true);
}
public static void main(String[] args) {
new Java_3();
}
}
3.47
import java.io.*;
import java.awt.*;
import java.awt.event.* ;
import javax.swing.*;
//**********Found**********
public class Java_3 implements ActionListener {
JTextArea ta1,ta2;
JFrame f ;
JLabel label1,label2;
JButton bs,br;
//**********Found**********
char[] aa={'A','B','C','D','E'};
String ss;
public static void main(String args[ ]){
Java_3 t = new Java_3();
t.go();
}
void go(){
f = new JFrame("Data Input and Output");
f.setSize( 20, 200);
//**********Found**********
f.setLayout(new GridLayout(2,3,5,5));
label1 = new JLabel(" 数组内容：");
ta1 = new JTextArea(2,20);
ss=new String(aa);
ta1.setText(ss);
bs = new JButton("保存");
label2 = new JLabel(" 已保存：");
ta2 = new JTextArea(2,20);
br = new JButton("读取");
f.add(label1);
f.add(ta1);
f.add(bs);
f.add(label2);
f.add(ta2);
f.add(br);
bs.addActionListener(this);
//**********Found**********
br.addActionListener( new ReadFile() );
f.setSize(400,400);
f.pack( );
f.setVisible(true) ;
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void actionPerformed(ActionEvent event){
try{
DataOutputStream out = new DataOutputStream(new FileOutputStream("out.txt"));
for (int i=0; i<=aa.length; i++)
//**********Found**********
out.writeChar(aa[i]);
out.close();
} catch( Exception e){ }
}
class ReadFile implements ActionListener{
public void actionPerformed(ActionEvent event){
int i=0;
char c;
char[] a1= new char[50];
String str ;
DataInputStream in;
try{
//**********Found**********
in = new DataInputStream( new FileInputStream("out.txt"));
while ( i<aa.length){
c = in.readChar();
a1[i++]=c;
}
in.close();
str = new String(a1);
ta2.setText(str);
} catch( Exception e){ }
}
}
}
3.48
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Java_3 extends JFrame implements ActionListener
{
private double x=0;
private double y=0;
JTextField xval1 = new JTextField(10);
JTextField xval2 = new JTextField(10);
JButton calcBtn = new JButton("计算");
JTextArea result = new JTextArea(10,20);
void initFrame()
{
Container content = getContentPane();
content.setLayout(new BorderLayout());
JPanel calcPanel = new JPanel();
calcPanel.setLayout(new FlowLayout());
calcPanel.add(new JLabel("角度1"));
calcPanel.add(xval1);
//***************************Found*********************
calcPanel.add( new JLabel("角度2") );
calcPanel.add(xval2);
//***************************Found*********************
calcPanel.add(calcBtn);
content.add(calcPanel,"North");
calcBtn.addActionListener(this);
content.add(result,"Center");
//***************************Found*********************
result.setEditable(false);
}
public Java_3()
{
super("计算两角和余弦函数");
setSize(500,200);
initFrame();
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void actionPerformed(ActionEvent e)
{
//***************************Found*********************
if (e.getSource()== calcBtn ){
x=Double.parseDouble(xval1.getText())/180*3.1415926;
//***************************Found*********************
x=x+Double.parseDouble( xval2.getText() )/180*3.1415926;
//***************************Found*********************
y= Math.cos(x);
String str="cos( ("+xval1.getText()+"+"+xval2.getText()+") *3.1415926/180)= "+y+'\n';
result. append(str) ;
}
}
public static void main(String[] args)
{
new Java_3();
}
}
3.49
import java.io.*;
//**********Found**********
import java.awt.event.* ;
import javax.swing.*;
public class Java_3 {
static JTextArea ta;
JFrame frame ;
public static void main(String args[ ]){
Java_3 t = new Java_3();
//**********Found**********
t.frameAndMenu();
}
void frameAndMenu(){
frame = new JFrame();
frame.setSize(400,150);
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
JMenuBar menuBar = new JMenuBar();
//**********Found**********
JMenu menu = new JMenu("Menu");
JMenuItem menuItemReadFile = new JMenuItem("ReadFile");
//**********Found**********
menuItemReadFile.addActionListener( new ReadFile());
JMenuItem menuItemExit = new JMenuItem("Exit");
menuItemExit.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.exit(0);
}
});
menu.add(menuItemReadFile);
menu.add(menuItemExit);
menuBar.add(menu);
frame.setJMenuBar(menuBar);
ta = new JTextArea(10,100);
frame.add(ta);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocation(600, 300);
frame.setVisible(true);
}
}
//**********Found**********
class ReadFile implements ActionListener{
public void actionPerformed(ActionEvent event){
String cc;
StringBuffer str = new StringBuffer("");
try{
FileReader in = new FileReader("java3.txt");
//**********Found**********
BufferedReader bin= new BufferedReader(in);
while ( (cc = bin.readLine())!= null)
str.append(cc);
bin.close();
Java_3.ta.setText(str.toString());
} catch( Exception e){ }
}
}
3.50
//**********Found**********
import java.io.*;
import java.awt.event.* ;
import javax.swing.*;
//**********Found**********
public class Java_3 implements ActionListener{
JTextArea ta;
JFrame frame ;
public static void main(String args[ ]){
Java_3 fr = new Java_3();
fr.frameAndMenu();
}
void frameAndMenu(){
frame = new JFrame();
frame.setSize(200,150);
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
JMenuBar menuBar = new JMenuBar();
JMenu menu = new JMenu("Menu");
JMenuItem menuItemSaveFile = new JMenuItem("SaveFile");
//**********Found**********
menuItemSaveFile.addActionListener(this);
JMenuItem menuItemExit = new JMenuItem("Exit");
//**********Found**********
menuItemExit.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.exit(0);
}
});
menu.add(menuItemSaveFile);
menu.add(menuItemExit);
//**********Found**********
menuBar.add(menu);
frame.setJMenuBar(menuBar);
ta = new JTextArea(3,20);
frame.add(ta);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocation(600, 300);
frame.setVisible(true);
}
public void actionPerformed(ActionEvent event){
try{
FileWriter out = new FileWriter("java_3.txt");
//**********Found**********
String str = ta.getText();
out.write(str);
out.close();
} catch( Exception e){ }
ta.setText(" ");
}
}
3.51
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Java_3 extends JFrame implements ActionListener{
private double x=0;
private double y=0;
JTextField xval = new JTextField(10);
JButton calcBtn = new JButton("计算");
JTextArea result = new JTextArea(10,20);
boolean isAngleRad=true;
JButton angleUnitBtn=new JButton("设成角度");
void initFrame(){
Container content = getContentPane();
content.setLayout(new BorderLayout());
JPanel calcPanel = new JPanel();
calcPanel.setLayout(new FlowLayout());
//***************************Found*********************
calcPanel.add( new JLabel("角的值") );
calcPanel.add(xval);
calcPanel.add(calcBtn) ;
calcPanel.add(angleUnitBtn);
content.add(calcPanel,"North");
calcBtn.addActionListener(this);
//***************************Found*********************
angleUnitBtn.addActionListener(this) ;
content.add(result,"Center");
//***************************Found*********************
result.setEditable(false);
}
public Java_3(){
super("计算余弦函数");
setSize(500,200);
initFrame();
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void actionPerformed(ActionEvent e){
if (e.getSource()== calcBtn){
String str;
if(isAngleRad) {
x=Double.parseDouble(xval.getText());
str="cos("+x+")=";
}else {
x=Double.parseDouble(xval.getText())/180*3.1415926;
//***************************Found*********************
str="cos("+xval.getText() +"*3.14159/180)=";
};
y=Math.cos(x);
result.append(str+y+'\n');
}else if(e.getSource()== angleUnitBtn){
if(isAngleRad)
angleUnitBtn.setText("设成弧度");
else
//***************************Found*********************
angleUnitBtn.setText( "设成角度");
//***************************Found*********************
isAngleRad= !isAngleRad ;
}
}
public static void main(String[] args){
new Java_3();
}
}
3.52
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Java_3 {
public static void main(String[] args) {
JFrame f = new JFrame("计算");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(new MyPanel());
f.setSize(300, 130);
//**********Found**********
f.setVisible(true);
}
}
class MyPanel extends JPanel {
JTextField t1, t2;
JButton b1, b2;
JLabel l1, l3;
MyPanel() {
setLayout(new BorderLayout());
t1 = new JTextField(5);
t2 = new JTextField(5);
l1 = new JLabel("op");
JLabel l2 = new JLabel("=");
l3 = new JLabel("00");
JPanel p1 = new JPanel();
p1.add(t1);
p1.add(l1);
p1.add(t2);
p1.add(l2);
p1.add(l3);
JPanel p2 = new JPanel();
b1 = new JButton("加");
b2 = new JButton("减");
p2.add(b1);
p2.add(b2);
add(p1, BorderLayout.CENTER);
//**********Found**********
add(p2, BorderLayout.SOUTH);
//**********Found**********
b1.addActionListener(new BListener() );
//**********Found**********
b2.addActionListener(new BListener() );
}
//**********Found**********
private class BListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
int a = 0, b = 0;
try {
//**********Found**********
a = Integer.parseInt(t1.getText() );
//**********Found**********
b = Integer.parseInt(t2.getText() );
} catch (Exception ee) {
}
//**********Found**********
if (e.getSource() == b1) {
l1.setText("+");
l3.setText(String.valueOf(a+b));
} else {
l1.setText("-");
l3.setText(String.valueOf(a-b));
}
}
}
}
3.53
import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Java_3 {
public static void main(String[] args) {
JFrame jFrame = new JFrame("测试窗口");
jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jFrame.setSize(300,120);
//**********Found**********
JPanel jPanel = new JPanel();
jFrame.add(jPanel);
jPanelDefault(jPanel);
//**********Found**********
jFrame.setVisible(true);
}
static JLabel jl = new JLabel("请输入：");
static JTextField jtf = new JTextField();
public static void jPanelDefault(JPanel jPanel){
jPanel.setLayout(null);
jl.setBounds(30, 10, 80, 20);
jPanel.add(jl);
jtf.setColumns(20);
jtf.setBounds(120, 10, 100,20);
jPanel.add(jtf);
JButton jb0 = new JButton("确认");
jb0.setBounds(60, 40, 60, 20);
//**********Found**********
jb0.addActionListener(new ActionListener() {
//**********Found**********
public void actionPerformed(ActionEvent e) {
//**********Found**********
JOptionPane.showMessageDialog(null, "保存成功：" + jtf.getText());
}
});
jPanel.add(jb0);
JButton jb1 = new JButton("取消");
jb1.setBounds(160, 40, 60, 20);
jb1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
//**********Found**********
System.exit(0);
}
});
jPanel.add(jb1);
}
}
3.54
import java.io.*;
import java.awt.*;
import java.awt.event.* ;
import javax.swing.*;
public class Java_3 implements ActionListener {
JTextArea ta1,ta2,ta3;
JFrame f ;
JLabel label1,label2;
JButton bs,br;
JPanel jp1,jp2;
String ss;
public static void main(String [ ]args){
Java_3 t = new Java_3();
t.go();
}
void go(){
f = new JFrame("Data Input and Output");
f.setLayout(new GridLayout(2,1));
label1 = new JLabel("姓名： ");
ta1 = new JTextArea(1,10);
bs = new JButton("保存到文件");
label2 = new JLabel(" 电话： ");
ta2 = new JTextArea(1,15);
ta3 = new JTextArea(1,25);
br = new JButton("读取并确认");
jp1 = new JPanel();
jp2 = new JPanel();
jp1.add(label1);
jp1.add(ta1);
jp1.add(label2);
jp1.add(ta2);
jp1.add(bs);
//**********Found**********
f.add(jp1);
jp2.add(ta3);
jp2.add(br);
f.add(jp2);
//**********Found**********
bs.addActionListener(this);
//**********Found**********
br.addActionListener( new ReadFile());
f.pack( );
f.setLocationRelativeTo(null);
f.setVisible(true) ;
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void actionPerformed(ActionEvent event){
try{
//**********Found**********
FileWriter fw = new FileWriter(out.txt);
BufferedWriter bf = new BufferedWriter(fw);
ss=ta1.getText();
bf.write(ss,0,ss.length());
bf.newLine();
ss=ta2.getText();
bf.write(ss,0,ss.length());
bf.close();
} catch( Exception e){
}
}
class ReadFile implements ActionListener{
public void actionPerformed(ActionEvent event){
int i=0;
char c;
char[] a1= new char[50];
String str ;
try{
BufferedReader in = new BufferedReader( new FileReader("out.txt"));
//**********Found**********
ss=in.readLine();
str = " 姓名：" +ss;
str = str+" 电话："+in.readLine();
in.close();
//**********Found**********
ta3.setText(str);
} catch( Exception e){ }
}
}
}
3.55
//程序的功能是求以命令行参数指定的整数的阶乘。
public class Java_3{
public static void main(String[] args){
String num;
if(args.length > 0)
//*********Found********
num = args[0];
else
num = "5";
//*********Found********
int input = Integer.parseInt(num);
double result = factorial(input);
System.out.println(input+ " 的阶乘是 "+ result);
}
public static double factorial(int x){
if( x < 0 )
return 0.0;
double fact = 1.0;
while(x > 1){
//*********Found********
fact =fact *x;
//*********Found********
x = x-1;
}
return fact;
}
}
3.56
import java.io.*;
import java.awt.*;
import java.awt.event.* ;
import javax.swing.*;
public class Java_3 implements ActionListener {
JTextArea ta1,ta2;
JFrame f ;
JLabel label1;
JButton bs;
public static void main(String args[ ]){
Java_3 t = new Java_3();
//**********Found**********
t.go() ;
}
void go(){
f = new JFrame("Simple Editing");
f.setSize( 20, 200);
f.setLayout(new GridLayout(2,3,5,5));
label1 = new JLabel("编辑文本：");
ta1 = new JTextArea(2,20);
bs = new JButton("保存并再次读取：");
ta2 = new JTextArea(2,20);
f.add(label1);
f.add(ta1);
f.add(bs);
f.add(ta2);
//**********Found**********
bs.addActionListener(this);
f.setSize(400,400);
f.pack( );
f.setVisible(true) ;
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void actionPerformed(ActionEvent event){
String input;
//**********Found**********
try{
PrintWriter out = new PrintWriter("in.txt");
out.println(ta1.getText());
out.close();
//**********Found**********
BufferedReader in = new BufferedReader(new FileReader("in.txt"));
input = in.readLine();
//**********Found**********
ta2.setText(input);
in.close();
//**********Found**********
} catch( Exception e){
}
}
}
3.57
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
//**********Found**********
public class Java_3 extends JFrame implements FocusListener{
//**********Found**********
private JTextField tUser, tID, tPW;
public Java_3() {
JLabel User = new JLabel("姓名", JLabel.CENTER);
JLabel ID = new JLabel("学号", JLabel.CENTER);
JLabel PW = new JLabel("电子邮箱", JLabel.CENTER);
tUser = new JTextField(10);
tID = new JTextField(20);
tPW = new JTextField(25);
User.setFont(new Font("Dialog", Font.PLAIN, 20));
ID.setFont(new Font("Dialog", Font.PLAIN, 20));
PW.setFont(new Font("Dialog", Font.PLAIN, 20));
//**********Found**********
setLayout(new GridLayout(3, 2));
add(User);
add(tUser);
add(ID);
add(tID);
add(PW);
add(tPW);
//**********Found**********
tUser.addFocusListener(this);
tID.addFocusListener(this);
tPW.addFocusListener(this);
}
//**********Found**********
public void focusGained(FocusEvent e) {
JComponent component = (JComponent)e.getSource();
if(component==tUser) {
tUser.setText("姓名文本框获得了焦点");
tUser.setBackground(Color.white);
}else if(component==tID) {
tID.setText("学号文本框获得了焦点");
tID.setBackground(Color.white);
}else if(component==tPW) {
tPW.setText("电子邮箱文本框获得了焦点");
tPW.setBackground(Color.white);
}
}
public void focusLost(FocusEvent e) {
JComponent component = (JComponent)e.getSource();
if(component==tUser) {
tUser.setText("");
tUser.setBackground(Color.RED);
}else if(component==tID) {
tID.setText("");
tID.setBackground(Color.RED);
}else if(component==tPW) {
tPW.setText("");
tPW.setBackground(Color.RED);
}
}
public static void main(String[] args) {
Java_3 ft = new Java_3();
ft.pack();
ft.setLocationRelativeTo(null);
ft.setResizable(false);
//**********Found**********
ft.setVisible(true);
ft.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
标签：Java,String,int,操作题,void,Found,new,最新版,public
From： https://blog.csdn.net/yueqingll/article/details/141940090