PTA Java 函数题
先记录，有时间再整理。
是否偶数
public static boolean isOdd(int data){
return data%2==0?true:false;
}
根据派生类写出基类（Java）
public People() {
}
public People(String id,String name) {
this.id=id;
this.name=name;
}
public void setId(String id){
this.id=id;
}
public String getId(){
return this.id;
}
public void setName(String name) {
this.name=name;
}
public String getName() {
return this.name;
}
public void say() {
// TODO Auto-generated method stub
System.out.println("I'm a person! My name is " + this.name + ".");
}
使用继承设计：教师类。
class Teacher extends Person{//继承
String professional;//定义专业名
Teacher(String name, int age, String professional) {
super(name, age);
this.professional=professional;
}
void work(){
System.out.println(professional);
System.out.println("教师的工作是教学。");
}
}
设计一个Duck类及其子类
class Duck {
public void display() {
// TODO Auto-generated method stub
}
public void quack() {
System.out.println("我会呱呱呱");
}
public void swim() {
System.out.println("我会游泳");
}
public void fly() {
System.out.println("我会飞");
}
}
//RedheadDuck类的定义
class RedheadDuck extends Duck {
public void display() {
System.out.println("我是一只红头鸭");
}
}
//MallardDuck类的定义
class MallardDuck extends Duck {
public void display() {
System.out.println("我是一只绿头鸭");
}
}
jmu-Java-03面向对象基础-覆盖与toString
public String toString() {
return super.toString()+"-"+company.toString()+"-"+salary;
}
重写父类方法equals
public boolean equals(Object obj) {
boolean boo=false;
if(obj instanceof Student) {
Student s=(Student) obj;
if(s.id==this.id)
{
boo=true;
}
}
return boo;
}
从抽象类shape类扩展出一个圆形类Circle
class Circle extends shape{
private double radius;
public Circle(double radius){
this.radius =radius;
}
public double getArea(){
return Math.PI *radius*radius;
}
public double getPerimeter( ) {
return 2*Math.PI*radius;
}
}
创建一个直角三角形类实现IShape接口
class RTriangle implements IShape{
double a,b;
public RTriangle(double a, double b) {
super();
this.a = a;
this.b = b;
}
public double getArea() {
return 0.5*a*b;
}
public double getPerimeter() {
return a+b+Math.sqrt(a*a+b*b);
}
}
jmu-Java-06异常-finally
System.out.println("resource open success");
}catch(Exception e){
System.out.println(e);
}
try{
resource.close();
System.out.println("resource release success");
}catch(RuntimeException e){
System.out.println(e);
}
异常-多种类型异常的捕获
catch(Exception e){
if (choice.equals("number"))
System.out.println ("number format exception");
if (choice.equals("illegal"))
System.out.println ("illegal argument exception");
if (choice.equals("except"))
System.out.println ("other exception");
System.out.println (e);
}
求圆面积自定义异常类
class Circle{
double r;
Circle(double r) {
this.r = r;
}
public double area() throws CircleException{
if(r<0)
{//判断异常是否会产生
CircleException e = new CircleException(r);//在创建对象时将半径赋值给CircleException对象
throw e;//抛出异常
}
return 3.14rr;
}
}
class CircleException extends Exception {
double r;
CircleException(double r){//有参数的构造方法
this.r = r;
}
public void print () {//被调用的print语句
System.out.println("圆半径为"+r+"不合理");
}
}
jmu-Java-07多线程-Thread
class MyThread extends Thread{
int i;
public MyThread(int i){
this.i=i;
}
public void run () {
for(int r=0;r<i;r++) {
System.out.println(r);
}
System.out.println(Thread.currentThread().getName()+" "+isAlive());
}
}
jmu-Java-07多线程-PrintTask
class PrintTask implements Runnable
{
private int n;
public PrintTask(int n)
{
this.n=n;
}
public void run()
{
for(int i=0;i<n;i++)
{
System.out.println(i);
}
System.out.println(Thread.currentThread().getName());
}
}
数组工具类的设计
class MyArrays
{
public static void printArray(int a[])
{
for(int i=0;i<a.length;i++)
{
if(i==a.length-1)
{
System.out.println(a[i]);
}
else
System.out.print(a[i]+",");
}
}
public static void sortArray(int a[])
{
for(int i=0;i<a.length-1;i++)
{
for(int j=0;j<a.length-1-i;j++)
{
int temp=0;
if(a[j]>a[j+1])
{
temp=a[j];
a[j]=a[j+1];
a[j+1]=temp;
}
}
}
}
public static int sumOfArray(int a[])
{
int sum=0;
for(int i=0;i<a.length;i++)
{
sum=sum+a[i];
}
return sum;
}
}