## Scanner对象
![image-20221220230006357](C:\Users\biao\AppData\Roaming\Typora\typora-user-images\image-20221220230006357.png)
![image-20221220232935206](C:\Users\biao\AppData\Roaming\Typora\typora-user-images\image-20221220232935206.png)
```
凡是属于IO流的类如果不关闭会一直占用资源,要养成好习惯用完就关掉
```
package com.fang.scanner;
import java.util.Scanner;
public class Demo01 {
public static void main(String[] args) {
//创建一个扫描器对象,用于接收键盘数据
Scanner scanner = new Scanner(System.in);
System.out.println("使用next方式接收:");
//判断用户有没有输入字符串
if (scanner.hasNext()){
//使用next方式接收
String str = scanner.next();//程序会等待用户输入完毕
System.out.println("输出的内容为:"+str);
}
//凡是属于IO流的类如果不关闭会一直占用资源,要养成好习惯用完就关掉
scanner.close();
}
}
package com.fang.scanner;
import java.util.Scanner;
public class Demo02 {
public static void main(String[] args) {
// 从键盘接收数据
Scanner scanner = new Scanner(System.in);
System.out.println("使用nextLine方式接收:");
//判断是否还有输入
if (scanner.hasNextLine()){
String str = scanner.nextLine();
System.out.println("输出的内容为:"+str);
}
scanner.close();
}
}
package com.fang.scanner;
import java.util.Scanner;
public class Demo03 {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("请输入数据:");
String str = scanner.nextLine();
System.out.println("输入的内容为:"+str);
scanner.close();
}
}
package com.fang.scanner;
import java.util.Scanner;
public class Demo04 {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
//从键盘接收数据
int i = 0;
float f = 0.0f;
System.out.println("请输入整数:");
//如果。。。那么
if (scanner.hasNextInt()){
i = scanner.nextInt();
System.out.println("整数数据:"+i);
}else{
System.out.println("输入的不是整数数据!");
}
System.out.println("请输入小数:");
//如果。。。那么
if (scanner.hasNextFloat()){
f = scanner.nextFloat();
System.out.println("输入的小数为:"+f);
}else {
System.out.println("输入的不是小数数据!");
}
scanner.close();
}
}
package com.fang.scanner;
import java.util.Scanner;
public class Demo05 {
public static void main(String[] args) {
//我们可以输入多个数字,并求其总和与平均数,每输入一个数字用回车确认,通过输入非数字来结束输入并输出执行结果:
Scanner scanner = new Scanner(System.in);
//和
double sum = 0;
//计算输入了多少个数字
int m = 0;
//通过循环判断是否还有输入,并在里面对每一次进行求和和统计
while (scanner.hasNextDouble()){
double v = scanner.nextDouble();
m = m + 1;//m++
sum = sum + v;
System.out.println("你输入了第"+m+"个数据,然后当前结果sum="+sum);
}
System.out.println(m + "个数的和为" + sum);
System.out.println(m + "个数的平均值为" + (sum/m));
scanner.close();
}
}
标签:scanner,Scanner,System,day11,println,输入,out From: https://www.cnblogs.com/biao3/p/16996573.html