Java 如何在 switch 语句下中断 while 循环? [英] Java How can I break a while loop under a switch statement?

问题描述

我有一个作业来实现一个简单的测试应用程序，以下是我当前的代码:

I have a homework to implement a simple testing application, below is my current code:

import java.util.*;

public class Test{

private static int typing;

public static void main(String argv[]){
    Scanner sc = new Scanner(System.in);
    System.out.println("Testing starts");
    while(sc.hasNextInt()){
        typing = sc.nextInt();
        switch(typing){
            case 0:
              break; //Here I want to break the while loop
            case 1:
              System.out.println("You choosed 1");
              break;
            case 2:
              System.out.println("You choosed 2");
              break;
            default:
              System.out.println("No such choice");
        }
    }
      System.out.println("Test is done");
    }
}

我现在要做的是，当按下0时，表示用户想退出测试，然后我打破while循环并打印测试完成，但它不那样工作，我知道原因可能是"break"打破了switch，怎么能我让它打破 while 循环 代替?

What I want to do now is that when 0 is pressed, it means that the user wants to quit the test, then I break the while loop and print Test is done, but it doesn't work like that, I know the reason might be that the "break" breaks the switch, how can I let it break the while loop instead?

推荐答案

你可以label你的while循环，以及breaklabeled loop，应该是这样的:

You can label your while loop, and break the labeled loop, which should be like this:

loop: while(sc.hasNextInt()){
    typing = sc.nextInt();
    switch(typing){
        case 0:
          break loop; 
        case 1:
          System.out.println("You choosed 1");
          break;
        case 2:
          System.out.println("You choosed 2");
          break;
        default:
          System.out.println("No such choice");
    }
}

label 可以是任何你想要的词，例如 "loop1".

And the label can be any word you want, for example "loop1".

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