Java如何在switch语句下打断while循环？

我有一个function来实现一个简单的testing应用程序，下面是我目前的代码：

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"); } } 

现在我想要做的是，当按下0时，意味着用户想要退出testing，然后打破while loop并打印Test is done ，但它不工作，我知道原因可能当"break"断开switch ，我怎么能让它打破while loop呢？

Answer 1

你可以label你的while循环，并break labeled loop ，应该是这样的：

 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单词，例如"loop1" 。

Answer 2

你需要一个布尔variables例如shouldBreak 。

  boolean shouldBreak = false; switch(typing){ case 0: shouldBreak = true; 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"); } if (shouldBreak) break; 

Answer 3

把一个function放在里面，当你按0而不是打破就return 。 例如 ：

  import java.util.*; public class Test{ private static int typing; public static void main(String argv[]){ Scanner sc = new Scanner(System.in); func(sc); System.out.println("Test is done"); } } public static void func(Scanner sc) { System.out.println("Testing starts"); while(sc.hasNextInt()){ typing = sc.nextInt(); switch(typing){ case 0: return; //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"); } } } }