Question

我把这个try / catch包裹在do / while循环中，因为在try / catch抛出错误消息之后，我希望它循环回到顶部。我尝试do / while，while，我尝试将while循环放在我的代码中的不同位置，但没有任何作用。程序运行正常，直到抛出异常，然后进入无限循环。之后显示错误消息，我只想让它循环回到顶部。

public static void main(String[] args) {

    Scanner input = new Scanner( System.in );

    Integer userInput;
  do {
   try{ 
    System.out.print("Enter a number? \n");
    userInput = input.nextInt();

      if ( userInput == 1 )
         Animal1.displayMessage ();//Display the total
      if( userInput == 2 )
         Animal2.displayMessage ();//Display the total

      }
       catch (Exception e) {
        System.out.println(" That's not right ");
        break;

      }
      } while (true);
      }

}

这是显示错误消息后的作用。

    Enter a number? 
 That's not right 
Enter a number? 
 That's not right 
Enter a number? 
 That's not right 
Enter a number? 
 That's not right 
Enter a number? 
 That's not right 
Enter a number? 
 That's not right 
Enter a number? 
 That's not right 
Enter a number? 
 That's not right 
Enter a number? 
Enter a number?

如果我不停止它，它就会继续前进。

Answer 1

您可以尝试以下解决方法：

public static void main(String[] args) {

    Scanner input = new Scanner( System.in );

    Integer userInput;
  do {
   try{ 
    System.out.print("Enter a number? \n");
    userInput = input.nextInt();

      if ( userInput == 1 )
         Animal1.displayMessage ();//Display the total
      if( userInput == 2 )
         Animal2.displayMessage ();//Display the total

      }
       catch (Exception e) {
        System.out.println(" That's not right ");
        input.next();

      }
      } while (true);
      }

}

或者如果你想避免试试：

public static void main(String[] args) {

        Scanner input = new Scanner(System.in);

        Integer userInput = 0;
        do {
            System.out.print("Enter a number? \n");
            if (input.hasNextInt())
                userInput = input.nextInt();
            else {
                System.out.println(" That's not right ");
                input.next();
            }
            if (userInput == 1)
                Animal1.displayMessage ();//Display the total
            ;// Display the total
            if (userInput == 2)
                Animal2.displayMessage ();//Display the total

        } while (true);
    }

Answer 2

您可以提供3个选项 - 退出一个选项

System.out.print("Enter a number? \n 1 to display Animal1 total\n2 to display Animal2 total\n 3 to exit");

在while循环中，您可以添加

if ( userInput == 3) break;

Answer 3

您需要将try / catch语句放在循环之外。

如何在Java中无限循环停止循环？

3 个答案: