使用InputMismatchException try/catch块

Question

我想捕获任何不是Int的输入，并提示输入有效的输入3次。 3次后，该计划将继续并要求另一个评级。我似乎无法重复try/catch块，甚至无法捕获InputMismatchException。有什么建议么？

do { 
    //prompt for rating 
     try { 
     System.out.println("Enter a rating between 0-4 for the Movie of the Week (Enter -1 to stop/exit): "); 
     //capture 
      rating = response.nextInt(); 
     } catch (InputMismatchException err) { 
      System.out.println("Invalid input. Please enter a rating 0-4 or enter -1 to exit: "); 
      rating = response.nextInt(); 
     } //end catch 
    } while (rating >= 0); 

Answer 1

你既可以做一个循环：

int count = 0; 
do { 
    //prompt for rating 
     try { 
     System.out.println("Enter a rating between 0-4 for the Movie of the Week (Enter -1 to stop/exit): "); 
     //capture 
      rating = response.nextInt(); 
     } catch (InputMismatchException err) { 
      System.out.println("Invalid input. Please enter a rating 0-4 or enter -1 to exit: "); 
      count++; 
     } //end catch 
    } while (rating >= 0 && count < 3); 

或者使用嵌套的try/catch：

do { 
    //prompt for rating 
     try { 
     System.out.println("Enter a rating between 0-4 for the Movie of the Week (Enter -1 to stop/exit): "); 
     //capture 
      rating = response.nextInt(); 
     } catch (InputMismatchException err) { 
      System.out.println("Invalid input. Please enter a rating 0-4 or enter -1 to exit: "); 
      try { 
     System.out.println("Enter a rating between 0-4 for the Movie of the Week (Enter -1 to stop/exit): "); 
     //capture 
      rating = response.nextInt(); 
     } catch (InputMismatchException err) { 
      System.out.println("Invalid input. Please enter a rating 0-4 or enter -1 to exit: "); 
      rating = response.nextInt(); 
     } //end catch 
     } //end catch 
    } while (rating >= 0); 

个人而言，我更喜欢第一种方法。

我想这个代码，并运行，没有任何例外：

公共类主要{

public static void main(String[] args) throws IOException { 
    int count = 0; 
    int rating = 0; 
    do { 
     Scanner response = new Scanner(System.in); 
     //prompt for rating 
      try { 
      System.out.println("Enter a rating between 0-4 for the Movie of the Week (Enter -1 to stop/exit): "); 
      //capture 
       rating = response.nextInt(); 

      } catch (InputMismatchException err) { 
       System.out.println("Invalid input. Please enter a rating 0-4 or enter -1 to exit: "); 
      } finally { 
       count++; 
       System.out.println("Rating-->" + rating); 
      } 
     } while (rating >= 0 && count < 3); 

} 

}