使用InputMismatchException try/catch塊

Question

我想捕獲任何不是Int的輸入，並提示輸入有效的輸入3次。 3次後，該計劃將繼續並要求另一個評級。我似乎無法重複try/catch塊，甚至無法捕獲InputMismatchException。有什麼建議麼？

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

你既可以做一個循環：

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); 

個人而言，我更喜歡第一種方法。

我想這個代碼，並運行，沒有任何例外：

公共類主要{

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); 

} 

}