Using InputMismatchException try/catch block

问题

I want to catch any input that is not an Int and prompt for a valid input 3 times. After 3 times, the program will move on and ask for another rating. I can't seem to have the try/catch block repeat or even catch the InputMismatchException. Any suggestions?

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);

回答1:

You could either do it in a loop:

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);

Or use a nested 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);

Personally I would prefer the first method.

I tried this code and it ran without any Exception:

public class Main {

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);

}

}

来源：https://stackoverflow.com/questions/29813230/using-inputmismatchexception-try-catch-block

标签

java

try-catch