Question

I have the following code which I’m using to get the user to input an integer, check to make sure the input is valid, and if not, ask for input again. When the code is run, everything works fine until some invalid input is given, at which point the code loops without pausing to ask for input again until a stack overflow occurs, and I have no idea why. The code:

//Create the scanner object
private static Scanner in = new Scanner(System.in);

//Function to get input in integer form, complete with exception handling
//A value of -1 means the user is done inputing
public static int getInt()
{
    int num;

    //Begin try block
    try
    {
        //Get the user to input an integer
        num = in.nextInt();

        //Make sure the integer is positive. Throw an exception otherwise
        if (num < -1)
            throw new InputMismatchException();
    }

    //If an exception occurred during the inputting process, recursively call this function
    catch (InputMismatchException e)
    {
        System.out.println("Error: Input must be a positive integer, or -1.");
        System.out.print("Enter a score: ");
        num = getInt();
    }

    //Return the inputed number
    return num;
}

Answer 1

When a scanner throws an InputMismatchException, the scanner will not
pass the token that caused the exception, so that it may be retrieved
or skipped via some other method

So sayeth the javadoc, i.e. the string that is not a number is not removed from the input automatically. Call in.next() manually to discard it.