IntegerInput.java

import java.util.Scanner;
import java.util.InputMismatchException;

public class IntegerInput {

    /**
    *   Program:    IntegerInput.java
    *   Purpose:    Validating user input
    *   Creator:    Chris Clarke
    *   Created:    04.03.2014
    */

    private static final int MIN = 1;
    private static final int MAX = 21;

    public static void main(String[] args) {

        // create scanner for keyboard input
        Scanner keybd = new Scanner(System.in);
        int n;

        // start do..while loop
        do {
            // prompt user
            System.out.print("Enter integer number between "+MIN+" and "+MAX+": ");

            try {
                // get an integer
                n = keybd.nextInt();
            } catch (InputMismatchException e) {
                // display error message
                System.out.println("That\'s not an integer!");
                // quit program
                return;
            } // end try/catch

            if (n<MIN) {
                System.out.println("Number too low! Must be "+MIN+" or above.");
            } else if (n>MAX) {
                System.out.println("Number too high! Must be "+MAX+" or below.");
            } // end if
        // ...while outside range
        } while (n<MIN || n>MAX);

        // confirm number entered by user
        System.out.println("Thank you.  You entered "+n+".");

    } // end main()

} // end class IntegerInput