Check Scanner number input boundary in Java

In many cases if you want to create an interactive command line interface, you need to check if a number entered by the user is valid and – if it isn’t – you want the user to re-input it.

Here’s a simple static method to check if a number typed by a user is within a given boundary:

 * Lets the user input an integer value until it satisfies the given
 * conditions
 * @param msg The prompt to ask the user for the value.
 * @param lower The lower boundary, inclusive
 * @param upper The upper boundary, inclusive
private static int guardedInput(String msg, int lower, int upper) {
    Scanner scanner = new Scanner(;
    while (true) {
        int val = -1;
        try {
        val = scanner.nextInt();
        } catch (InputMismatchException ex) {
        System.out.println("Illegal value: Please type a number!");
        if (val < lower) {
        System.out.println("Illegal value: Must be greater than " + (lower - 1));
        } else if (val > upper) {
        System.out.println("Illegal value: Must be smaller than " + (upper + 1));
        } else {
        return val;