Check for Armstrong number in java

public class ArmstrongNumber {
    public static void main(String[] args) {
        int num = 153, originalNum, sum = 0, n = 0;
        originalNum = num;
        n = String.valueOf(num).length();
        while (num != 0) {
            int digit = num % 10;
            sum += Math.pow(digit, n);
            num /= 10;
        }
        System.out.println("Armstrong? " + (sum == originalNum));
    }
}