Java Program to check Armstrong Number

// Java program to determine whether the
// Number is Armstrong number or not
public class Armstrong {
    // Function to calculate x raised to the
    //   power y
    int power(int x, long y)
    {
        if (y == 0)
            return 1;
        if (y % 2 == 0)
            return power(x, y / 2) * power(x, y / 2);
        return x * power(x, y / 2) * power(x, y / 2);
    }

    // Function to calculate order of the number 
    int order(int x)
    {
        int n = 0;
        while (x != 0) {
            n++;
            x = x / 10;
        }
        return n;
    }

    // Function to check whether the given number is
    // Armstrong number or not
    boolean isArmstrong(int x)
    {
        // Calling order function
        int n = order(x);
        int temp = x, sum = 0;
        while (temp != 0) {
            int r = temp % 10;
            sum = sum + power(r, n);
            temp = temp / 10;
        }

        // If satisfies Armstrong condition
        return (sum == x);
    }

    // Driver Program
    public static void main(String[] args)
    {
        Armstrong ob = new Armstrong();
        int x = 153;
        System.out.println(x + " : " + ob.isArmstrong(x));
        x = 1253;
        System.out.println(x + " : " + ob.isArmstrong(x));
    }
}

// Java Program to implement Recursive
// Method for Checking Armstrong Number
import java.io.*;

// Armstrong Class
class Armstrong {
    // Function to Calculate power
    // Of a Number
    int power(int x, long y)
    {
        if (y == 0)
            return 1;
        if (y % 2 == 0)
            return power(x, y / 2) * power(x, y / 2);
        return x * power(x, y / 2) * power(x, y / 2);
    }

    // Function to Perform all the
    // Calculation
    // (Recursive Method)
    int cal(int x, int dig)
    {
        if (x == 0)
            return 0;

        int num = x % 10;

        return cal(x / 10, dig) + power(num, dig);
    }

    // Functions to Calculate Number
    // of Digits in a Number
    int cal_digits(int x)
    {
        int dig = 0;

        while (x != 0) {
            dig++;
            x = x / 10;
        }

        return dig;
    }

    // Function to check if a
    // Number is Armstrong or Not
    public boolean isArmstrong(int x)
    {
        int dig = cal_digits(x);

        if (dig <= 1)
            return true;

        int res = cal(x, dig);

        return res == x;
    }
}

// Driver Class
class GFG {
    // main function
    public static void main(String[] args)
    {
        Armstrong ob = new Armstrong();
        
          int x = 153;
        System.out.println(x + " : " + ob.isArmstrong(x));
        
          x = 1253;
        System.out.println(x + " : " + ob.isArmstrong(x));
    }
}