Given Number Is Armstrong Number or Not Java Program

Program:

Write a program to find the given number is Armstrong number or not?

Description:

Armstrong numbers are the sum of their own digits to the power of
the number of digits. It is also known as narcissistic numbers.

Code:

package com.java2novice.algos;

public class MyArmstrongNumber {

    public boolean isArmstrongNumber(int number){
        
        int tmp = number;
        int noOfDigits = String.valueOf(number).length();
        int sum = 0;
        int div = 0;
        while(tmp > 0)
        {
            div = tmp % 10;
            int temp = 1;
            for(int i=0;i<noOfDigits;i++){
                temp *= div;
            }
            sum += temp;
            tmp = tmp/10;
        }
        if(number == sum) {
            return true;
        } else {
            return false;
        }
    }
    
    public static void main(String a[]){
        MyArmstrongNumber man = new MyArmstrongNumber();
        System.out.println("Is 371 Armstrong number? "+man.isArmstrongNumber(371));
        System.out.println("Is 523 Armstrong number? "+man.isArmstrongNumber(523));
        System.out.println("Is 153 Armstrong number? "+man.isArmstrongNumber(153));
    }
}

Output:

Is 371 Armstrong number? true
Is 523 Armstrong number? false
Is 153 Armstrong number? true

Here's a simple Java program to check if a given number is an Armstrong number:

import java.util.Scanner;

public class ArmstrongNumber {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);

        

        System.out.print("Enter a number: ");

        int number = scanner.nextInt();

        

        if (isArmstrong(number)) {

            System.out.println(number + " is an Armstrong number.");

        } else {

            System.out.println(number + " is not an Armstrong number.");

        }

        

        scanner.close();

    }

    public static boolean isArmstrong(int number) {

        int sum = 0;

        int originalNumber = number;

        int digits = String.valueOf(number).length(); // Calculate number of digits

        

        while (number > 0) {

            int digit = number % 10; // Get last digit

            sum += Math.pow(digit, digits); // Raise to the power of the number of digits

            number /= 10; // Remove last digit

        }

        

        return sum == originalNumber; // Check if the sum equals the original number

    }

}

Explanation:

1. Input: The program takes an integer input from the user.
2. Armstrong Check:
   • It calculates the number of digits in the number.
   • It extracts each digit, raises it to the power of the number of digits, and sums these values.
3. Output: Finally, it compares the sum to the original number and prints whether it is an Armstrong number.

Example:

• For input 153, the output will be 153 is an Armstrong number. because $1^3 + 5^3 + 3^3 = 153$.
• For input 123, the output will be 123 is not an Armstrong number. because $1^3 + 2^3 + 3^3 \neq 123$.