How to check Armstrong number java program

In previous post How to reverse a number in Java we learnt how to reverse a positive or negative numbers in java
In this post we will write a java program to check Whether number is armstrong or not.

What is Armstrong number?

An n-digit number that is the sum of the th powers of its digits is called an Armstrong number.

In another words we can define Armstrong number as below:

We can define an Armstrong number is a number that is equal to the sum of the digits in a number raised to the power of number of digits in the number.

package com.kkjavatutorials.client;

import java.util.Scanner;
/**
 * @author KK JavaTutorials
 *  Java program to check Armstrong number
 */
public class ClientTest {

	public static void main(String[] args) {

		try (Scanner scanner = new Scanner(System.in)) {
			// Take a number from keyboard using Scanner
			System.out.println("Enter Number:");
			int number = scanner.nextInt();
			boolean isArmstrong = isArmstrongNumber(number);
			if (isArmstrong) {
				System.out.println(number + "  is an Armstrong number");
			} else {
				System.out.println(number + " is not an Armstrong number");
			}
		} catch (Exception e) {
			System.out.println("Please Enter valid number..");
			e.printStackTrace();
		}
	}

	private static boolean isArmstrongNumber(int number) {
		//convert number to String
		String numberToString = String.valueOf(number);
		int lengthOfNumber = numberToString.length();
		int numberCopy = number;
		int sum = 0;
		while (numberCopy != 0) {
			int remainder = numberCopy % 10;
			//Here we use Math class pow function to get digit raised to the power total number of digits
			sum = sum + (int) Math.pow(remainder, lengthOfNumber);
			numberCopy = numberCopy / 10;
		}
		return (sum == number) ? true : false;
	}
}

package com.kkjavatutorials.client;

import java.util.Scanner;

/**

* @author KK JavaTutorials

* Java program to check Armstrong number

public class ClientTest {

public static void main(String[] args) {

try (Scanner scanner = new Scanner(System.in)) {

// Take a number from keyboard using Scanner

System.out.println("Enter Number:");

int number = scanner.nextInt();

boolean isArmstrong = isArmstrongNumber(number);

if (isArmstrong) {

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

} else {

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

}

} catch (Exception e) {

System.out.println("Please Enter valid number..");

e.printStackTrace();

}

private static boolean isArmstrongNumber(int number) {

//convert number to String

String numberToString = String.valueOf(number);

int lengthOfNumber = numberToString.length();

int numberCopy = number;

int sum = 0;

while (numberCopy != 0) {

int remainder = numberCopy % 10;

//Here we use Math class pow function to get digit raised to the power total number of digits

sum = sum + (int) Math.pow(remainder, lengthOfNumber);

numberCopy = numberCopy / 10;

}

return (sum == number) ? true : false;

}

I have tested above program for few inputs as below. You may check for other input as well .

Enter Number:
153
153  is an Armstrong number

Enter Number:
453
453 is not an Armstrong number

Enter Number:
371
371  is an Armstrong number

Enter Number:
9474
9474  is an Armstrong number

Enter Number:
1
1  is an Armstrong number

Enter Number:

153

153 is an Armstrong number

Enter Number:

453

453 is not an Armstrong number

Enter Number:

371

371 is an Armstrong number

Enter Number:

9474

9474 is an Armstrong number

Enter Number:

1 is an Armstrong number

That’s all about this topic How to check Armstrong number java program
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