Java Program to Check Armstrong Number

Here we will write a java program that checks whether the given number is Armstrong number or not. We will see the two variation of the same program. In the first program we will assign the number in the program itself and in second program user would input the number and the program will check whether the input number is Armstrong or not.

Before we go through the program, lets see what is an Armstrong number. A number is called Armstrong number if the following equation holds true for that number:

xy..z = xn + yn+.....+ zn

where n denotes the number of digits in the number

For example this is a 3 digit Armstrong number

370 = 33 + 73 + o3
         = 27 + 343 + 0
         = 370

Let’s write this in a program:
To understand this Program you should have the knowledge of following Java Programming topics:

1. Java while loop
2. Java if..else-if

Example 1: Program to check whether the given number is Armstrong number

public class JavaExample {

    public static void main(String[] args) {

        int num = 370, number, temp, total = 0;

        number = num;
        while (number != 0)
        {
            temp = number % 10;
            total = total + temp*temp*temp;
            number /= 10;
        }

        if(total == num)
            System.out.println(num + " is an Armstrong number");
        else
            System.out.println(num + " is not an Armstrong number");
    }
}

Output:

370 is an Armstrong number

In the above program we have used while loop, However you can also use for loop. To use for loop replace the while loop part of the program with this code:
for( ;number!=0;number /= 10){
    temp = number % 10;
    total = total + temp*temp*temp;
}
Example 2: Program to check whether the input number is Armstrong or not
import java.util.Scanner;
public class JavaExample {

    public static void main(String[] args) {

        int num, number, temp, total = 0;
        System.out.println("Ënter 3 Digit Number");
        Scanner scanner = new Scanner(System.in);
        num = scanner.nextInt();
        scanner.close();
        number = num;

        for( ;number!=0;number /= 10)
        {
            temp = number % 10;
            total = total + temp*temp*temp;
        }

        if(total == num)
            System.out.println(num + " is an Armstrong number");
        else
            System.out.println(num + " is not an Armstrong number");
    }
}
Output:
Ënter 3 Digit Number
371
371 is an Armstrong number