Java Program to Check Armstrong Number

What is Armstrong Number ?

In an Armstrong Number, the sum of power of individual digits is equal to number itself.

In other words the following equation will hold true

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

n is number of digites in number

For example this is a 3 digit Armstrong number

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

Examples of Armstrong Numbers

 0, 1, 4, 5, 9, 153, 371, 407, 8208, etc.

Let’s write this in a program:

Java Program to check whether a number is Armstrong Number

//ChecktempNumber is Armstrong or not using while loop
package com.guru99;
 
public class ArmstrongNumber {
 
 public static void main(String[] args) {
  
   int inputArmstrongNumber = 153; //Input number to check armstrong  
   int tempNumber, digit, digitCubeSum = 0;
 
        tempNumber = inputArmstrongNumber;
         while (tempNumber != 0)
         {
          
          /* On each iteration, remainder is powered by thetempNumber of digits n
           */
             System.out.println("Current Number is "+tempNumber);
             digit =tempNumber % 10;
    System.out.println("Current Digit is "+digit);
             //sum of cubes of each digits is equal to thetempNumber itself
             digitCubeSum = digitCubeSum + digit*digit*digit;
    System.out.println("Current digitCubeSum is "+digitCubeSum);
             tempNumber /= 10;
            
         }
 
         //check giventempNumber and digitCubeSum is equal to or not 
         if(digitCubeSum == inputArmstrongNumber)
             System.out.println(inputArmstrongNumber + " is an Armstrong Number");
         else
             System.out.println(inputArmstrongNumber + " is not an Armstrong Number");
 
 }
 
}

Output

Current Number is 153
Current Digit is 3
Current digitCubeSum is 27
Current Number is 15
Current Digit is 5
Current digitCubeSum is 152
Current Number is 1
Current Digit is 1
Current digitCubeSum is 153
153 is an Armstrong Number

Java Program to Print Armstrong numbers from 0 to 999

//ChecktempNumber is Armstrong or not using while loop
package com.guru99;
 
public class ArmstrongNumber {
 
    public static void main(String[] args) {
        int tempNumber, digit, digitCubeSum;
 
        for (int inputArmstrongNumber = 0; inputArmstrongNumber < 1000; inputArmstrongNumber++) {
            tempNumber = inputArmstrongNumber;
            digitCubeSum = 0;
            while (tempNumber != 0) {
 
                /* On each iteration, remainder is powered by thetempNumber of digits n
                 */
 
                digit = tempNumber % 10;
 
                //sum of cubes of each digits is equal to thetempNumber itself
                digitCubeSum = digitCubeSum + digit * digit * digit;
 
                tempNumber /= 10;
 
            }
 
            //check giventempNumber and digitCubeSum is equal to or not 
            if (digitCubeSum == inputArmstrongNumber)
                System.out.println(inputArmstrongNumber + " is an Armstrong Number");
 
        }
 
    }
 
}

Output

0 is an Armstrong Number
1 is an Armstrong Number
153 is an Armstrong Number
370 is an Armstrong Number
371 is an Armstrong Number
407 is an Armstrong Number