Java Program to Check Armstrong Number

Posted in Java Tutorial

Updated on Jan 11, 2024

By Mari Selvan

👁️ 174 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the realm of programming, solving mathematical problems is a common task. One such interesting problem is checking whether a given number is an Armstrong number.

Armstrong numbers, also known as narcissistic numbers or pluperfect digital invariants, are numbers that are the sum of their own digits each raised to the power of the number of digits.

In this tutorial, we will explore a Java program designed to check whether a given number is an Armstrong number. The program involves calculating the sum of the digits raised to the power of the number of digits and comparing it with the original number.

📄 Example

Let's delve into the Java code that accomplishes this task.

ArmstrongNumber.java

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import java.util.Scanner;

public class ArmstrongNumber {

  // Function to check if a number is an Armstrong number
  static boolean isArmstrong(int number) {
    int originalNumber, remainder, n = 0, result = 0;

    // Assign the number to a temporary variable
    originalNumber = number;

    // Count the number of digits
    while (originalNumber != 0) {
      originalNumber /= 10;
      ++n;
    }

    // Assign the number to the originalNumber variable
    originalNumber = number;

    // Calculate the sum of nth power of individual digits
    while (originalNumber != 0) {
      remainder = originalNumber % 10;
      result += Math.pow(remainder, n);
      originalNumber /= 10;
    }

    // Check if the result is equal to the original number
    return result == number;
  }

  // Driver program
  public static void main(String[] args) {
    // Replace this value with the number you want to check
    int number = 153;

    // Call the function to check if the number is Armstrong
    if (isArmstrong(number))
      System.out.println(number + " is an Armstrong number.");
    else
      System.out.println(number + " is not an Armstrong number.");
  }
}

💻 Testing the Program

To test the program with different numbers, modify the value of number in the main program.

Output

153 is an Armstrong number.

🧠 How the Program Works

The program defines a class ArmstrongNumber containing a static method isArmstrong that takes an integer number as input and checks whether it is an Armstrong number.
Inside the main method, replace the value of number with the desired number you want to check.
The program calls the isArmstrong method and prints the result.

📏 Between the Given Range

Let's dive into the Java code that checks for Armstrong numbers in the specified range.

ArmstrongNumbers.java

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public class ArmstrongNumbers {

  // Function to check if a number is an Armstrong number
  static boolean isArmstrong(int number) {
    int originalNumber = number;
    int numDigits = String.valueOf(number).length();
    int sum = 0;

    while (number != 0) {
      int digit = number % 10;
      sum += Math.pow(digit, numDigits);
      number /= 10;
    }

    return sum == originalNumber;
  }

  // Driver program
  public static void main(String[] args) {
    System.out.println("Armstrong numbers in the range 1 to 50:");

    for (int i = 1; i <= 50; i++) {
      if (isArmstrong(i)) {
        System.out.print(i + " ");
      }
    }
  }
}

💻 Testing the Program

Output

Armstrong numbers in the range 1 to 50:
1 2 3 4 5 6 7 8 9

Simply compile and run the program. It will output the Armstrong numbers in the specified range.

🧠 How the Program Works

The program defines a class ArmstrongNumbers containing a static method isArmstrong that checks if a given number is an Armstrong number.
Inside the method, it calculates the number of digits in the number and then iterates through each digit, summing up the digits each raised to the power of the number of digits.
The main function tests the program by checking for Armstrong numbers in the range from 1 to 50 and printing the results.

🧐 Understanding the Concept of Armstrong Number

Before delving into the code, let's understand the concept behind Armstrong numbers. An Armstrong number is a number that is the sum of its own digits each raised to the power of the number of digits.

For example, 153 is an Armstrong number because 1^3 + 5^3 + 3^3 = 153.

🎢 Optimizing the Program

While the provided program is straightforward, consider exploring and implementing alternative approaches or optimizations for checking Armstrong numbers.

Feel free to incorporate and modify this code as needed for your specific use case. Happy coding!