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In this tutorial, we will write a Java Program to check Armstrong number. We will write two different programs to check the armstrong number in java.

1. What is an Armstrong number?
2. Java program to check the Armstrong Number(for any digit number) using a while and for.
3. Java program to check the Armstrong Number(using Math.pow() method).

What is an Armstrong Number?

A number is said to be an Armstrong Number if even after the sum of its digits, where each digit is raised to the power of the number of digits is equal to the original number. For example 153, 371, 407, 9474, etc are Armstrong Numbers.

Follow the below calculation.

Java program to check the Armstrong Number using while and for loops

import java.util.Scanner;
 
 public class ArmstrongNumber
 {
  public static void main(String[] args)
  {
    int n, num, totalDigits, remainder, result = 0;
 
    System.out.println("Enter the Number:");
    Scanner scanner = new Scanner(System.in);
    
    n = scanner.nextInt();
    scanner.close();
    
    //setting the power to the no. of digits
    totalDigits = String.valueOf(n).length();
    
    num = n;
 
    while (num != 0)
    {
        remainder = num % 10;
        int lastDigits = 1;
        
        for(int i = 0; i < totalDigits; i++)
         {
           lastDigits = lastDigits * remainder;
         }
         
        result = result + lastDigits;
        num /= 10;
    }
 
    if(result == n)
        System.out.println(n + " is an Armstrong number.");
    else
        System.out.println(n + " is not an Armstrong number.");
  }
 }

Output: You can check for any digit Number.

Enter the Number:
9474
9474 is an Armstrong number.

Explanation:
First we create required variables(n, num, totalDigits, remainder, result). Get User Input and store it in n, then we need the number of digits present in that number and store it n totalDigits using code (totalDigits = String.valueOf(n).length();). After that, copy the entered number to num.

Now start the while loop checking num is not equal to zero. While stops as soon as num becomes zero.
After each iteration of the while loop, the last digit of num is stored in remainder for the second use. We initiate an int variable lastDigits = 1.

Now the for loop runs until the totalDigits less than i where is initiated as 0 and increase by 1 after each iteration. Inside for loop lastDigits is multiplied to remainder and the result is added to lastDigits.

After the end of for loop, the value of lastDigits is assigned to the result variable.
and at the end, we divide the num by 10 i.e num /= 10; which will remove the last digit from the number.
This step is continued until the num becomes 0.

At last, we will check with if-else statement whether the result is equal to the original number or not. If it is found equal,l then the entered number is an Armstrong Number.

Java program to check the Armstrong Number using Math.pow() method

 //check for armstrong number
  
import java.util.Scanner;
 
 public class ArmstrongNumber
 {
  public static void main(String[] args)
  {
    int n, num, power, remainder, result = 0;
 
    
    System.out.print("Enter the Number: ");
    Scanner scanner = new Scanner(System.in);
    
    n = scanner.nextInt();
    scanner.close();
    
    //seting the power to the no. of digits
    power = String.valueOf(n).length();
    
    num = n;
 
    while (num != 0)
    {
        remainder = num % 10;
        result += Math.pow(remainder, power);
        num /= 10;
    }
 
    if(result == n)
        System.out.println(n + " is an Armstrong number.");
    else
        System.out.println(n + " is not an Armstrong number.");
  }
 }

Output: You can check for any digit Number.

Enter the Number: 370
370 is an Armstrong number

Explanation: In the above program we use the inbuilt method (Math.pow()) which makes it easy for us to calculate the raised power to the number.

The process is the same as explained above, only the difference is instead of for loop we use the method(Math.pow()) as result += Math.pow(remainder, power);.

If we were to calculate for the only three-digit number then we can simply replace the code:
result += Math.pow(remainder, power); with
result = result + remainder*remainder*remainder;

In this java program tutorial, we will write a java program to display the Fibonacci series. Let us first understand what is Fibonacci series is and then the Java program to generate them.

What is Fibonacci Series?

Fibonacci series is the series of numbers where the next number is achieved by the addition of the previous two numbers. The initial addition of two numbers is 0 and 1.

For example: 0,1,1,2,3,5,8,13….etc.

We will see two ways to print the Fibonacci Series.

• With the help of iteration(for-loop).
• Using recursion.

Program Explanation:
First, we need to initialize the two terms as 0 and 1 as a = 0, b = 0; then get user input for the total number of elements in a series which is stored in an integer variable n.

After that start iteration up to the number of elements the user inputs. Inside for loop, we assigned the b value in a and the sum value in b and the sum is the addition of a and b. Then we print the value at every iteration as shown in a program.

At last, the program exits the iteration when integer i is less than or equal to the number of elements as,
i <= n.

1. Java program to display Fibonacci series using for loop

//Fibonacci series in java

import java.util.Scanner;

public class FibonacciJava
{
  public static void main(String[] args)
  {
    int n, a = 0, b = 0, sum = 1;

    Scanner s = new Scanner(System.in);

    System.out.print("Enter the Number:");
    n = s.nextInt();

    System.out.print("Fibonacci Series of entered number are:");
    for (int i = 1; i <= n; i++)	//display
    {
      a = b;
      b = sum;
      sum = a + b;
      System.out.print(a + " ");
    }
  }
}

Output:

Enter the Number:6
Fibonacci Series of entered number are:0 1 1 2 3 5

2. Fibonacci series using Recursion in java

//Fibonacci Using Recursion

import java.util.Scanner;
public class FiboSeries
{
    public static int fiboRecursion(int n)
    {
     if(n == 0)
     {
       return 0;
     }
     if(n == 1 || n == 2)
     {
       return 1;
     }
     return fiboRecursion(n-2) + fiboRecursion(n-1);
    }
	
  public static void main(String args[]) 
  {
    int number;
    Scanner s = new Scanner(System.in);
        
    System.out.print("Enter the Number:");
    number = s.nextInt();
        
    System.out.print("Fibonacci Series of entered number: ");
	
    for(int i = 0; i < number; i++)
    {
	System.out.print(fiboRecursion(i) +" ");
    }
  }
}

After executing, the following output will be obtained.

Enter the Number:8
Fibonacci Series of entered number: 0 1 1 2 3 5 8 13

Here you will learn how Swap two numbers using the third Variable.

The program declares a temp variable to temporarily store the value of one of the two values. If you want to know how to swap numbers without using a third variable, click the link below.

• Java Program to Swap Two Numbers Without using the Third Variable

Java Program to Swap two numbers using Third Variable

 //swap two number

 import java.util.*;

 public class SwapTwoNumbersJava
 {
  public static void main(String []s)
  {
    int a, b, temp;
    
    Scanner sc=new Scanner(System.in);

    System.out.print("Enter value of a: ");
    a=sc.nextInt();
    
    System.out.print("Enter value of b: ");
    b=sc.nextInt();

    System.out.println("Values before swapping - a: "+ a +", b: " + b);
    
    //swap
    temp=a;
    a=b;
    b=temp;
    
    //displaying after swap
    System.out.println("Values after swapping  - a: "+ a +", b: " + b);
  }
 }

Output:

 Enter value of a: 24
 Enter value of b: 25
 Values before swapping - a: 24, b: 25
 Values after swapping  - a: 25, b: 24

Division in Java:

This article will show you the process to divide in Java with output.

The division is one of the basic operations in java. Others include addition, subtraction, and multiplication. For dividing in java, a division operator (/)is used. This operator takes two operands(the natural numbers to be divided) to divide them.

We will see two ways for java division:

• First by declaring the number to be divided inside the program.
• Second by taking the user input.

1. Java Program to divide two numbers.

public class DivisionJava 
{
 public static void main(String[] args) 
 {
 //declaring operands
 float num1 = 70, num2 = 3;
 
 //division
 float result = num1/num2;
 
 //Display
 System.out.println("The result is: "+result);
 }
}

The output of the division in java:

The result is: 23.333334

2. Java Program to Divide two Numbers taking User’s Input

import java.util.Scanner;

public class JavaDivision 
{
  public static void main(String[] args) 
  {
    Scanner input = new Scanner (System.in);
    
    System.out.print("Enter the first number (Denominator): ");
    int num1 = input.nextInt();
    
    System.out.print("Enter the second number (Numerator): ");
    int num2 = input.nextInt();
    
    //Division
    int result = (num1/num2);

    System.out.println("\nThe result of division is:" +result);
  }
}

The output of the user input division in Java:

Enter the first number (Denominator): 70
Enter the second number (Numerator): 3

The result of division is:23.333334

This post covers the Java Program to swap two numbers without using the third variable. It is easy to swap two numbers using the third variable, we assigned one to a temporary(temp) variable and swap with others.

• Swap two numbers using third variable in java

Now let us see without using the third variable.

Explanation:
With the help of a Scanner class, we take the user input for two integers (a = 5, b = 3).
Now during the process of swapping, we assigned the value of a equal to the sum of a and b that is,
a = a + b;
(a = 5+3 = 8).

Second, we assigned the value of b equal to the difference between a and b that is,
b = a - b
(b= 8 – 3 = 5).

Lastly, we assigned the value of a equal to the difference between a and b that is,
a = a - b
(a= 8 – 5 = 3).

Then print those swapped values as shown in the program below.

Java program to swap two numbers without using Third Variable

//Swapping of two numbers

import java.util.Scanner;
class SwapTwoNumbers
{
   public static void main(String args[])
   {

    int a, b;
    System.out.println("Enter the two numbers, a and b");

    Scanner in = new Scanner(System.in);

    a = in.nextInt();
    b = in.nextInt();
  
    System.out.println("Values before Swapping\na = "+a+"\nb = "+b);
    
    a = a + b;
    b = a - b;
    a = a - b;

    System.out.println("Values after Swapping without third variable\na = "+a+"\nb = "+b);
   }
}

Output: