Armstrong Number In Java Program – 5 Simple Ways

Armstrong number in Java. Here we written the code in four different ways standard, using for loop, recursion, while loop and also with different examples as like: between 100 and 999, between 1 to 1000 and between 1 to 500 with sample outputs and online execution tool embedded.

What is Armstrong Number ?

A: An Armstrong number of three digits is an integer, where the sum of the cubes of it’s digits is equal to the number it self.

Sr.NO	Table Of Contents
1	while Loop ( 1 to 500 )
2	Recursion ( Between 1 to 1000 )
3	Using for loop ( 100 to 500 )
4	BufferedReader

Here is the example for you :

Consider the example : 371

A: 3^3 + 7^3 + 1^3 = 371 ( If you add those all numbers, the final digit should be same a s given number ).

Here is the list of Java programs with different methods in a different ways. Do check out the table of contents so that you will get an idea.

Armstrong Number In Java Program

1. Using static method Between 100 and 999

Here is the first sample program using static method with sample output as well. Here we used the method ‘ Static ‘ and taken numbers between 100 to 999. Once you done with the execution it automatically displays the Armstrong numbers between 100 and 999. Check out the sample output.

import java.util.Scanner;
class ArmstrongWhile
{
	public static void main(String[] arg)
	{
	int i=100,arm;
	System.out.println("Armstrong numbers between 100 to 999");
	while(i<1000)
	{
	arm=armstrongOrNot(i);
	if(arm==i)
	System.out.println(i);
	i++;
	}
	}
static int armstrongOrNot(int num)
{
	int x,a=0;
	while(num!=0)
	{
		x=num%10;
		a=a+(x*x*x);
		num/=10 ;
	}
	return a;
}
}

import java.util.Scanner;

class ArmstrongWhile

{

public static void main(String[] arg)

{

int i=100,arm;

System.out.println("Armstrong numbers between 100 to 999");

while(i<1000)

{

arm=armstrongOrNot(i);

if(arm==i)

System.out.println(i);

i++;

}

static int armstrongOrNot(int num)

{

int x,a=0;

while(num!=0)

{

x=num%10;

a=a+(x*x*x);

num/=10 ;

}

return a;

}

Output:

Armstrong numbers between 100 to 999
153
370
371
407

Armstrong numbers between 100 to 999

153

370

371

407

2. Using while Loop ( 1 to 500 )

There you go another method using while loop. Java while loop is nothing but executing a set of statements repeatedly as long as condition is true – here is the complete guide on while loop in Java with examples. In this case, we taken the example of numbers from 1 to 500. Upon execution you will get to know what are arm;strng numbers. Check out output below so that you will get an idea.

class ArmstrongWhile
{
	public static void main(String[] arg)
	{
	int i=1,a,arm,n,temp;
	System.out.println("Armstrong numbers between 1 to 500 are");
	while(i<500)
	{
	n=i;
	arm=0;
	while(n>0)
	{
		a=n%10;
		arm=arm+(a*a*a);
		n=n/10;
	}
	if(arm==i)
		System.out.println(i);
	i++;
	}
	}
}

class ArmstrongWhile

{

public static void main(String[] arg)

{

int i=1,a,arm,n,temp;

System.out.println("Armstrong numbers between 1 to 500 are");

while(i<500)

{

n=i;

arm=0;

while(n>0)

{

a=n%10;

arm=arm+(a*a*a);

n=n/10;

}

if(arm==i)

System.out.println(i);

i++;

}

Output:

Armstrong numbers between 1 to 500 are
1
153
370
371
407

Armstrong numbers between 1 to 500 are

153

370

371

407

3. Using Recursion ( Between 1 to 1000 )

Another method using recursion : A function that calls itself is called recursion. Here is the complete code with sample program and output of the program. Here we taken the example of numbers from 1 to 1000. Check it out.

import java.util.Scanner;
class ArmstrongRecursion
{
	int x;
	int findArmstrong(int n,int a)
	{
	if(n!=0)
	{
		x=n%10;
		a=a+(x*x*x);
		n/=10 ;
		return findArmstrong(n,a);
	}
	return a;
	}
	public static void main(String[] arg)
	{
	ArmstrongRecursion A=new ArmstrongRecursion();
	int arm;
	System.out.println("Armstrong numbers between 1 to 1000");
	for(int num=1;num<500;num++)
	{
	arm=A.findArmstrong(num,0);
	if(arm==num)
	      System.out.println(num);
	}
	}
}

import java.util.Scanner;

class ArmstrongRecursion

{

int x;

int findArmstrong(int n,int a)

{

if(n!=0)

{

x=n%10;

a=a+(x*x*x);

n/=10 ;

return findArmstrong(n,a);

}

return a;

}

public static void main(String[] arg)

{

ArmstrongRecursion A=new ArmstrongRecursion();

int arm;

System.out.println("Armstrong numbers between 1 to 1000");

for(int num=1;num<500;num++)

{

arm=A.findArmstrong(num,0);

if(arm==num)

System.out.println(num);

}

Output:

Armstrong numbers between 1 to 1000
1
153
370
371
407

Armstrong numbers between 1 to 1000

153

370

371

407

4. Using BufferedReader

There you another method using Bufferedreader. Do check it out.

import java.io.*;
class ArmstrongBuf
{
	public static void main(String[] arg) throws IOException
	{
	int a,arm=0,n,temp;
	BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
	System.out.println("Enter a number");
            	n = Integer.parseInt(in.readLine());
	temp=n;
	while(n!=0)
	{
		a=n%10;
		arm=arm+(a*a*a);
		n=n/10;
	}
	if(arm==temp)
	System.out.println(temp+" is a armstrong number ");
	else
	System.out.println(temp+" is not a armstrong number ");
}
}

import java.io.*;

class ArmstrongBuf

{

public static void main(String[] arg) throws IOException

{

int a,arm=0,n,temp;

BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

System.out.println("Enter a number");

n = Integer.parseInt(in.readLine());

temp=n;

while(n!=0)

{

a=n%10;

arm=arm+(a*a*a);

n=n/10;

}

if(arm==temp)

System.out.println(temp+" is a armstrong number ");

else

System.out.println(temp+" is not a armstrong number ");

}

Output:

Enter a number
153
153 is a armstrong number

Enter a number

153

153 is a armstrong number

5. Using for loop ( 100 to 500 )

Another sample program to print armstrong number using for loop. Check out the program along with the sample output.

import java.util.Scanner;
class Armstrong
{
	public static void main(String[] arg)
	{
	int a,arm=0,n,temp;
	Scanner sc=new Scanner(System.in);
	System.out.println("Enter a number");
	n=sc.nextInt();
	temp=n;
	for( ;n!=0;n/=10 )
	{
		a=n%10;
		arm=arm+(a*a*a);
	}
	if(arm==temp)
	System.out.println(temp+" is a armstrong number ");
	else
	System.out.println(temp+" is not a armstrong number ");
        }
}

import java.util.Scanner;

class Armstrong

{

public static void main(String[] arg)

{

int a,arm=0,n,temp;

Scanner sc=new Scanner(System.in);

System.out.println("Enter a number");

n=sc.nextInt();

temp=n;

for( ;n!=0;n/=10 )

{

a=n%10;

arm=arm+(a*a*a);

}

if(arm==temp)

System.out.println(temp+" is a armstrong number ");

else

System.out.println(temp+" is not a armstrong number ");

}

That’s it. If you have any doubts related to the above code. Juts leave a comment here at the end of the post. We do try to help you out related to ant query asap.

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