﻿ Java exercises: Check whether a number is an Armstrong Number or not - w3resource # Java Exercises: Check whether a number is an Armstrong Number or not

## Java Numbers: Exercise-28 with Solution

Write a Program in Java to check whether a number is an Armstrong Number or not.

Armstrong (Michael F. Armstrong) number is a number that is equal to the sum of cubes of its digits. For example 0, 1, 153, 370, 371 and 407 are the Armstrong numbers

Sample Solution:

Java Code:

``````import java.util.*;
public class solution {
public static boolean is_Amstrong(int n) {
int remainder, sum = 0, temp = 0;
temp = n;
while (n > 0) {
remainder = n % 10;
sum = sum + (remainder * remainder * remainder);
n = n / 10;
}
return sum == temp;
}

public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Input an integer: ");
String input = scanner.nextLine();
int number = Integer.parseInt(input);
System.out.println("Is Armstrong number? "+is_Amstrong(number));
}
}
```
```

Sample Output:

```Input an integer:  153
Is Armstrong number? true
```

Flowchart: Java Code Editor:

What is the difficulty level of this exercise?

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## Java: Tips of the Day

Array vs ArrayLists:

The main difference between these two is that an Array is of fixed size so once you have created an Array you cannot change it but the ArrayList is not of fixed size. You can create instances of ArrayLists without specifying its size. So if you create such instances of an ArrayList without specifying its size Java will create an instance of an ArrayList of default size.

Once an ArrayList is full it re-sizes itself. In fact, an ArrayList is internally supported by an array. So when an ArrayList is resized it will slow down its performance a bit as the contents of the old Array must be copied to a new Array.

At the same time, it's compulsory to specify the size of an Array directly or indirectly while creating it. And also Arrays can store both primitives and objects while ArrayLists only can store objects.

Ref: https://bit.ly/3o8L2KH