﻿ Java exercises: Check a number is a cube or not - w3resource # Java Exercises: Check a number is a cube or not

## Java Numbers: Exercise-18 with Solution

Write a Java program to check a number is a cube or not.

In arithmetic and algebra, the cube of a number n is its third power: the result of the number multiplied by itself twice:
n3 = n × n × n
Input Data:
Input a number: 8

Pictorial Presentation: Sample Solution:

Java Code:

``````import java.util.Scanner;
public class Example18 {

public static void main( String args[] ){
Scanner sc = new Scanner( System.in );
System.out.print("Input a number: ");
int num = sc.nextInt();
int n = (int) Math.round(Math.pow(num, 1.0/3.0));
if((num == n * n * n))
{
System.out.print("Number is a cube.");
}
else
{
System.out.print("Number is not a cube.");
}
System.out.println("\n");
}
}
```
```

Sample Output:

```Input a number: 8
Number is a cube.
```

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