﻿ Java exercises: Check whether a given number is an ugly number - w3resource # Java Exercises: Check whether a given number is an ugly number

## Java Numbers: Exercise-1 with Solution

Write a Java program to check whether a given number is an ugly number.

In number system, ugly numbers are positive numbers whose only prime factors are 2, 3 or 5. First 10 ugly numbers are 1, 2, 3, 4, 5, 6, 8, 9, 10, 12. By convention, 1 is included.

Test Data: Input an integer number: 235

Pictorial Presentation: Sample Solution:

Java Code:

``````import java.util.Scanner;
public class Exercise1 {
public static void main(String[] args){
Scanner in = new Scanner(System.in);
System.out.print("Input an integer number: ");
int n = in.nextInt();
if (n <= 0) {
System.out.print("Input a correct number.");
}
int x = 0;
while (n != 1) {
if (n % 5 == 0) {
n /= 5;
} else if (n % 3 == 0) {
n /= 3;
} else if (n % 2 == 0) {
n /= 2;
} else {
System.out.print("It is not an ugly number.");
x = 1;
break;
}
}
if (x==0)
System.out.print("It is an ugly number.");
System.out.print("\n");
}
}
```
```

Sample Output:

```Input an integer number: 235
It is not an ugly number.
```

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