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Java Exercises: Check if a number is palindrome or not

Java Numbers: Exercise-24 with Solution

Write a Java program to check if a number is palindrome or not.

In number system a palindromic number is a number that is the same when written forwards or backwards, i.e., of the form.
The first few palindromic numbers are therefore are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 22, 33, 44, 55, 66, 77, 88, 99, 101, 111, …

Test Data
Input a number: 5

Pictorial Presentation:

Java: Check if a number is palindrome or not.

Sample Solution:

Java Code:

import java.util.Scanner;
public class Example24  {

    public static void main(String args[])
    {
	 Scanner in = new Scanner(System.in);
     System.out.print("Input a number: ");
     int n = in.nextInt();
     int sum = 0, r;
	 int temp = n;    
     while(n>0)
	   {    
        r = n % 10;   
        sum = (sum*10)+r;    
        n = n/10;    
       }    
      if(temp==sum)    
        System.out.println("It is a Palindrome number.");    
      else    
        System.out.println("Not a palindrome");    
     }  
}

Sample Output:

Input a number: 5                                                                                             
It is a Palindrome number.

Flowchart:

Flowchart: Check if a number is palindrome or not

Java Code Editor:

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Next: Write a Java program to print the first 15 numbers of the Pell series.

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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