java string palindrome program code example

Example 1: easy palindrome program in java

import java.util.*;   
class PalindromeExample2  
{  
   public static void main(String args[])  
   {  
      String original, reverse = ""; // Objects of String class  
      Scanner in = new Scanner(System.in);   
      System.out.println("Enter a string/number to check if it is a palindrome");  
      original = in.nextLine();   
      int length = original.length();   
      for ( int i = length - 1; i >= 0; i-- )  
         reverse = reverse + original.charAt(i);  
      if (original.equals(reverse))  
         System.out.println("Entered string/number is a palindrome.");  
      else  
         System.out.println("Entered string/number isn't a palindrome.");   
   }  
}

Example 2: String palindrome in java using array

// String palindrome in java using array
import java.util.Arrays;
import java.util.Scanner;
public class StringPalindromeUsingArray 
{
   public static void main(String[] args) 
   {
      System.out.println("Please enter string to check whether string is palindrome: ");
      Scanner sc = new Scanner(System.in);
      String strInput = sc.nextLine();
      char[] chArray = strInput.toCharArray();
      int size = chArray.length;
      char[] chGiven = Arrays.copyOf(chArray, chArray.length);
      for(int a = 0; a < size / 2; a++) 
      {
         char temp = chArray[a];
         chArray[a] = chArray[size - a - 1];
         chArray[size - a - 1] = temp;
      }
      System.out.println("Given array: " + Arrays.toString(chGiven));
      System.out.println("String palindrome using array: " + Arrays.toString(chArray));
      if(Arrays.equals(chArray, chGiven)) 
      {
         System.out.println("string is palindrome.");
      }
      else 
      {
         System.out.println("string is not a palindrome.");
      }
      sc.close();
   }
}

Example 3: java program to find plaindrome

public class Palindrome {

    public static void main(String[] args) {

        int num = 121, reversedInteger = 0, remainder, originalInteger;

        originalInteger = num;

        // reversed integer is stored in variable 
        while( num != 0 )
        {
            remainder = num % 10;
            reversedInteger = reversedInteger * 10 + remainder;
            num  /= 10;
        }

        // palindrome if orignalInteger and reversedInteger are equal
        if (originalInteger == reversedInteger)
            System.out.println(originalInteger + " is a palindrome.");
        else
            System.out.println(originalInteger + " is not a palindrome.");
    }
}