Palindrome string in java

Hey guys!! Welcome to flower brackets blog. In this post we are going to learn palindrome string in java.Palindrome string in javaPalindrome string, is a string where string remains same when reversed or a word spelled same way forwards and backwards.Example : level, dad, mom, madam, abcba, etc.,

Also read – palindrome program in java using library methods

In the below java program user enters a string as input. Then input string is reversed using for loop. Lastly this reversed string is compared with input string.
import java.util.*;

public class PalindromeStringInJava 
{
   public static void main(String[] args) 
   { 
      String strInput, strPalindrome = "";
      Scanner sc = new Scanner(System.in);
      System.out.print("Please enter the string : ");
      strInput = sc.nextLine();
      int num = strInput.length();
      for(int a = num - 1; a >= 0; a--)
      {
         strPalindrome = strPalindrome + strInput.charAt(a);
      }
      if(strInput.equalsIgnoreCase(strPalindrome))
      {
         System.out.println("String is palindrome.");
      }
      else
      {
         System.out.println("String is not palindrome.");
      }
      sc.close();
   }
}

Output:Please enter the string : mom String is palindrome.
Similarly we can execute above program without reversing a string. In this program characters at beginning and at end move towards middle of the string.
import java.util.Scanner;

public class PalindromeStringDemo 
{
   public static void main(String[] args) 
   {
      Scanner sc = new Scanner(System.in);
      System.out.println("Enter a string : ");
      String str = sc.nextLine();

      int length = str.length();
      int a, start, end, middle;

      start = 0;
      end = length - 1;
      middle = (start + end) / 2;

      for(a = start; a <= middle; a++) 
      {
         if(str.charAt(start) == str.charAt(end)) 
         {
            start++;
            end--;
         }
         else
         {
            break;
         }
      }
      if(a == middle + 1) 
      {
         System.out.println(str + " - palindrome string.");
      }
      else
      {
         System.out.println(str + " - not a palindrome string.");
      }
      sc.close();
   }
}

Output:Enter a string : level level – palindrome string.

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