Hello Folks,
As part of Frequently Asked Java Programs In Interviews For Freshers And Experienced, in this post we will see a Java program to verify if a given string is palindrome without using inbuilt reverse method.
WHAT IS A PALINDROME STRING?
A palindromic string is a string that remains the same when its characters are reversed.
For Example: NAAN, AMMA AMMA etc.
Logic:
Since we can not use built in reverse method, so we will use different logic.
- We will convert given string in to char array first.
- Read char from char array from last index and concatenate.
Java Program:
package StringPrograms; import java.util.Scanner; public class PalindromeCharString { public static void main(String[] args) { // Reading string from user input Scanner sc = new Scanner(System.in); System.out.println("Please enter the string to check palindrome:"); String inputByUser = sc.nextLine(); // Closing input scanner sc.close(); // converting string in to char array char[] stringInChar = inputByUser.toCharArray(); // Declaring an empty string variable to store reverse string String reverseInput = ""; // reading char by char from end of array till first and forming a string for (int i = stringInChar.length - 1; i <= 0; i--) { reverseInput = reverseInput + stringInChar[i]; } // Printing both actual and reversed string System.out.println("Inout string:" + inputByUser); System.out.println("Reverse String:" + reverseInput); // Checking if given string is plaindrome if (inputByUser.equals(reverseInput)) System.out.println("Entered string is palindrome."); else System.out.println("Entered string is not palindrome."); } }
[java]
Output:
Please enter the string to check palindrome:
NANA
Inout string:NANA
Reverse String:ANAN
Entered string is not palindrome.
===============================================================
Please enter the string to check palindrome:
AMMA
Inout string:AMMA
Reverse String:AMMA
Entered string is palindrome.
[/java]
You can run above program for multiple inputs and if it fails for any condition, let me know.
#HappyCoding