How to check whether given String is palindrome or not in Java?

Problem Description :

Write a program in Java that checks whether given String is palindrome or not.

String is Palindrome or not?

Concept :

If any string is same from both the sides then we can say, string is palindrome. For example - "raman" is not a palindrome but "naman" is palindrome. There are 2 ways to check whether string is palindrome or not. Library function and Iteration. We will discuss both methods here.

Java Program :

1) Library function

Here we are finding reverse of string using library function of StringBuilder class and then comparing given string with reversed string.

package com.javamultiplex.string; import java.util.Scanner; /** * * @author Rohit Agarwal * @category String Problems * @problem String is palindrome or not? * */ public class StringPalindrome { /** * There are 2 ways to check whether String is Palindrome or not. * 1.Using library function of String class. * 2.Using Iteration. * * Here we are using 1st method - using library function of String class */ public static void main(String[] args) { Scanner input = null; try { input = new Scanner(System.in); System.out.println("Enter String : "); String string = input.next(); /** * There are 3 ways to Reverse any String. * 1. Using library function of StringBuilder class. * 2. Using Iteration method. * 3. Using Recursion method. * * Here we are using 1st method - using library function. */ StringBuilder stringBuilder = new StringBuilder(string); String newString = stringBuilder.reverse().toString(); if (string.equals(newString)) { System.out.println("String is Palindrome."); } else { System.out.println("String is not Palindrome."); } } finally { if (input != null) { input.close(); } } } }

2) Iteration

Here we are using for loop and comparing first and last character of string till its half length.

package com.javamultiplex.string; import java.util.Scanner; /** * * @author Rohit Agarwal * @category String Problems * @problem String is palindrome or not? * */ public class StringPalindromeUsingIteration { /** * There are 2 ways to check whether String is Palindrome or not. * 1.Using library function of String class. * 2.Using Iteration. * * Here we are using 2nd method - using Iteration. */ public static void main(String[] args) { Scanner input = null; try { input = new Scanner(System.in); System.out.println("Enter String : "); String string = input.next(); int length = string.length(); int j = length - 1; int count = 0, halflength = length / 2; for (int i = 0; i < halflength; i++) { if (string.charAt(i) == string.charAt(j)) { count++; } else { break; } j--; } if (count == halflength) { System.out.println("String is Palindrome."); } else { System.out.println("String is not Palindrome."); } } finally { if (input != null) { input.close(); } } } }

Output :

Case 1 :

Output - String is not Palindrome.

Case 2 :

Output - String is Palindrome.

References :

https://en.wikipedia.org/wiki/Palindrome

https://docs.oracle.com/javase/7/docs/api/java/lang/StringBuilder.html#reverse()

https://docs.oracle.com/javase/7/docs/api/java/lang/String.html

https://docs.oracle.com/javase/7/docs/api/java/lang/StringBuilder.html

Thank you friends, I hope you have clearly understood the solution of this problem. If you have any doubt, suggestion or query please feel free to comment below. You can also discuss this solution in our forum.

Tags : Date and Time problems, String is Palindrome or not in Java, Solution in Java, if else statement, for loop, while loop, Iteration, Reverse, String, StringBuilder.

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How to check whether given String is palindrome or not in Java?

Problem Description :

Concept :

Recommended :

Java Program :

1) Library function

2) Iteration

Output :

Case 1 :

Case 2 :

References :

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