Palindrome String in Java — Definition, Examples and Program

Palindrome String in Java — Definition, Examples and Program

A palindrome string is a string that reads the same forward and backward. Palindrome checking is a classic string problem that helps understand loops, indexing, and comparisons.

In this blog, you will learn:

• What a palindrome string is
• Step-by-step examples
• A simple Java program
• Practice challenges

What Is a Palindrome String?

A string is called a palindrome if the characters from left to right are the same as from right to left.

Examples:

• "madam"
• "level"
• "radar"

Non-Palindrome Examples:

• "java"
• "hello"

How the Logic Works

To check whether a string is a palindrome:

1. Compare the first and last characters.
2. Move inward toward the center.
3. If any mismatch occurs, the string is not a palindrome.

Example 1

Input: "LEVEL"

• Compare 'L' and 'L' → match
• Compare 'E' and 'E' → match
• Compare 'V' → middle character

Output: Palindrome String

Example 2

Input: "JAVA"

• Compare 'J' and 'A' → mismatch

Output: Not a Palindrome String

Java Program to Check Palindrome String

import java.util.Scanner;

public class PalindromeString {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a string: ");
        String input = sc.nextLine();

        boolean isPalindrome = true;
        int start = 0;
        int end = input.length() - 1;

        while (start < end) {
            if (input.charAt(start) != input.charAt(end)) {
                isPalindrome = false;
                break;
            }
            start++;
            end--;
        }

        if (isPalindrome) {
            System.out.println("Palindrome String");
        } else {
            System.out.println("Not a Palindrome String");
        }
    }
}

Sample Output

Enter a string: madam
Palindrome String

Enter a string: coding
Not a Palindrome String

Practice Challenges

1. Check whether a string is a palindrome without using extra variables.
2. Ignore case sensitivity while checking palindrome (e.g., "Madam").
3. Check palindrome for a full sentence by ignoring spaces.

Palindrome checking is a common interview question and builds a strong foundation in string manipulation. Once mastered, you can easily solve advanced string problems.