Write a Java program to check if String is Palindrome using StringBuilder.

The StringBuilder in Java represents a mutable sequence of characters. Since the String Class in Java creates and immutable sequence of characters, the StringBuilder class provides an alternate to String Class, as it creates a mutable sequence of characters. 

package testjava.javatest;

import java.util.Scanner;

public class StringPalinBuilder
{
	public static void main(String args[])
	{
		Scanner reader = new Scanner(System.in);
		
		System.out.print("Please enter a String: ");
		String input = reader.nextLine();
		
		System.out.printf("Is %s a palindrome? : %b %n", input, isPalindrome(input));
		
		System.out.print("Please enter another String: ");
		input = reader.nextLine();
		
		System.out.printf("Is %s a palindrome? : %b %n", input, isPalindrome(input));
		reader.close();
	}

	public static boolean isPalindrome(String inputStr)
	{
		if (inputStr == null || inputStr.isEmpty()) 
		{
			return true;
		}
	
		char[] array = inputStr.toCharArray();
	
		StringBuilder sb = new StringBuilder(inputStr.length());
	
		// Add each char of inputStr to StringBuilder from reverse
		for (int i = inputStr.length() - 1; i >= 0; i--)
		{
			sb.append(array[i]);
		}

		String reverseOfString = sb.toString();
		
		//Compare 2 strings input and reverseOfString
		return inputStr.equals(reverseOfString);
	}
} 

Output

Please enter a String: Hello
Is Hello a palindrome? : false 
Please enter another String: wow
Is wow a palindrome? : true