Palindrome 1

PalindromeChecker.java

public class PalindromeChecker {
    public static void main(String[] args) {
        String sWordToCheck = "malam";

        System.out.println("Using palindrome1 : ");
        if(isPalindrome1(sWordToCheck))
            System.out.println(sWordToCheck + " Is Palindrome ");
        else
            System.out.println(sWordToCheck + " Is Not Palindrome ");

        System.out.println("\n");

        System.out.println("Using palindrome2 : ");
        if(isPalindrome2(sWordToCheck))
            System.out.println(sWordToCheck + " Is Palindrome ");
        else
            System.out.println(sWordToCheck + " Is Not Palindrome ");

        System.out.println("\n");

        System.out.println("Using palindrome3 : ");
        if(isPalindrome2(sWordToCheck))
            System.out.println(sWordToCheck + " Is Palindrome ");
        else
            System.out.println(sWordToCheck + " Is Not Palindrome ");


    }


    public static boolean isPalindrome3(String sWordToCheck) {
        return sWordToCheck.equals(new StringBuffer(sWordToCheck).reverse().toString());
    }

    public static boolean isPalindrome1(String word) {
        int left = 0;                 // index of leftmost unchecked char
        int right = word.length() - 1;  // index of the rightmost

        while (left < right) {         // continue until they reach center
            if (word.charAt(left) != word.charAt(right)) {
                return false;          // if chars are different, finished
            }
            left++;                    // move left index toward the center
            right--;                   // move right index toward the center
        }

        return true;                   // if finished, all chars were same
    }


    public static boolean isPalindrome2(String sWord) {
        int len = sWord.length();
        for (int i = 0; i < (len % 2); i++) {
            if (sWord.charAt(i) != sWord.charAt(len - i - 1)) {
                return false;
            }
        }

        return true;
    }
}

len%2 is either 0 or 1 (since it's the remainder of n divided by 2)
so, depending on whether len is even, this loop will either make 0 iterations or just 1, and return true on ALL strings of even length (say "bbbaaa") and true on ALL strings of odd length that have the same first and last character (say "maabccm").

look at the head revision of my fork, I added several more test cases and fixed the function