PalindromeTest.java

public class PalindromeTest {

    public static void main(String[] args) {
        String[] s = { "racecar",
            "Race fast, safe car!",
            "Madame, not one man is selfless; I name not one, madam.",
            "Tuna roll or a nut?",
            "Ya! Pizza zip pizazz! I pay."
        };

        for(int k=0; k<s.length; k++) {
            System.out.print( "\"" + s[k] + "\"");
            if (isPalindrome( s[k])) {
                System.out.println(" is a palindrome.");
            } else {
                System.out.println(" is not a palindrome.");
            }
        }
    }

    public static boolean isPalindrome(String s) {
        s = s.toLowerCase().replaceAll("\\W", "");
        char first = s.charAt(0);
        char last  = s.charAt(s.length()-1);

        if (first != last ) return false;
        if (s.length() <= 2) return true;
        // recursive function call
        return isPalindrome( s.substring(1, s.length()-1));
    }
}