Creating a recursive method for Palindrome

Question

I am trying to create a Palindrome program using recursion within Java but I am stuck, this is what I have so far:

 public static void main (String[] args){
         


        

Answer 1

Here is a recursive method that will ignore specified characters:

public static boolean isPal(String rest, String ignore) {
    int rLen = rest.length();
    if (rLen < 2)
        return true;
    char first = rest.charAt(0)
    char last = rest.charAt(rLen-1);
    boolean skip = ignore.indexOf(first) != -1 || ignore.indexOf(last) != -1;
    return skip || first == last && isPal(rest.substring(1, rLen-1), ignore);
}

Use it like this:

isPal("Madam I'm Adam".toLowerCase(), " ,'");
isPal("A man, a plan, a canal, Panama".toLowerCase(), " ,'");

It does not make sense to include case insensitivity in the recursive method since it only needs to be done once, unless you are not allowed to use the .toLowerCase() method.