Find all substrings that are palindromes

Question

If the input is \'abba\' then the possible palindromes are a, b, b, a, bb, abba.
I understand that determining if string is palindrome is easy. It would be like:

Answer 1

Code is to find all distinct substrings which are palindrome. Here is the code I tried. It is working fine.

import java.util.HashSet;
import java.util.Set;

public class SubstringPalindrome {

    public static void main(String[] args) {
        String s = "abba";
        checkPalindrome(s);
}

public static int checkPalindrome(String s) {
    int L = s.length();
    int counter =0;
    long startTime = System.currentTimeMillis();
    Set hs = new HashSet();
    // add elements to the hash set
    System.out.println("Possible substrings: ");
    for (int i = 0; i < L; ++i) {
      for (int j = 0; j < (L - i); ++j) {
          String subs = s.substring(j, i + j + 1);
            counter++;
            System.out.println(subs);
            if(isPalindrome(subs))
                hs.add(subs);
      }
    }
    System.out.println("Total possible substrings are "+counter);
    System.out.println("Total palindromic substrings are "+hs.size());
    System.out.println("Possible palindromic substrings: "+hs.toString());
    long endTime = System.currentTimeMillis();
    System.out.println("It took " + (endTime - startTime) + " milliseconds");
    return hs.size();
}
public static boolean isPalindrome(String s) {
    if(s.length() == 0 || s.length() ==1)
        return true;
    if(s.charAt(0) ==  s.charAt(s.length()-1))
        return isPalindrome(s.substring(1, s.length()-1));
    return false;
}

}

OUTPUT:

Possible substrings: a b b a ab bb ba abb bba abba

Total possible substrings are 10

Total palindromic substrings are 4

Possible palindromic substrings: [bb, a, b, abba]

It took 1 milliseconds