Converting Youtube Data API V3 video duration (e.g. PT1H9M24S ) to hh:mm:ss format in java

TimeConverter.java

package com.vkdinventor.code;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Created by vikash on 01-04-2017.
 */
public class TimeConverter {

    public static void main(String[ ] args){
        String [] s = new String[]{"PT1H9M24S","PT1H1S","PT2H1S","PT23H2M","PT23M2S","PT31S","PT"};
        for (String input:s){
            System.out.println(new TimeConverter().converttoHHMMSS(input));
        }
    }
    public String converttoHHMMSS(String youtubetime) {

        String pattern = new String("^PT(?:(\\d+)H)?(?:(\\d+)M)?(?:(\\d+))S?$");

        Pattern r = Pattern.compile(pattern);
        String result;

        Matcher m = r.matcher(youtubetime);
        if (m.find()) {
            String hh = m.group(1);
            String mm = m.group(2);
            String ss = m.group(3);
            mm = mm !=null?mm:"0";
            ss = ss !=null?ss:"0";
            result = String.format("%02d:%02d", Integer.parseInt(mm), Integer.parseInt(ss));

            if (hh != null) {
                result = hh + ":" + result;
            }
        } else {
            result = "00:00";
        }
        return result;
    }
}