Java Countdownlatch Thread Helper classes

package aaa.bbb;import java.text.simpledateformat;import java.util.date;import  Java.util.concurrent.countdownlatch;public class t1 {final static simpledateformat  sdf = new simpledateformat ("Yyyy-mm-dd hh:mm:ss");p ublic static void  Main (String[] args)  throws exception {countdownlatch countdownlatch = new  countdownlatch (3); Worker w1 = new worker ("W1",  2000, countdownlatch); Worker w2 = new worker ("W2",  5000, countdownlatch); W1.start ();//w2.start ();// Countdownlatch.await ();//  waits for all workers to complete the work System.out.println ("all work done at "  +  sdf.format (New date ()));} static class worker extends thread {string workername;int worktime; Countdownlatch latch;public worker (string workername, int worktime,  Countdownlatch laTCH)  {this.workerName = workerName;this.workTime = workTime;this.latch =  latch;} @Overridepublic  void run ()  {system.out.println ("worker "  + workername +   " do work begin at " + sdf.format (New date ())); Try {thread.sleep ( Worktime);}  catch  (interruptedexception e)  {e.printstacktrace ();} System.out.println ("worker "  + workerName +  " do work complete at   "+ sdf.format (New date ())); Latch.countdown ();//  Worker completes work, counter minus one}}}

Java Countdownlatch Thread Helper classes