jb11.0 threads tick tock, Java

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//'main' method must be in a class 'Rextester'.
//Compiler version 1.8.0_111

import java.util.*;
import java.lang.*;

class Rextester
{  
    public static void main(String args[])
    {
        System.out.println("Hello, World!\n");
        
        Clock cl = new Clock(true);
        ClockWork cw1 = ClockWork.createWork(cl, Clock.ClockState.TICK);
        ClockWork cw2 = ClockWork.createWork(cl, Clock.ClockState.TOCK);

try{
            Thread.sleep(2);
            System.out.println("\n before stop ");
            cl.stop();
            
            cw1.getThread().join();
            System.out.println("\n cw1 stoped ");
            cw2.getThread().join();
            System.out.println("\n cw2 stoped ");
        }catch(InterruptedException e){
            System.out.println(e);
        }
        System.out.println("\n after stop ");
    }
}

class ClockWork implements Runnable{
    private Clock _clock;
    private Clock.ClockState _workState;
    private Thread _th;
    
    private ClockWork(Clock clock, Clock.ClockState workState){
        _clock = clock;
        _workState = workState;
        _th = new Thread(this);
        _th.setPriority(Thread.MAX_PRIORITY);
    }
    
    public static ClockWork createWork(Clock clock, Clock.ClockState clockState){
        ClockWork cw = new ClockWork(clock, clockState);
        cw._th.start();
        return cw;
    }
    
    public Thread getThread(){
        return _th;
    }
    
    public void run(){
        while(_clock.isRun()){
            if(_workState == Clock.ClockState.TICK){
                _clock.tick();
            }else if(_workState == Clock.ClockState.TOCK){
                _clock.tock();
            }
        }
    }
}

class Clock{
    
    public enum ClockState{
        TICK, TOCK;
    }
        
    ClockState _curState;
    boolean _run;
   
    public synchronized void tick(){
        _curState = ClockState.TICK;
        System.out.print(_curState);
         
        notify();
        if(!_run) return;
        while(_curState == ClockState.TICK){
            try{
                wait();
            }catch(InterruptedException e){
                System.out.println(e);
            }
       }
    }
    
    public synchronized void tock(){
        _curState = ClockState.TOCK;
        System.out.println(" " + _curState);
        
        notify();
        if(!_run) return;
        while(_curState == ClockState.TOCK){
            try{
                wait();
            }catch(InterruptedException e){
                System.out.println(e);
            }
        }
    }
    
    Clock(boolean run){
        _run = run;        
    }
    
    public void stop(){
        _run = false;
    }
    
    public boolean isRun(){
        return _run;
    }
    
    public Clock.ClockState getState(){
        return _curState;
    }
}

[ + ] Show input
Compilation time: 0.73 sec, absolute running time: 10.05 sec, cpu time: 0 sec, memory peak: 0 Mb, absolute service time: 10,79 sec