Test join method

class Sync implements Runnable{
  private Thread monitor;
  public  Sync setMonitor(Thread mon){
      monitor = mon;
      return this;
  }

  public void run() {
    try {
        System.out.println(Thread.currentThread().getName() + ": start");
        if (monitor == null)
            Thread.sleep(1000);
        else
            monitor.join(); //ожидание выполнения потока monitor
        System.out.println(Thread.currentThread().getName() + ": end");
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
  }
}

public class TestJoinMethod{
  public static void main(String[] args) throws Exception{
    Thread ta = new Thread(new Sync(), "threadA");
    Thread tb = new Thread(new Sync().setMonitor(ta), "threadB");
    ta.start();
    tb.start();
    try {
        tb.join(); //ожидание выполнения потока tb
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    System.out.println(Thread.currentThread().getName() + ": end");
 }
}