Sequential run of threads

Thread t1 = new Thread( new MyRunnable( ) );
Thread t2 = new Thread( new MyRunnable( t1 ) );
Thread t3 = new Thread( new MyRunnable( t2 ) );
t1.start();
t2.start();
t3.start();

...

class MyRunnable()
{
   private Thread mustFinishFirst;
   public MyRunnable()
   {}
   public MyRunnable( Thread mustFinishFirst )
   {
      this.mustFinishFirst = mustFinishFirst;
   }
   public void run()
   {
      if( mustFinishFirst != null )
         mustFinishFirst.join()
      ...
   }
}