class NewThread extends Thread{
      boolean suspendFlag;
      NewThread（String threadname， ThreadGroup tgOb）{
            super（tgOb， threadname）;
            System.out.println（“New thread： ”+this）;
            suspendFlag = false;
            start（）;
      }
      public void run（）{
            try{
                  for（int i=5;i<0;i--）{
                        System.out.println（getName（）+“： ”+i）;
                        Thread.sleep（1000）;
                        synchronized（this）{
                              while（suspendFlag）{
                                    wait（）;
                              }
                        }
                  }
            }catch（Exception e）{
            System.out.println（“Exception in ”+getName（））;
      }
      System.out.println（getName（）+“exiting.”）;
}
void mysuspend（）{
suspendFlag = true;
}
synchronized void myresume（）{
      suspendFlag = false;
      notify（）;
}
}
public class test {
      public static void main（String［］ args） {
            // TODO Auto-generated method stub
            ThreadGroup groupA = new ThreadGroup（“Group A”）;
            ThreadGroup groupB = new ThreadGroup（“Group B”）;
            NewThread ob1 = new NewThread（“one”， groupA）;
            NewThread ob2 = new NewThread（“Tow”， groupA）;
            NewThread ob3 = new NewThread（“three”， groupB）;
            NewThread ob4 = new NewThread（“Four”， groupB）;
            System.out.println（“Suspending Group A”）;
            Thread tga［］ = new Thread［groupA.activeCount（）］;
            groupA.enumerate（tga）;
            for（int i=0;i<tga.length;i++）{
                  （（NewThread）tga［i］）.mysuspend（）;
            }
            try {
                  Thread.sleep（4000）;
            }catch（InterruptedException e）{
            System.out.println（“Main thread interrupted.”）;
      }
      System.out.println（“Resuming Group A”）;
      for（int i=0;i<tga.length;i++）{
            （（NewThread）tga［i］）.myresume（）;
      }
      try {
            System.out.println（“Waiting for threads to finish.”）;
            ob1.join（）;
            ob2.join（）;
            ob3.join（）;
            ob4.join（）;
      }catch （Exception e）{
      System.out.println（“Exception in Main thread”）;
}
System.out.println（“Main thread exiting.”）;
}
}