ThreadGroup tg=new ThreadGroup("新线程组名");
Thread t=new Thread(tg,new Runnable(){},"线程名");;
Thread t2=new Thread(tg,new Runnable(){},"线程名2");;

System.out.println(t.getThreadGroup().getName());


线程组作用,可以对整个组进行操作,例如
tg.setDaemon(true); //对整个线程组的线程设置守护线程