Thread t = new Thread(){
                public void run(){
                    Thread th1 = new Thread();
                    Thread th2 = new Thread();
                    Thread th3 = new Thread();
                    Thread th4 = new Thread();
                    
                    //这四个线程分别运行5秒
                    
                    try {
                        th1.start();
                        th1.join();
                        
                        th2.start();
                        th2.join();
                        
                        th3.start();
                        th3.join();
                        
                        th4.start();
                        th4.join();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            };
            t.start();