现在有T1、T2、T3三个线程，怎样保证T2在T1执行完后执行，T3在T2执行完后执行

public class TestJoin
{
public static void main(String[] args)
{
Thread t1 = new MyThread(“线程1”);
Thread t2 = new MyThread(“线程2”);
Thread t3 = new MyThread(“线程3”);

    try
    {
        //t1先启动
        t1.start();
        t1.join();
        //t2
        t2.start();
        t2.join();
        //t3
        t3.start();
        t3.join();
    }
    catch (InterruptedException e)
    {
        e.printStackTrace();
    }
}

}

class MyThread extend Thread{
public MyThread(String name){
setName(name);
}
@Override
public void run()
{
for (int i = 0; i < 5; i++)
{
System.out.println(Thread.currentThread().getName()+": "+i);
try
{
Thread.sleep(100);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
}
}
}

还有一种方式，在t3开始前join t2，在t2开始前join t1
public class TestJoin2
{
public static void main(String[] args)
{
final Thread t1 = new Thread(new Runnable() {

        @Override
        public void run() {
            System.out.println("t1");
        }
    });
    final Thread t2 = new Thread(new Runnable() {

        @Override
        public void run() {
            try {
                //引用t1线程，等待t1线程执行完
                t1.join();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("t2");
        }
    });
    Thread t3 = new Thread(new Runnable() {

        @Override
        public void run() {
            try {
                //引用t2线程，等待t2线程执行完
                t2.join();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("t3");
        }
    });
    t3.start();
    t2.start();
    t1.start();
}

}