public class TestThread {

    public static void main(String[] args) {
        Thread t1 = new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println("t1");
            }
        });
        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();
    }

}

调用的顺序是t3/t2/t1，结果是