我如何加入两个线程？

Question

当我加入一个线程时，第一个线程需要先运行，然后第二个thrads运行是否正确？如果是这样，我如何加入Main方法中的两个线程？

public class SynchronizedThreads implements Runnable {
    Thread t;

    public SynchronizedThreads() {
        t = new Thread(this, "Synched Thread");
        t.start();
    }
    public void run() {
        for(int i = 0; i < 100; i++) {
            System.out.println(i);
            try {
                t.sleep(1000);
            } 
            catch (InterruptedException e) {
                e.printStackTrace();
            }
        }   
    }
}

public class StartSynchronizedThreads {
    public static void main(String[] args) {
        SynchronizedThreads x = new SynchronizedThreads();
        SynchronizedThreads y = new SynchronizedThreads();  
    }
}

Answer 1

try {
    x.t.join();
    y.t.join();
} catch (InterruptedException e) {
    System.out.println("Main thread Interrupted");
}