如何允许两个线程在android中以预定义的顺序执行？

Question

我有多个处理程序（线程）执行，一些线程依赖于其他的结果..所以我想让线程以定义的顺序执行

Answer 1

You can start the second thread from the first thread.

final Thread th2 = new Thread(new Runnable(){
    public void run(){
        doSomething2;
    }
}
Thread th1 = new Thread(new Runnable(){
    public void run(){
        doSomething;
        th2.start();
    }
});
th1.start();
th2.join();

But you most probably don't need the second thread at all:

Thread th1 = new Thread(new Runnable(){
    public void run(){
        doSomething;
        doSomething2;
    }
});
th1.start();
th1.join();

Answer 2

If you have to wait in one thread for another thread to complete, there are several options.

One is to use a CountdownLatch,

Somewhere common share the latch CountdownLatch latch = new CountdownLatch(1);

Thread 1,

 doSomething();
 countdownLatch.countdown();

Thread 2,

 countdownLatch.await();
 doSomethingElse();

Countdown latches can only be used once though.

There are a bunch of other classes in java.util.concurrent that may solve your problem. LinkedBlockingQueue, CyclicBarrier, Exchanger may be useful. Its hard to say more without knowing more details.

And as the comment and other answer pointed out, if you can, just avoid multiple threads altogether.