PrintWriter等待和通知方法做什么？

Question

I read android documentation (which is clear as mud) and it says that:

wait

Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

notify

Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.

Does that mean that:

public synchronized void myAwesomeFunction (PrintWriter out, String[] data)
{
    for (String d : data)
    {
        out.wait();
        out.println (d);
        out.flush();
        out.notify();
    }
}

would wait until PrintWriter finish sending the first string and then move to the next one? or did i get it completely wrong?

Answer 1

Every object in Java can be used as a lock. These methods are inherited from the Object class, and are useful for synchronization between threads. They are completely unrelated to the PrintWriter functionality.

println() is a blocking function - it does not return until it has finished sending the first string (ignoring buffering). Simply writing this:

out.println(d);
System.out.println("'d' has finished writing");

Is all you need to achieve the same effect. Using wait and notify is useful when you want one thread to wait for another, and is not normally useful within the same thread.