Android处理程序，计时器和多线程

Question

I am basically doing the code post at the bottom of this message. foobar() posts an event into a common state machine. I also have touchscreen events posted into the common state machine. Is it true, that by using a handler I have no synchronization issues? (ie, my state machine won't be message up by a touch even and a foobar event) at the same time?

private Handler handler = new Handler();
handler.postDelayed(runnable, 100);


private Runnable runnable = new Runnable() {
   @Override
   public void run() {
      /* do what you need to do */
      foobar();
      /* and here comes the "trick" */
      handler.postDelayed(this, 100);
   }
};

Answer 1

The same instance of Handler object will process through the queue of messages/runnables passed to it on the Looper of choice (main thread by default).

So NO, if you send a list of messages to the Handler they will be run through 1 at a time never in parallel.

BUT if you are concerned about synchronization issues you should synchronize(object) {} your code inside your methods around a common object, that way they will wait for lock on that common object meaning that you could call that method from anywhere and it would never run in parallel with any other code using synchronize(object) {} .