Android MessageQueue Mechanism

Android MessageQueue Mechanism

Core classes:

Handler – the operator, user apps use this to operate the Messages: send messagewith postRunnable, sendMessage etc. and process Messages in handleMessage.

Message – the container for the data andinformation

MessageQueue – the internal containers forMessages. User apps are not allowed to operate it directly. It is operatedinternally by Handler

Looper – the rules which let thread rununtil stop() is called. This is much like use a while (true) in the thread tomake it run as long as you wish

The general Message processing would be like this:

1. make the thread (either main thread or user-created thread) can loop,with calling Looper.prepare();

2. Send the Message with Handler.

3. OverrideHandler.handleMessage to process the Message;

4. Stop the looper by callingLooper.stop(), then thread will exit.