HandlerThread and Handler: how to use AudioRecord.setRecordPositionUpdateListener?

Question

I'm confused by Handler and HandlerThread classes usage. The reason I'm trying to use them is I want to utilize AudioRecord class and its setRecordPositionUpdateListener method (reference). The methos description says:

Use this method to receive AudioRecord events in the Handler associated with another thread than the one in which you created the AudioTrack instance.

And that's exactly what I want - to setup the AudioRecord in the main thread, but receive data in a working thread. I figure I need a HandlerThread so I've created and started one. I've also defined a callback method that implements AudioRecord.OnRecordPositionUpdateListener interface. I want this callback to be called from the worker HandlerThread. What I don't understand now is how to create the Handler to pass to setRecordPositionUpdateListener.

Answer 1

To associate Handler with a certain thread, you should create it by passing corresponding Looper in its constructor. So, if you already have a HandlerThread it can be done in the following way:

Looper looper = myHandlerThread.getLooper();
Handler handler = new Handler(looper);

And that's it, just use this handler in setRecordPositionUpdateListener method and callback will be executed at the worker thread. If you need more explanation on Handler, Looper and HandlerThread, you can take a look here.