class HandlerThreadActivity : AppCompatActivity() {

//work to do by requestHandler

val runnable = Runnable {

//some background job

responseHandler.sendMessage(Message()) //send message or post the job

responseHandler.post {

//some UI action

}

}

//handler on the main thread, override handleMessage if needed

val responseHandler = object: Handler(Looper.getMainLooper()) {

override fun handleMessage(msg: Message?) {

super.handleMessage(msg)

//some action on UI

}

}

//handler on the background thread of handlerThread object

lateinit var requestHandler: Handler

//instead of Thread use reusable HandlerThread

//this can be also done by extend HandlerThread class and putting there Handler object

val handlerThread = HandlerThread("HandlerThread")

override fun onCreate(savedInstanceState: Bundle?) {

super.onCreate(savedInstanceState)

setContentView(R.layout.activity_handler_thread)

handlerThread.start() //start the thread

requestHandler = Handler(handlerThread.looper) //now Looper of handlerThread can be passed

button.setOnClickListener {

requestHandler.post(runnable) //post the job to MessageQueue

}

}

override fun onDestroy() {

super.onDestroy()

//remove tasks and messages from handlers

requestHandler.removeCallbacksAndMessages(null)

responseHandler.removeCallbacksAndMessages(null)

handlerThread.quitSafely() //quit HandlerThread's Looper

handlerThread.interrupt() //stop current job

}

}