I create simple Android application and I try to use MVP design pattern. I read some tutorials and after that I started writing code. Now I have simple activity with its functionality and my code looks like this.

View:

interface TimerView {     fun updateTime(time: Long)     fun disableStop()     fun disableStart()     fun disablePause()     fun enableStop()     fun enableStart()     fun enablePause() }  class MainActivity : AppCompatActivity(), TimerView {     private var presenter = TimerPresenter(this)      override fun onCreate(savedInstanceState: Bundle?) {         super.onCreate(savedInstanceState)         setContentView(R.layout.activity_main)         setSupportActionBar(toolbar)     }      override fun onResume() {         super.onResume()         presenter.restoreState(this)     }      override fun onPause() {         super.onPause()         presenter.saveState(this)         presenter.stopTimer()     }      fun stopTimer(view: View) {         presenter.stopTimer()         presenter.resetTimer()     }      fun startTimer(view: View) {         presenter.startTimer()     }      fun pauseTimer(view: View) {         presenter.pauseTimer()     }      override fun updateTime(time: Long) {         timeText.text = timeToString(time)     }      override fun disableStop() {         stopFab.isEnabled = false     }      override fun disableStart() {         startFab.isEnabled = false     }      override fun disablePause() {         pauseFab.isEnabled = false     }      override fun enableStop() {         stopFab.isEnabled = true     }      override fun enableStart() {         startFab.isEnabled = true     }      override fun enablePause() {         pauseFab.isEnabled = true     } } 

Presenter:

class TimerPresenter(private val view: TimerView) : TimerListener {     private val timer = Timer(this)      fun stopTimer() {         timer.stop()     }      fun startTimer() {         timer.start()     }      fun pauseTimer() {         timer.pause()     }      fun resetTimer() {         timer.reset()     }      fun saveState(context: Context) {         timer.saveState(context)     }      fun restoreState(context: Context) {         timer.restoreState(context)     }      private fun setStopView() {         view.disableStop()         view.disablePause()         view.enableStart()     }      private fun setStartView() {         view.disableStart()         view.enableStop()         view.enablePause()     }      private fun setPauseView() {         view.disablePause()         view.enableStop()         view.enableStart()     }      private fun setViewState(state: TimerData.State) {         when (state) {             TimerData.State.Stop -> setStopView()             TimerData.State.Run -> setStartView()             TimerData.State.Pause -> setPauseView()         }     }      private fun updateTimer(timeRemaining: Long) {         view.updateTime(timeRemaining)     }      override fun onTimerFinish() {         timer.reset()     }      override fun onTimerTick(timeRemaining: Long) {         updateTimer(timeRemaining)     }      override fun onTimerStateChange(newState: TimerData.State) {         setViewState(newState)     }      override fun onTimerReset(timeRemaining: Long) {         updateTimer(timeRemaining)     }      override fun onTimerStateRestored(timeRemaining: Long, state: TimerData.State) {         updateTimer(timeRemaining)         setViewState(state)         if (state == TimerData.State.Run) {             timer.start()         }     } } 

Model:

interface TimerListener {     fun onTimerFinish()     fun onTimerTick(timeRemaining: Long)     fun onTimerStateChange(state: TimerData.State)     fun onTimerReset(timeRemaining: Long)     fun onTimerStateRestored(timeRemaining: Long, state: TimerData.State) }  data class TimerData(var state: State = State.Stop,                      var timerLength: Long = 0L,                      var timeRemaining: Long = 0L) {     enum class State {         Stop,         Run,         Pause     }      fun loadData(context: Context) {         state = PrefUtils.getState(context)         timerLength = PrefUtils.getTimerLength(context)         timeRemaining = if (state != State.Stop) {             PrefUtils.getTimeRemaining(context)         } else {             timerLength         }     }      fun saveData(context: Context) {         PrefUtils.setState(context, state)         PrefUtils.setTimeRemaining(context, timerLength)         PrefUtils.setTimeToStop(context, timeRemaining)     }      fun reset() {         timeRemaining = timerLength     } }  class Timer(private val listener: TimerListener) {     private var data = TimerData()     private var timer: CountDownTimer? = null      fun start() {         timer = object : CountDownTimer(data.timeRemaining * 1000L, 1000L) {             override fun onFinish() {                 stop()                 listener.onTimerFinish()             }              override fun onTick(millisUntilFinished: Long) {                 --data.timeRemaining                 listener.onTimerTick(data.timeRemaining)             }         }.start()         data.state = TimerData.State.Run         listener.onTimerStateChange(data.state)     }      fun stop() {         timer?.cancel()         data.state = TimerData.State.Stop         listener.onTimerStateChange(data.state)     }      fun pause() {         timer?.cancel()         data.state = TimerData.State.Pause         listener.onTimerStateChange(data.state)     }      fun reset() {         data.reset()         listener.onTimerReset(data.timeRemaining)     }      fun saveState(context: Context) {         data.saveData(context)     }      fun restoreState(context: Context) {         data.loadData(context)         listener.onTimerStateRestored(data.timeRemaining, data.state)     } } 

Did I separate tasks correctly between classes or maybe there is something wrong with my code?