title: Presenter having Handler in Android MVP pattern
body: <p>Is it okay a presenter having Android Handler?<br>
  I know presenters should not have any Android related objects,
  but I really don't have any clear answer.</p>
  
  <p>Here's the thing,
  this presenter runs a disk IO task on another thread,
  meanwhile, the activity has to change its view.</p>
  
  <p>These jobs are supposed to be done concurrently.
  So I decided to pass the activity's handler as an argument 
  and let presenter send message to activity like this:</p>
  
  <pre><code>class FooPresenter: FooContract.Presenter {
      …
      private fun doDiskIOTask(handler: Handler) {
              handler.sendEmptyMessage(0)
          do_something_on_new_thread_and_join()
          handler.sendEmptyMessage(1)
      }
      …
  }
  </code></pre>
  
  <p>The activity has to know when the task is started and finished both and change view.
  Could you tell me if I'm doing it any wrong or the better way?</p>