Question

I have a MainActivity and an AsyncTask MyTask. They are separate classes. In MyTask, I want to update a TextView in MainActivity.

This seems easy if MyTask in a inner class of MainActivity because I can just call findViewById(). But now these two classes are separate.

So in my MainActivity I do this:

MyTask myTask=new MyTask();
Context context=this.getApplicationContext();
myTask.execute(context);

And my task is like this:

public class MyTask extends AsyncTask<Context, Void, Void>
{
    TextView mText;
    protected Void doInBackground(Context... params) {
        Context context=params[0];
        mText = (TextView) ((MainActivity)context).findViewById(R.id.text);
...
    }
}

I know the “mText = (TextView) ((MainActivity)context).findViewById(R.id.text);” is wrong but I haven’t found the solution.

Any Hints

Thanks in Advance

Answer 1

You can do something like this. You can ignore the WeakReference if the task won’t be long living:

public class MyTask extends AsyncTask<Void, Void, Void> {
  private WeakReference<MainActivity> mActivity;
  public MyTask(MainActivity activity) {
    mActivity = new WeakReference<MainActivity>(activity);
  }

  public void onPostExecute(Void result) {
    MainActivity activity = mActivity.get();
    if (activity != null) {
      TextView text = activity.findViewById(R.id.text);
    }
  }
}