从片段更新UI

Question

I have a fragment that gets data from a DialogFragment via intent with onActivityResult(...);

I am trying to update the fragment's UI but runOnUiThread does not work.

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    ArrayList<Farm> farms = data.getParcelableArrayListExtra("farms_list");
    float totalArea = 0;
    for(Farm farm : farms) {
        if (farm.isSelected()) {
            Log.d("farm", farm.getName());
            totalArea += farm.getArea();
        }
    }
    final float finalTotalArea = totalArea;
    activity.runOnUiThread(new Runnable() {
        @Override
        public void run() {
            area.setText(String.valueOf(finalTotalArea));
        }
    });
}

The area TextView does not update.

I get the reference to the activity with onAttach() method.

@Override
public void onAttach(Context context) {
    super.onAttach(context);
    if (!(context instanceof PageFragmentCallbacks)) {
        throw new ClassCastException(
                "Activity must implement PageFragmentCallbacks");
    }

    mCallbacks = (PageFragmentCallbacks) context;
    this.activity = (Activity) context;
}

Answer 1

onActivityResult is being called on main thread. More here . For some reason views can't be edited from this method (probably not created or drawn). One trick that you can do is set var boolean updateTextView = false; On onActivityResult set it on true, save data that you got, and than onResume check updateTextView and if true set data to your TextView.

Answer 2

What about trying to wrap it in a proper thread that you launch afterwards?

new Thread() {
            public void run() {
                try {
                   activity.runOnUiThread(new Runnable() {
                       @Override
                       public void run() {
                          area.setText(String.valueOf(finalTotalArea));
                       }
                   });
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }.start();

Answer 3

Seems like your Activity is loosing your Fragment somewhere, what I did in this case was to add a Method to my Callbacks , maybe reattachDialog(DialogFragment dialogFragment) and calling it in onResume of the DialogFragment with reattachDialog(this) .

And in your Activity you do this:

@Override
public void reattachFragment(DialogFragment dialogFragment) {
 this.dialogFragment = dialogFragment;
}

Or in Fragment:

@Override
public void reattachFragment(DialogFragment dialogFragment) {
 getActivity().setDialog(dialogFragment);
}