AsyncTask not updating UI when Fragment is resumed

Question

I have a "HomeFragment" class which extends Fragment. Everything is working fine fragment is created for the first time. But when I switch to some other fragment and come back to this, the UI does not get updated. In fact it shows nothing in that TextSwitcher. I checked using Log.d that ChangeText thread is running in background all the time. Where is the mistake ?

public class HomeFragment extends Fragment {

    private TextSwitcher mSwitcher;
    String textToShow[]={"Main HeadLine","Your Message"};
    int messageCount=textToShow.length;
    int currentIndex=-1;
    private Handler myHandler;
    ChangeText CT;

    public HomeFragment(){}

    @SuppressLint("HandlerLeak")
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {

        View rootView = inflater.inflate(R.layout.fragment_home, container, false);

        mSwitcher = (TextSwitcher) rootView.findViewById(R.id.textSwitcher);
        mSwitcher.setFactory(new ViewFactory() {

            public View makeView() {
                // TODO Auto-generated method stub
                TextView myText = new TextView(getActivity());
                myText.setGravity(Gravity.TOP | Gravity.CENTER_HORIZONTAL);
                myText.setTextSize(36);
                myText.setTextColor(Color.BLUE);
                return myText;
            }
        });

// Declare the in and out animations and initialize them  
Animation in = AnimationUtils.loadAnimation(getActivity(),android.R.anim.slide_in_left);
Animation out = AnimationUtils.loadAnimation(getActivity(),android.R.anim.slide_out_right);
        mSwitcher.setInAnimation(in);
        mSwitcher.setOutAnimation(out);


        myHandler = new Handler() {
            public void handleMessage(Message msg) {
                doUpdate();
            }
        };




        CT = new ChangeText();
        CT.execute();

        return rootView;
    }

class ChangeText extends AsyncTask<String, String, String> {

        @Override
        protected String doInBackground(String... f_url) {
            try {

                while(true)
                {
                    if (isCancelled())  break;
                    myHandler.sendEmptyMessage(currentIndex);
                    SystemClock.sleep(1500);
                }


            } catch (Exception e) {
                Log.e("VIVEK: ", e.getMessage());
            }

            return null;
        }

    }

private void doUpdate() {
        currentIndex++;
        if(currentIndex==messageCount)
        {
            currentIndex=0;
        }
        Log.d("VIVEK", textToShow[currentIndex]);
        mSwitcher.setText(textToShow[currentIndex]);
    }
}

add onPostExecute() method in asynctask and call in it doUpdate() — Darko Rodic, Jan 23 '14 at 11:00
call doUpdate() I guess, if that method is updating fragment, havent really read all code :D check the example: http://stackoverflow.com/questions/9671546/asynctask-android-example?rq=1 — Darko Rodic, Jan 23 '14 at 11:03
I think that will not work. onPostExecute() is called when background process is complete. But I am using infinite loop. So it will never be called. — gomchikbhoka, Jan 23 '14 at 11:05

score 0 · Accepted Answer · edited May 23 '17 at 12:11

0

you should use asynctask for that, try using handler with other thread here is an example: Change View from other thread

also other nice example: http://androidexample.com/Thread_With_Handlers_-_Android_Example/index.php?view=article_discription&aid=58&aaid=83

hope it helps, regards

edited May 23 '17 at 12:11

Community

1
1

answered Jan 23 '14 at 11:08

Darko Rodic

1,010
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score 0 · Answer 2 · answered Jan 23 '14 at 11:28

0

First, I strongly suggest you take a look at CountDownTimer class. I think it will fit more in your use case. Second, try moving these:

CT = new ChangeText();
CT.execute();

to fragment's onResume() and see if it solves your problem.

answered Jan 23 '14 at 11:28

M.Sameer

3,072
1
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37

AsyncTask not updating UI when Fragment is resumed

2 Answers2