Android: getting error near runOnUiThread when i use it near fragment

Question

I am new to Android development and I want to link a button with the animation. I am getting error near runOnUiThread() and getApplication(). When I add this in as an activity it is fine, but when declared in MainFragment it gives error. However when I fix the errors, it creates a method and returns false.

public class MainFragment extends Fragment {


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

    View rootView = inflater.inflate(R.layout.activity_main, container, false);
    ImageButton btnFacebook = (ImageButton)rootView.findViewById(R.id.facebook2);
    final Animation alpha = AnimationUtils.loadAnimation(getActivity(), R.anim.anim_alpha);

    btnFacebook.setOnClickListener(new Button.OnClickListener(){

        @Override
        public void onClick(View arg0) {
            arg0.startAnimation(alpha);

            Thread thread = new Thread()
            {
                @Override               
                public void run()
                {
                    try
                    {
                        Thread.sleep(1000);
                    }catch(InterruptedException e){                         
                    }
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                          startActivity(new Intent(getApplication(),FacebookActivity.class)); 
                        }

                    });
                }
            };


            thread.start();
          }}); 
    return rootView;
}}

In the XML file I only have the facebook imagebutton. When I click that, it has to trigger the animation and then onclick event has to happen, but I don't know why this error is popping up:

The method runOnUiThread(new Runnable(){}) is undefined for the type new Thread(){}

And near getapplication() method The method getApplication() is undefined for the type new Runnable(){}

If I create the two methods the error goes away, but then when I click onto the button it will not go to the facebookActivity.java file.

Can anyone tell/help what should I add to solve this issue. Thanks.

Answer 1

runOnUIThread(...) is a method of Activity.

Therefore, use this:

getActivity().runOnUIThread(...);

But, beware. You're dealing with asynchronous threads, so your Fragment might be detached from its Activity, resulting in getActivity() returning null. You might want to add a check if(isAdded()) or if(getActivity() != null) before executing.

Alternatively, use an AsyncTask, which handles this running on the ui thread by itself.

Answer 2

runOnUiThread(new Runnable(){}) is method in Activity not in the Fragment.

so you need to change

runOnUiThread(new Runnable(){})

into

getActivity().runOnUiThread(new Runnable(){})

For your requrement it is better to use Handler instead of Thread for waiting 1000 milli seconds..