从 Activity 按下返回后，在 Fragment 中重新加载 ListView

Question

i have a Fragment that load a ListView from a database and it is a Favorite list which user choosed before, when you click on the list item it starts an Activity and user will be able to see the detail and unfavorite the item the problem is when the user unfavorite an item and press back to back to fragment of fave list the view is still shows the first lodaded listview not the updated one. i want to know how the life cycle of fragment will work when you start an activity and come back again to know where to implement my

adapter.notifyDataSetChanged()

Im using GoogleApiClient to get the location of user so i use to load the database in my onConnected methode:

    @Override
public void onConnected(@Nullable Bundle bundle) {

    LocationServices.FusedLocationApi.requestLocationUpdates(
            mLocationClient, mLocationRequest, this);

    if (    ContextCompat.checkSelfPermission(getContext(), android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED
            && ContextCompat.checkSelfPermission(getContext(), Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        // You need to ask the user to enable the permissions
    } else {
        LocationTracker tracker = new LocationTracker(getContext()) {
            @Override
            public void onLocationFound(@NonNull Location location) {
                currentLocation = location;
            }
            @Override
            public void onTimeout() {
            }
        };
        tracker.startListening();
    }
    if (currentLocation ==null) {
        currentLocation = LocationServices.FusedLocationApi.getLastLocation(mLocationClient);
    }

    if (ContextCompat.checkSelfPermission(getActivity(), android.Manifest.permission.ACCESS_COARSE_LOCATION)
            != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(getActivity(), new String[]{android.Manifest.permission.ACCESS_COARSE_LOCATION},
                PERMISSION_ACCESS_COARSE_LOCATION);
    }
    if (currentLocation != null) {
        //Loading LAT LOng of //arkers on map
        for(int i=0; i<storedfavoritesitem.size(); i++) {
            FavoriteModel Faveitem = storedfavoritesitem.get(i);
            String locality = Faveitem.name;
            int id = Faveitem.id;
            double lat = Faveitem.lat;
            double lon =  Faveitem.lon;
            Location location = new Location("Beach");
            location.setLatitude(lat);
            location.setLongitude(lon);
            float distance = currentLocation.distanceTo(location);
            mResualt.add(new SearchResualtClass(id, distance / 1000, locality));
        }
        Comparator<SearchResualtClass > comperator = new Comparator<SearchResualtClass>()
        {
            @Override
            public int compare(SearchResualtClass  object1, SearchResualtClass  object2) {
                float First = object1.getDistance();
                float Second = object2.getDistance();
                return (First < Second ? -1 : (First == Second ? 0 : 1));
            }
        };
        Collections.sort(mResualt, comperator);
        adapter = new CustomAdapterSearch(getActivity().getApplicationContext(),mResualt);
        exList.setAdapter(adapter);
        adapter.notifyDataSetChanged();
    }

    exList.setOnItemClickListener(new AdapterView.OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position,
                                long id) {
            Intent intent = new Intent(view.getContext(), FragmentBeach.class);
            intent.putExtra("array", jsonArray.toString());
            SearchResualtClass item = (SearchResualtClass) parent.getItemAtPosition(position);
            intent.putExtra("id", item.getId());
            startActivity(intent);
        }
    });
}

Answer 1

Move your code that loaded the datalist and feed it to adapter from onCreate() to onResume()

This will ensure your list will be reloaded whenever your fragment goes through pause-resume phase.

And as far as lifecycle is concerned, do read [Fragment Lifecycles][**1]

Update : You will have to update storedfavoritesitem then run following piece of code

if (currentLocation != null) {
        //Loading LAT LOng of //arkers on map
        for(int i=0; i<storedfavoritesitem.size(); i++) {
            FavoriteModel Faveitem = storedfavoritesitem.get(i);
            String locality = Faveitem.name;
            int id = Faveitem.id;
            double lat = Faveitem.lat;
            double lon =  Faveitem.lon;
            Location location = new Location("Beach");
            location.setLatitude(lat);
            location.setLongitude(lon);
            float distance = currentLocation.distanceTo(location);
            mResualt.add(new SearchResualtClass(id, distance / 1000, locality));
        }
        Comparator<SearchResualtClass > comperator = new Comparator<SearchResualtClass>()
        {
            @Override
            public int compare(SearchResualtClass  object1, SearchResualtClass  object2) {
                float First = object1.getDistance();
                float Second = object2.getDistance();
                return (First < Second ? -1 : (First == Second ? 0 : 1));
            }
        };
        Collections.sort(mResualt, comperator);
     if(adapter == null){
        adapter = new CustomAdapterSearch(getActivity().getApplicationContext(),mResualt);
        exList.setAdapter(adapter);
    }else{
        adapter.notifyDataSetChanged();
    }

Answer 2

adapter.notifyDataSetChanged() will surely work. You have to call activity using startActivityForResult method and pass resultCode before your called activity is finished. Based on this resultCode, you can call adapter.notifyDataSetChanged(). Here is sample code. Pls replace accordingly.

startActivityForResult(intent, requestCode);

public void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (resultCode == 1) {
        adapter.notifyDataSetChanged();
    }
}

Answer 3

Ok i solved it, i was notifyDataSetChanged but actually everything was loading from database so after i made change i should reload the list again from database and send the change notify so i implement the follwing code inside OnResume

 @Override
public void onResume() {
    super.onResume();
    storedfavoritesitem = FavoriteModel.getAllFavorites();
    if (adapter!=null && currentLocation!=null) {
        mResualt.clear();
        for (int i = 0; i < storedfavoritesitem.size(); i++) {
            FavoriteModel Faveitem = storedfavoritesitem.get(i);
            String locality = Faveitem.name;
            int id = Faveitem.id;
            double lat = Faveitem.lat;
            double lon = Faveitem.lon;
            Location location = new Location("Beach");
            location.setLatitude(lat);
            location.setLongitude(lon);
            float distance = currentLocation.distanceTo(location);
            mResualt.add(new SearchResualtClass(id, distance / 1000, locality));
        }
        adapter.notifyDataSetChanged();
    }
  }
}

and it works fine now thanks every one