Content of Listview not show anythings when using the NavigationDrawer

[monzerahmed6]

I am new in android programming, my project is about getting RSS Feeds from web ,it works fine, then I have moved the app to be in Navigation drawer menu.
Then the application become not working I'm sure there is no error on code but in onActivityCreated() method "I think that !". anyway this my code>>

my Main Activity:

    public class MainActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {
    NavigationView navigationView=null;
    Toolbar toolbar=null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        RssFragment fragment=new RssFragment();
        android.support.v4.app.FragmentTransaction fragmentTransaction=getSupportFragmentManager().beginTransaction();
        fragmentTransaction.replace(R.id.fragment_container,fragment);
        fragmentTransaction.commit();
        toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.addDrawerListener(toggle);
        toggle.syncState();

        navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);
    }

my RssFragment:

    public class RssFragment extends Fragment implements AdapterView.OnItemClickListener {

    private ProgressBar progressBar;
    private ListView listView;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_rss, container, false);
        progressBar = (ProgressBar) view.findViewById(R.id.progressBar);
        listView = (ListView) view.findViewById(R.id.listView);
        listView.setOnItemClickListener(this);
        final SwipeRefreshLayout pullToRefresh = (SwipeRefreshLayout) view.findViewById(R.id.swipe_container);
        pullToRefresh.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
            @Override
            public void onRefresh() {
                startService();
                pullToRefresh.setRefreshing(false);
            }
        });
        return view;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        startService();
    }

    private void startService() {
        Intent intent = new Intent(getActivity(), RssService.class);
        getActivity().startService(intent);
    }

    /**
     * Once the {@link RssService} finishes its task, the result is sent to this BroadcastReceiver
     */
    private BroadcastReceiver resultReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            progressBar.setVisibility(View.GONE);
            List<RssItem> items = (List<RssItem>) intent.getSerializableExtra(RssService.ITEMS);
            if (items != null) {
                RssAdapter adapter = new RssAdapter(getActivity(), items);
                listView.setAdapter(adapter);
            } else {
                Toast.makeText(getActivity(), "An error occurred while downloading the rss feed.",
                        Toast.LENGTH_LONG).show();
            }
        }
    };

    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        RssAdapter adapter = (RssAdapter) parent.getAdapter();
        RssItem item = (RssItem) adapter.getItem(position);
        Uri uri = Uri.parse(item.getLink());
        Intent intent = new Intent(Intent.ACTION_VIEW, uri);
        startActivity(intent);
    }
    @Override
    public void onStart() {
        super.onStart();
        IntentFilter intentFilter = new IntentFilter(RssService.ACTION_RSS_PARSED);
        LocalBroadcastManager.getInstance(getActivity()).registerReceiver(resultReceiver, intentFilter);
    }

    @Override
    public void onStop() {
        super.onStop();
        LocalBroadcastManager.getInstance(getActivity()).unregisterReceiver(resultReceiver);
    }

my app_bar_main :

    <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:id="@+id/fragment_container"
        android:layout_height="match_parent" />

this is was the main activity in the app that call RssFragment before moved to navigition drawer main activity :

    public class MainActivity extends AppCompatActivity {
    @Override   
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        if (savedInstanceState == null) {
            addRssFragment();
        }
    }
    private void addRssFragment() {

        FragmentManager manager = getSupportFragmentManager();
        FragmentTransaction transaction = manager.beginTransaction();
        RssFragment fragment = new RssFragment();
        transaction.add(R.id.fragment_container, fragment);
        transaction.commit();
    }
    }

I really want help with that!!

Note: The application was working well but when I moved it to navigation drawer it did not work and the activity does not show anything,just swipe to refresh widget.