android – 片段没有附加到上下文

@Override
public boolean onoptionsItemSelected(MenuItem item) {
    switch (item.getItemId()){
        case  R.id.menu_sort:
            ListFragment listFragment = new ListFragment();
            listFragment.sortByPopularity();
            break;
    }
    return super.onoptionsItemSelected(item);
}

片段代码.我没有附加活动时发现错误.但没有任何背景

public class ListFragment extends Fragment implements listadapter.ItemClickListener {

    /**
     * Needed
     */
    RecyclerView recyclerView;
    View view;
    List<BasePojo.Result> list;
    listadapter listadapter;

    public ListFragment() {
    }

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

        /**
         * Main Initialization
         */
        view = inflater.inflate(R.layout.fragment_list,container,false);
        recyclerView = view.findViewById(R.id.recycler_list_detailed);
        recyclerView.setLayoutManager(new GridLayoutManager(getActivity(),2));
        list = new ArrayList<>();
        listadapter = new listadapter(list,setonItemClickCallback());
        recyclerView.setAdapter(listadapter);

        RetrofitClient.getApiService().getPhotosList(getString(R.string.api_key)).enqueue(new Callback<BasePojo>() {
            @Override
            public void onResponse(Call<BasePojo> call,Response<BasePojo> response) {
                BasePojo basePojo = response.body();
                list.addAll(basePojo.getResults());
                recyclerView.getAdapter().notifyDataSetChanged();
            }

            @Override
            public void onFailure(Call<BasePojo> call,Throwable t) {
                Log.d("tag","Response Failed" + t.toString());

            }
        });


        return view;
    }

    @Override
    public void onItemClick(View view,int position) {
        Log.v("in on click","value " + position);

    }

    private OnItemClickListener.OnItemClickCallback setonItemClickCallback() {
        OnItemClickListener.OnItemClickCallback onItemClickCallback = new OnItemClickListener.OnItemClickCallback() {
            @Override
            public void onItemClicked(View view,int position) {
                BasePojo.Result itemClicked = list.get(position);
                Bundle bundle = new Bundle();
                bundle.putString("title",itemClicked.getoriginalTitle());
                bundle.putString("overview",itemClicked.getoverview());
                bundle.putString("release_date",itemClicked.getReleaseDate());
                bundle.putString("Vote_average",itemClicked.getVoteAverage().toString());
                bundle.putString("poster_path",itemClicked.getPosterPath());
                DetailedFragment detailedFragment = new DetailedFragment();
                detailedFragment.setArguments(bundle);
                FragmentManager manager = getActivity().getSupportFragmentManager();
                FragmentTransaction transaction = manager.beginTransaction();
                transaction.replace(R.id.main_frame_list,detailedFragment);
                Log.d("tag","title is 111 " + bundle.get("title"));

                transaction.commit();
            }

        };
        return onItemClickCallback;
    }

    @Override
    public void onAttachFragment(Fragment childFragment) {
        super.onAttachFragment(childFragment);

    }

    public void sortByPopularity() {
        RetrofitClient.getApiService().getPopularList(getString(R.string.api_key)).enqueue(new Callback<BasePojo>() {
            @Override
            public void onResponse(Call<BasePojo> call,"Response Failed" + t.toString());

            }
        }); }

}

这是一个错误

05-09 12:48:26.915 5775-5775/com.borisruzanov.popularmovies E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.borisruzanov.popularmovies,PID: 5775
java.lang.IllegalStateException: Fragment ListFragment{6dbd6de} not attached to a context.
    at android.support.v4.app.Fragment.requireContext(Fragment.java:614)
    at android.support.v4.app.Fragment.getResources(Fragment.java:678)
    at android.support.v4.app.Fragment.getString(Fragment.java:700)
    at com.borisruzanov.popularmovies.ListFragment.sortByPopularity(ListFragment.java:110)
    at com.borisruzanov.popularmovies.MainActivity.onoptionsItemSelected(MainActivity.java:47)
    at android.app.Activity.onMenuItemSelected(Activity.java:3204)
    at android.support.v4.app.FragmentActivity.onMenuItemSelected(FragmentActivity.java:407)
    at android.support.v7.app.AppCompatActivity.onMenuItemSelected(AppCompatActivity.java:195)
    at android.support.v7.view.WindowCallbackWrapper.onMenuItemSelected(WindowCallbackWrapper.java:108)
    at android.support.v7.view.WindowCallbackWrapper.onMenuItemSelected(WindowCallbackWrapper.java:108)
    at android.support.v7.app.ToolbaractionBar$2.onMenuItemClick(ToolbaractionBar.java:63)
    at android.support.v7.widget.Toolbar$1.onMenuItemClick(Toolbar.java:203)
    at android.support.v7.widget.ActionMenuView$MenuBuilderCallback.onMenuItemSelected(ActionMenuView.java:780)
    at android.support.v7.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:822)
    at android.support.v7.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:171)
    at android.support.v7.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:973)
    at android.support.v7.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:963)
    at android.support.v7.widget.ActionMenuView.invokeItem(ActionMenuView.java:624)
    at android.support.v7.view.menu.ActionMenuItemView.onClick(ActionMenuItemView.java:150)
    at android.view.View.performClick(View.java:5610)
    at android.view.View$PerformClick.run(View.java:22265)
    at android.os.Handler.handleCallback(Handler.java:751)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:154)
    at android.app.ActivityThread.main(ActivityThread.java:6077)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)

非常感谢您的时间和帮助.如果我的问题看起来不太好请注意,我将教会如何更好地提问