Fragment not following parent activity?

Hi all,

I really hope anyone can help me. I'm busting my head for daaays.

I have a simple MainActivity, with activity_main.xml, which has a DrawerLayout (which shows nicely) and FrameLayout (which is intended for Fragment). Both DrawerLayout and FrameLayout are childrens of simple LinearLayout.

Now, once I start my simple app from phone/emulator, weird thing happen. First, activity appears (as expected) and then Fragment appears but with small delay. So I have to press back button two times in order to get out of the app, even tho I explicitly said to FragmentManager no to put Fragement on the back stack.

My main goal for this demo exercise is to show Fragement (which has couple of Cinema objects through RecyclerView) from within activity. Key idea is to use that FrameLayout (fragment_container) and through it to display fragment's view. (I don't know if this is possible or maybe this is the place where mistake is hidding) And I want Drawer to be present, but froM Activity. Like I said, I did succeed to display, through RecyclerView, those Cinema object (stored in some Singleton helper class). Now, I have to press two times Back to get out of the app, don't want that.

Here is code.

package ftn.sit.vezba4gui2.activities; import androidx.appcompat.app.ActionBarDrawerToggle; import androidx.appcompat.app.AppCompatActivity; import androidx.core.view.GravityCompat; import androidx.drawerlayout.widget.DrawerLayout; //import android.support.v4.DrawerLayout; import androidx.fragment.app.Fragment; import androidx.fragment.app.FragmentManager; import androidx.fragment.app.FragmentTransaction; import android.content.Intent; import android.content.res.Configuration; import android.os.Bundle; import android.util.Log; import android.view.Gravity; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.widget.AdapterView; import android.widget.FrameLayout; import android.widget.LinearLayout; import android.widget.ListView; import android.widget.RelativeLayout; import java.util.ArrayList; import ftn.sit.vezba4gui2.R; import ftn.sit.vezba4gui2.adapters.DrawerListAdapter; import ftn.sit.vezba4gui2.fragements.CinemaListFragment; import ftn.sit.vezba4gui2.tools.FragmentTransition; import model.NavItem; public class MainActivity extends AppCompatActivity {    private DrawerLayout mDrawerLayout;    private ListView mDrawerList;    private FrameLayout mDrawerPane;    private ArrayList<NavItem> mNavItems = new ArrayList<NavItem>();    @Override    protected void onCreate(Bundle savedInstanceState) {        Log.i("TAG", "onCreateFromActivity()");        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        prepareMenu(mNavItems);        mDrawerLayout = findViewById(R.id.drawerLayout);        mDrawerList = findViewById(R.id.drawer_list);        mDrawerPane = findViewById(R.id.drawerPane);        DrawerListAdapter adapter = new DrawerListAdapter(this, mNavItems); //This is BaseAdapter not sowing code for it.        mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);        mDrawerList.setOnItemClickListener(new DrawerItemClickListener());        mDrawerList.setAdapter(adapter);        if (savedInstanceState == null){            selectItemFromDrawer(0);        }    }    @Override    public boolean onOptionsItemSelected(MenuItem item) {        switch (item.getItemId()) {            case R.id.action_settings:                return true;            case R.id.action_refresh:                return true;            case R.id.action_new:                return true;        }        return super.onOptionsItemSelected(item);    }*/    private void prepareMenu(ArrayList<NavItem> mNavItems ){ //This are okey, they display nicely in the drawer        mNavItems.add(new NavItem(getString(R.string.home), getString(R.string.home_long), R.drawable.ic_action_map));        mNavItems.add(new NavItem(getString(R.string.places), getString(R.string.places_long), R.drawable.ic_action_place));        mNavItems.add(new NavItem(getString(R.string.preferences), getString(R.string.preferences_long), R.drawable.ic_action_settings));        mNavItems.add(new NavItem(getString(R.string.about), getString(R.string.about_long), R.drawable.ic_action_about));        mNavItems.add(new NavItem(getString(R.string.sync_data), getString(R.string.sync_data_long), R.drawable.ic_action_refresh));    }    private class DrawerItemClickListener implements ListView.OnItemClickListener {        @Override        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {            selectItemFromDrawer(position);        }    }    private void selectItemFromDrawer(int position) {        if(position == 0){            FragmentTransition.to(new CinemaListFragment(), this, false);        }else if(position == 1){            //..        }else if(position == 2){            //..        }else if(position == 3){            //..        }else if(position == 4){            //..        }else if(position == 5){            //...        }else{            Log.e("DRAWER", "Out of range!");        }        mDrawerList.setItemChecked(position, true);              mDrawerLayout.closeDrawer(mDrawerPane);    } }

FragmentTransition class (I could have posted right there in MainActivity, but our TA told us to do it this way)

public class FragmentTransition {    public static void to(Fragment newFragment, FragmentActivity activity)    {        to(newFragment, activity, true);    }    public static void to(Fragment newFragment, FragmentActivity activity, boolean addToBackstack)    {        FragmentTransaction transaction = activity.getSupportFragmentManager()                .beginTransaction()                .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN)                .replace(R.id.fragment_container, newFragment);        if(addToBackstack) transaction.addToBackStack(null);        transaction.commit();    }    public static void remove(Fragment fragment, FragmentActivity activity) // TODO izbaciti fragment parametar    {        activity.getSupportFragmentManager().popBackStack();    } }


XML for MainActivity

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_height="match_parent"    android:layout_width="match_parent"    android:orientation="vertical"> <androidx.drawerlayout.widget.DrawerLayout    xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/drawerLayout"    android:layout_width="match_parent"    android:layout_height="match_parent">    <!--Main content view-->    <FrameLayout        android:id="@+id/fragment_container"        android:layout_width="match_parent"        android:layout_height="match_parent">    </FrameLayout>    <!--The drawer view-->    <FrameLayout        android:id="@+id/drawerPane"        android:layout_width="280dp"        android:layout_height="match_parent"        android:layout_gravity="start"        >        <!--The navigation drawer menu-->        <ListView            android:id="@+id/drawer_list"            android:layout_width="280dp"            android:layout_height="match_parent"            android:choiceMode="singleChoice"            android:background="#ffffffff" />    </FrameLayout> </androidx.drawerlayout.widget.DrawerLayout> </LinearLayout>

Here is the Fragment from the beginning of the post, I called it CinemaListFragment

package ftn.sit.vezba4gui2.fragements; //I omited the imports (please say if they are neede public class CinemaListFragment extends Fragment {    private RecyclerView mCinemaRecyclerView;    private CinemaAdapter mAdapter;    @Override    public void onCreate(Bundle savedInstanceState) {        Toast.makeText(getActivity(), "onCreateFromFragment()", Toast.LENGTH_SHORT).show();        Log.i("TAG", "onCreateFromFragment()");        super.onCreate(savedInstanceState);        //setHasOptionsMenu(true);    }    @Override    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {        View root = inflater.inflate(R.layout.fragment_cinema_list, container, false);        mCinemaRecyclerView = (RecyclerView) root.findViewById(R.id.cinema_recycler_view);        mCinemaRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));        updateFragmentUI();        return root;    }    @Override    public void onActivityCreated(@Nullable Bundle savedInstanceState) {        super.onActivityCreated(savedInstanceState);       // I cannot start here initializing my view for this fragement?    }    private void updateFragmentUI() {        CinemaRepository repo = CinemaRepository.get(getActivity()); //singleton        ArrayList<Cinema> cinemas = repo.getCinemas();        if (mAdapter == null){            mAdapter = new CinemaAdapter(cinemas);            mCinemaRecyclerView.setAdapter(mAdapter);        }  else {           // mAdapter.setCinemas(cinemas);            mAdapter.notifyDataSetChanged();        }    }    private class CinemaHolder extends RecyclerView.ViewHolder implements View.OnClickListener{        private Cinema mCinema;        private TextView name;        private TextView description;        private ImageView image;        public CinemaHolder(View itemView) {            super(itemView);            name = (TextView)itemView.findViewById(R.id.name);            description = (TextView)itemView.findViewById(R.id.description);            image = (ImageView)itemView.findViewById(R.id.item_icon);            itemView.setOnClickListener(this);        }        public void bindCinema(Cinema cinema) {            mCinema = cinema;            name.setText(cinema.getName());            description.setText(cinema.getDescription());            if (cinema.getAvatar() != -1){                image.setImageResource(cinema.getAvatar());            }        }        @Override        public void onClick(View v) {          //Here I will start some other Activity which will display details of each Cinema but through ViewPager           // Intent intent = CrimePagerActivity.newIntent(getActivity(), mCrime.getId());            //startActivity(intent);        }    }    private class CinemaAdapter extends RecyclerView.Adapter<CinemaHolder> {        private ArrayList<Cinema> mCinemas;        public CinemaAdapter(ArrayList<Cinema> cinemas)        {            mCinemas = cinemas;        }        @Override        public CinemaHolder onCreateViewHolder(ViewGroup parent, int viewType) {            /*onCreateViewHolder is called by the RecyclerView when it needs a new View to display an item. In            this method, you create the View and wrap it in a ViewHolder. The RecyclerView does not expect that            you will hook it up to any data yet.            For the View, you inflate a layout from the Android standard library called simple_list_item_1 (or we can            create our own view).*/            LayoutInflater layoutInflater = LayoutInflater.from(getActivity());            View view = layoutInflater.inflate(R.layout.list_item_cinema, parent, false);                return new CinemaHolder(view);        }        @Override        public void onBindViewHolder(CinemaHolder holder, int position) {            /*onBindViewHolder: This method will bind a ViewHolder’s View to your model object. It receives            the ViewHolder and a position in your data set. To bind your View, you use that position to find the            right model data. Then you update the View to reflect that model data.            In your implementation, that position is the index of the Cinema in your list. Once you pull it out, you            bind that Cinema to your View by sending its title to your ViewHolder’s view.*/            Cinema cinema = mCinemas.get(position);            holder.bindCinema(cinema);        }        @Override        public int getItemCount() {            return mCinemas.size();        }        public void setCinemas(ArrayList<Cinema> cinemas) {            mCinemas = cinemas;        }    } }

And finally code for simple RecyclerView for this Fragement (fragement_cinema_list):

<?xml version="1.0" encoding="utf-8"?> <androidx.recyclerview.widget.RecyclerView    xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/cinema_recycler_view"    android:layout_width="match_parent"    android:layout_height="match_parent"/>

I apologize for this long code post. If necessary, I could send zip of the project. It is not big, simple student exercise.

Lets go Ranchers

Is the issue fixed?

Nope...

You miss to paste Cinema class and DrawerListAdapter. Consider post it in git, so we can clone it down and test.

Hi Randy,

Here is link to GitHub project.