Using Entry List Screenlet

You’ll use Entry List Screenlet by following the same steps to use any Screenlet: insert the Screenlet’s XML in an activity or fragment layout, and then implement the Screenlet’s listener in the activity or fragment class. You’ll follow these steps here to insert Entry List Screenlet in EntriesFragment.

First, you’ll insert Entry List Screenlet’s XML in EntriesFragment’s layout, fragment_entries.xml.

Inserting the Screenlet in the Layout

Inserting Entry List Screenlet’s XML is very simple. Since all you want fragment_entries.xml to do is display the Screenlet, it must only contain the Screenlet’s XML. Replace the contents of fragment_entries.xml with the following markup:

<com.liferay.docs.entrylistscreenlet.EntryListScreenlet
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/entrylist_screenlet"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layoutId="@layout/list_entries"/>

As with Guestbook List Screenlet, you’ll use the android:id value to get a Screenlet reference. Next, you must implement the Screenlet’s listener.

Implementing the Screenlet’s Listener

Recall that to use a Screenlet, you must implement its listener. The listener methods let the app developer respond to the Screenlet’s behavior in the activity or fragment class that contains the Screenlet. Also recall that because Guestbook List Screenlet didn’t need extra listener methods, you used it in GuestbooksActivity by implementing the BaseListListener interface with GuestbookModel as a type argument. Entry List Screenlet also doesn’t need extra listener methods. Like Guestbook List Screenlet, you can use it by implementing BaseListListener with its model class as a type argument.

Follow these steps to implement Entry List Screenlet’s listener in EntriesFragment:

1. Change EntriesFragment’s class declaration to implement BaseListListener<EntryModel>. The class declaration should now look like this:

   public class EntriesFragment extends Fragment implements BaseListListener<EntryModel> {...
   

   This requires that you add the following imports:

   import com.liferay.docs.model.EntryModel;
   import com.liferay.mobile.screens.base.list.BaseListListener;
   

2. Now you must implement the listener’s methods. Recall that this includes the BaseCacheListener interface’s, error method, since BaseListListener extends BaseCacheListener. For a full explanation of the methods in both listeners, see using Guestbook List Screenlet. Note that in EntriesFragment, you don’t need to take any action in these methods. There are no UI elements or other parts of the fragment that must be updated or processed in response to the Screenlet’s behavior. All this Screenlet must do is display its content, which it does regardless of anything you do in the listener methods. The only thing you may want to add is a toast message in onListPageFailed to notify the user if the server call fails, but this isn’t required. Implement these methods now:

   @Override
   public void onListPageFailed(int startRow, Exception e) {
       Toast.makeText(getActivity(), "Page request failed", Toast.LENGTH_LONG).show();
   }
   
   @Override
   public void onListPageReceived(int startRow, int endRow, List<EntryModel> entries, int rowCount) {
   
   }
   
   @Override
   public void onListItemSelected(EntryModel entry, View view) {
   
   }
   
   @Override
   public void error(Exception e, String userAction) {
   
   }
   

   This requires you to add the following imports:

   import android.widget.Toast;
   import java.util.List;
   

3. Now you’re ready to register EntriesFragment as the Screenlet’s listener. You’ll do this the same way you registered GuestbooksActivity as Guestbook List Screenlet’s listener: get a reference to the Screenlet and call its setListener method. After doing this, you’ll use the Entry List Screenlet reference’s setGuestbookId method to set its guestbook ID. This sets the guestbook where the Screenlet gets its entries. You’ll do these things in the onCreateView method. Replace the onCreateView method with this updated version:

   @Override
   public View onCreateView(LayoutInflater inflater, ViewGroup container,
                            Bundle savedInstanceState) {
       // Inflate the layout for this fragment
       View view = inflater.inflate(R.layout.fragment_entries, container, false);
       long guestbookId = getArguments().getLong("guestbookId");
   
       EntryListScreenlet screenlet = (EntryListScreenlet) view.findViewById(R.id.entrylist_screenlet);
       screenlet.setListener(this);
       screenlet.setGuestbookId(guestbookId);
   
       return view;
   }
   

   This requires you to import com.liferay.docs.entrylistscreenlet.EntryListScreenlet.

   As you can see, onCreateView now registers EntriesFragment as the Screenlet’s listener and sets the Screenlet’s guestbook ID. The rest of onCreateView is unchanged.

Now run the app in the emulator and log in with your credentials when prompted. The app then presents you with the first guestbook’s entries. Open the navigation drawer by pressing the hamburger button, then select a different guestbook. The drawer then closes to show the selected guestbook’s entries. Nice work! Your app now uses Guestbook List Screenlet and Entry List Screenlet to show the same guestbooks and entries as the Guestbook portlet. The following screenshots show these Screenlets in action.

Figure 1: Entry List Screenlet displays guestbook entries in your app.

Figure 2: Guestbook List Screenlet displays guestbooks in the navigation drawer.

Although your Screenlets work, you may have noticed something odd about the navigation drawer’s header–it’s hideous. The action bar is somewhere on the purple-blue spectrum, while the drawer header is green. You’ve probably seen more attractive finger paintings. Fortunately, it’s simple to change the drawer header’s color. Also, the drawer header contains the generic text Android Studio. You should change this to something more suitable for your app, like Liferay Guestbook.

Follow these steps to apply these changes to the drawer header:

1. In res/drawable/side_nav_bar.xml, replace android:centerColor, android:endColor, and android:startColor with the following settings:

   android:centerColor="@color/colorPrimary"
   android:endColor="@color/colorPrimaryDark"
   android:startColor="@color/colorPrimary"
   

   This sets the drawer header’s colors to match the colors used in the rest of the app.

2. Define the following string resource in res/values/strings.xml:

   <string name="liferay_guestbook">Liferay Guestbook</string>
   

3. In nav_header_guestbooks.xml, find the TextView element that contains android:text="Android Studio", and replace Android Studio with @string/liferay_guestbook. You can delete any other TextView elements in this file. Run the app again, and open the drawer after signing in. The drawer header now shows your greeting. It’s a lot prettier too.

Figure 3: The drawer header looks a lot better after some light customization.

Congratulations! Now you know how to use Liferay Screens and create your own Screenlets. This opens up a world of possibilities for developing apps that leverage Liferay Portal. Although you learned a great deal in this Learning Path, there’s still more. You can customize your Screenlet’s appearance, package it for redistribution, and even configure it to receive push notifications. These topics, and more, are covered in the tutorials on Android apps with Liferay Screens.