Generic Social Links Implementation in Open Event Android App

The Open Event Android App has an About Fragment which displays all the info about the event like name, time, location etc. It also shows social media buttons for the event. The problem was that the implementation of showing the social media buttons was not generic. The implementation was working fine for current FOSSASIA sample. If we generate the app for other events it creates a problem. It shows static buttons without proper mapping from social media button to social media link which creates a problem like on clicking GitHub button it opens Facebook link (issue #1792).

One solution to this problem is to implement recyclerview with social media buttons. In this post I explain how I have made social links implementation generic using RecyclerView.

Add RecyclerView in layout

The first step to do is to add recyclerview in the layout xml file and to create a list item for recyclerview which holds the image for the social link button. Then in the About Fragment find recyclerview element added in the xml file using findFragmentById() method.

1. Add recyclerview in xml file

In the layout xml file of About Fragment add recyclerview element. Define id, width, height, and gravity of recyclerview. Then specify list item for recyclerview using listitem attribute.

<android.support.v7.widget.RecyclerView
            android:id="@+id/list_social_links"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:overScrollMode="never"
            android:clipToPadding="false"
            tools:listitem="@layout/item_social_link" />

2. Create item_social_link.xml

Now create a item_social_link.xml file and add a FrameLayout element. Inside the FrameLayout add an ImageView with appropriate id, width, height and padding.

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/layout_social_link_parent"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">

    <ImageView
        android:id="@+id/img_social_link"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="?attr/selectableItemBackgroundBorderless"
        android:contentDescription="@string/social_link"
        android:padding="@dimen/padding_large"
        android:tint="@color/white" />
</FrameLayout>

Add and initialize RecyclerView

After adding recyclerview in xml file we need to add RecyclerView field in the About Fragment java file. Now add and initialize SocialLinksListAdapter which extends RecyclerView.Adapter and will be used for populating the recyclerview with the social links.

@BindView(R.id.list_social_links)
protected RecyclerView socialLinksRecyclerView;

private SocialLinksListAdapter socialLinksListAdapter;
private List<SocialLink> mSocialLinks = new ArrayList<>();

Here mSocialLinks is the list of social links which is fetched from the Event object.

Create ViewHolder for social link button

Now create SocialLinkViewHolder which extends RecyclerView.ViewHolder and holds one social link item defined in item_social_link.xml file. This file is where the magic happens. Add ImageView, FrameLayout, SocialLink and context fields in it.

public class SocialLinkViewHolder extends RecyclerView.ViewHolder {

    @BindView(R.id.img_social_link)
    protected ImageView imageView;

    @BindView(R.id.layout_social_link_parent)
    protected FrameLayout layout;

    private SocialLink socialLink;
    private Context context;

    public SocialLinkViewHolder(View itemView, Context context) {
        super(itemView);
        ButterKnife.bind(this, itemView);
        this.context = context;
    }

    public void bindSocialLink(@NonNull SocialLink socialLink) {...}

    private void setImageDrawable(@NonNull String name,@NonNull String link) {...}

    private Drawable getDrawable(@DrawableRes int id) {...}

    private void showView(boolean show) {...}
}

The bindSocialLink(SocialLink socialLink) method is called in the onBindViewHolder() method of the SocialLinksListAdapter. In this method initialize socialLink field and set drawable for ImageView according to SocialLink name using setImageDrawable() method.

public void bindSocialLink(@NonNull SocialLink socialLink) {
        this.socialLink = socialLink;
        setImageDrawable(socialLink.getName(), socialLink.getLink());
}

The setImageDrawable() method finds and sets appropriate image for social link button using the name of the social link. If the image for the social link is not found then it sets the visibility of the image view to GONE using showView(boolean show).

private void setImageDrawable(@NonNull String name,@NonNull String link) {

        if (Utils.isEmpty(name) || Utils.isEmpty(link) || Utils.getSocialLinkDrawableId(name) == 1) {
            showView(false);
            return;
        }
        imageView.setImageDrawable(getDrawable(Utils.getSocialLinkDrawableId(name)));
}

The showView(boolean show) method handles visibility of ImageView and ImageView’s parent FrameLayout using setVisibility() method.

private void showView(boolean show) {
        if (show) {
            imageView.setVisibility(View.VISIBLE);
            layout.setVisibility(View.VISIBLE);
        } else {
            imageView.setVisibility(View.GONE);
            layout.setVisibility(View.GONE);
        }
}

Set onClickListener to ImageView

Now it’s time to set the onClickListener in the constructor of the SocialLinkViewHolder to define what to do when user clicks on the ImageView.

imageView.setOnClickListener(view -> {
            if (socialLink != null && !Utils.isEmpty(socialLink.getLink())) {
                Utils.setUpCustomTab(context, socialLink.getLink());
            }
        });

Here we are setting custom tab for the social link using the setUpCustomTab() util method which will open the link.

Now run the app on the device or emulator. Here’s how it looks like,

Conclusion

The SocialLink impementation using the RecyclerView gives the great user experience in the application.

Additional resources

Addition of Bookmarks to the Homescreen in the Open Event Android App

In the Open Event Android app we had already built the new homescreen but the users only had access to bookmarks in a separate page which could be accessed from the navbar.If the bookmarks section were to be incorporated in the homescreen itself, it would definitely improve its access to the user. In this blog post, I’ll be talking about how this was done in the app.

These 2 images show the homescreen and the bookmarks section respectively.

No Bookmark View
Bookmark View

 

 

 

 

 

 

 

 

 

This was the proposed homescreen page for the app. This would provide easy access to important stuff to the user such as event venue,date,description etc. Also the same homescreen would also have the bookmarks showing at the top if there are any.

The list of bookmarks in the first iteration of design was modeled to be a horizontal list of cards.

Bookmarks Merging Process

These are some variables for reference.

private SessionsListAdapter sessionsListAdapter;
 private RealmResults<Session> bookmarksResult;
 private List<Session> mSessions = new ArrayList<>();

The code snippet below highlights the initial setup of the bookmarks recycler view for the horizontal List of cards. All of this is being done in the onCreateView callback of the AboutFragment.java file which is the fragment file for the homescreen.

bookmarksRecyclerView.setVisibility(View.VISIBLE);
 sessionsListAdapter = new SessionsListAdapter(getContext(), mSessions, bookmarkedSessionList);
 sessionsListAdapter.setBookmarkView(true);
 bookmarksRecyclerView.setAdapter(sessionsListAdapter);
 bookmarksRecyclerView.setLayoutManager(new LinearLayoutManager(getContext(),LinearLayoutManager.HORIZONTAL,false));

The SessionListAdapter is an adapter that was built to handle multiple types of displays of the same viewholder i.e SessionViewHolder . This SessionListAdapter is given a static variable as an argument which is just notifies the adapter to switch to the bookmarks mode for the adapter.

private void loadData() {
    bookmarksResult = realmRepo.getBookMarkedSessions();
    bookmarksResult.removeAllChangeListeners();
    bookmarksResult.addChangeListener((bookmarked, orderedCollectionChangeSet) -> {
        mSessions.clear();
        mSessions.addAll(bookmarked);
 
        sessionsListAdapter.notifyDataSetChanged();
 
        handleVisibility();
    });
 }

This function loadData() is responsible for extracting the sessions that are bookmarked from the local Realm database. We the update the BookmarkAdapter on the homescreen with the list of the bookmarks obtained. Here we see that a ChangeListener is being attached to our RealmResults. This is being done so that we do our adapter notify only after the data of the bookmarked sessions has been processed from a background thread.

if(bookmarksResult != null)
    bookmarksResult.removeAllChangeListeners();

And it is good practice to remove any ChangeListeners that we attach during the fragment life cycle in the onStop() method to avoid memory leaks.

So now we have successfully added bookmarks to the homescreen.

Resources

Better Bookmark Display Viewholder in Home Screen of the Open Event Android App

Earlier in the Open Event Android app we had built the homescreen with the bookmarks showing up at the top as a horizontal list of cards but it wasn’t very user-friendly in terms of UI. Imagine that a user bookmarks over 20-30 sessions, in order to access them he/she might have to scroll horizontally a lot in order to access his/her bookmarked session. So this kind of UI was deemed counter-intuitive. A new UI was proposed involving the viewholder used in the schedule page i.e DayScheduleViewHolder, where the list would be vertical instead of horizontal. An added bonus was that this viewholder conveyed the same amount of information on lesser white space than the earlier viewholder i.e SessionViewHolder.

Old Design
New Design

 

 

 

 

 

 

 

 

 

Above are two images, one in the initial design, the second in the new design. In the earlier design the number of bookmarks visible to the user at a time was at most 1 or 2 but now with the UI upgrade a user can easily see up-to 5-6 bookmarks at a time. Additionally there is more relevant content visible to the user at the same time.

Additionally this form of design also adheres to Google’s Material Design guidelines.

Code Comparison of the two Iterations

Initial Design
sessionsListAdapter = new SessionsListAdapter(getContext(), mSessions, bookmarkedSessionList);
 sessionsListAdapter.setBookmarkView(true);
 bookmarksRecyclerView.setAdapter(sessionsListAdapter);
 bookmarksRecyclerView.setLayoutManager(new LinearLayoutManager(getContext(),LinearLayoutManager.HORIZONTAL,false));

Here we are using the SessionListAdapter for the bookmarks. This was previously being used to display the list of sessions inside the track and location pages. It is again being used here to display the horizontal list of bookmarks.To do this we are using the function setBookmarkView(). Here mSessions consists the list of bookmarks that would appear in the homescreen.

Current Design
bookmarksRecyclerView.setVisibility(View.VISIBLE);
 bookMarksListAdapter = new DayScheduleAdapter(mSessions,getContext());
 bookmarksRecyclerView.setAdapter(bookMarksListAdapter);
 bookmarksRecyclerView.setLayoutManager(new LinearLayoutManager(getContext()));

Now we are using the DayScheduleAdapter which is the same adapter used in the schedule page of the app. Now we use a vertical layout instead of a horizontal layout  but with a new viewholder design. I will be talking about the last line in the code snippet shortly.

ViewHolder Design (Current Design)

<RelativeLayout android:id="@+id/content_frame">
    <LinearLayout android:id="@+id/ll_sessionDetails">
        <TextView android:id="@+id/slot_title"/>
        <RelativeLayout>
            <TextView android:id="@+id/slot_start_time”/>
            <TextView android:id="@+id/slot_underscore"/>
            <TextView android:id="@+id/slot_end_time"/>

           <TextView android:id="@+id/slot_comma"/>
            <TextView android:id="@+id/slot_location”/>
            <Button android:id="@+id/slot_track"/>
            <ImageButton android:id="@+id/slot_bookmark"/>
        </RelativeLayout>

    </LinearLayout>
    <View android:id=”@+id/divider”/>
 </RelativeLayout>

This layout file is descriptive enough to highlight each element’s location.

In this viewholder we can also access to the track page from the track tag and can also remove bookmarks instantly.

The official widget to make a scroll layout in android is ScrollView. Basically, adding a RecyclerView inside ScrollView can be difficult . The problem was that the scrolling became laggy and weird.  Fortunately, with the appearance of Material Design , NestedScrollView was released and this becomes much easier.

bookmarksRecyclerView.setNestedScrollingEnabled(false);

With this small snippet of code we are able to insert a RecyclerView inside the NestedScrollView without any scroll lag.
So now we have successfully updated the UI/UX for the homescreen  to meet the requirements as given by the Material Design guidelines.

Resources

GlobalSearchAdapter Setup in Open Event Android App

In this blog post I describe how the GlobalSearchAdapter in Open Event Android was made which enabled users to search quickly within the app. This post also outlines how to create Recycler Views with heterogenous layouts and explains how to write ViewHolders.

Adapter Logic

A custom adapter was built for the population of views in the Recycler View in the SearchActivity.

private List<Object> filteredResultList = new ArrayList<>();
//ViewType Constants
private final int TRACK = 0;
private final int SPEAKER = 2;
private final int LOCATION = 3;
private final int DIVIDER = 4;

The DIVIDER constant was assigned to the Result Type Header View.

In a gist all the item types such as Speaker, Track, Location, Divider etc have been designated some constants.

Getting the ItemViewType

@Override
public int getItemViewType(int position) {

   if(filteredResultList.get(position) instanceof Track){
       return TRACK;
   }
   else if(filteredResultList.get(position) instanceof String){
       return DIVIDER;
   }
   ...Similarly for other ItemTypes such as Session or Location
   else{
       return 1;
   }
}

As the filteredResultList is of type Object we can insert objects of any type into the list as Object is a superclass of all classes. We would want a view which represents a TRACK if we have an object of type Track in the filteredResultList. And similarly for the other result types we could insert objects of type LOCATION, SPEAKER types in this list. getItemViewType() basically determines the type of the item that is visible to us. If the list consists of an item of type SPEAKER, in the RecyclerView.

Speaker Item Type
Track Item Type
Divider Item Type
Location Item Type

Code for onCreateViewHolder in GlobalSearchAdapter for the Recycler View

@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

   RecyclerView.ViewHolder resultHolder = null;
   LayoutInflater inflater = LayoutInflater.from(parent.getContext());

   switch(viewType) {
       case TRACK:
           View track = inflater.inflate(R.layout.item_track, parent,   false);
           resultHolder = new TrackViewHolder(track,context);
           break;
       case SPEAKER:
           View speaker = inflater.inflate(R.layout.search_item_speaker, parent, false);
           resultHolder = new SpeakerViewHolder(speaker,context);
           break;
       //Similarly for other types
       default:
           break;
   }
   return resultHolder;
}

Depending upon the the viewType returned the desired layout is inflated and the desired ViewHolder is returned.

Code for onBindViewHolder in GlobalSearchAdapter for the Recycler View

@Override
 public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
 
    switch (holder.getItemViewType()){
        case TRACK:
            TrackViewHolder trackSearchHolder = (TrackViewHolder)holder;
            final Track currentTrack = (Track)getItem(position);
            trackSearchHolder.setTrack(currentTrack);
            trackSearchHolder.bindHolder();
            break;
         //Similarly for all the other View Types
        default:
            break;
    }
 }

These functions are being used to bind the data to the layouts that have been inflated already in the earlier snippet of code of onCreateViewHolder.

The bindHolder functions of each ViewHolder type are being used to do the view binding i.e converting the information in the Object Track into what we see in the TrackViewHolder as seen in TrackViewFormat.

All ViewHolders have been defined as separate classes in order to enable re usability of these classes.

ViewHolder Implementation

There are 4 main ViewHolders that were made to enable such a search. I’ll be talking about the TrackViewHolder in detail.

public class TrackViewHolder extends RecyclerView.ViewHolder {
    
    @BindView(R.id.imageView)
    ImageView trackImageIcon;
    @BindView(R.id.track_title)
    TextView trackTitle;
    @BindView(R.id.track_description)
    TextView trackDescription;
 
    private Track currentTrack;
    private Context context;
    private TextDrawable.IBuilder drawableBuilder = TextDrawable.builder().round();
 
    public void setTrack(Track track) {
        this.currentTrack = track;
    }
 
    public TrackViewHolder(View itemView,Context context) {
        super(itemView);
        ButterKnife.bind(this, itemView);
        this.context = context;
    }
    public void bindHolder(){
 
        //Set all Views to their correct configurations
        itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(context,   TrackSessionsActivity.class);
                intent.putExtra(ConstantStrings.TRACK,   currentTrack.getName());
 
                // Send Track ID to Activity to leverage color cache
                intent.putExtra(ConstantStrings.TRACK_ID,   currentTrack.getId());
                context.startActivity(intent);
            }
        });
} }

Those @BindView annotations that we can see are the result of a library called as Butterknife which is used to reduce standard boilerplate findViewById lines.

@BindView(R.id.imageView) ImageView trackImageIcon;
IS THE SAME AS THIS  
ImageView trackImageIcon = (ImageView)findViewById(R.id.imageView);

The advantage of such a ViewHolder is that it knows what kind of data it stores as compared to traditional ViewHolders which do not know the kind of data it stores.

By making ViewHolders separate from the RecyclerViewAdapter we are essentially decoupling classes and are enabling reusability of code. Also we make the ViewHolder a bit more intelligent by storing the object it binds in the ViewHolder itself. In the above example we are storing an object of Track which is bind to the ViewHolder. We also see that we do the view binding inside the viewholder itself. All this helps us to reduce code inside the adapter class.

A recent addition to the app was custom colors for all TRACKS in the app that improved the visual feel of the app. So basically, for example if a SESSION has been associated with the track of Blockchain it would be given a color such as purple. onClickListeners are also being set with some extras which are self-descriptive in nature. Similarly the other ViewHolders have been implemented.

Resources

Global Search in Open Event Android

In the Open Event Android app we only had a single data source for searching in each page that was the content on the page itself. But it turned out that users want to search data across an event and therefore across different screens in the app. Global search solves this problem. We have recently implemented  global search in Open Event Android that enables the user to search data from the different pages i.e Tracks, Speakers, Locations etc all in a single page. This helps the user in obtaining his desired result in less time. In this blog I am describing how we implemented the feature in the app using JAVA and XML.

Implementing the Search

The first step of the work is to to add the search icon on the homescreen. We have done this with an id R.id.action_search_home.

@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
   super.onCreateOptionsMenu(menu, inflater);
   inflater.inflate(R.menu.menu_home, menu);
   // Get the SearchView and set the searchable configuration
   SearchManager searchManager = (SearchManager)getContext().    getSystemService(Context.SEARCH_SERVICE);
   searchView = (SearchView) menu.findItem(R.id.action_search_home).getActionView();
  // Assumes current activity is the searchable activity
 searchView.setSearchableInfo(searchManager.getSearchableInfo(
getActivity().getComponentName()));
searchView.setIconifiedByDefault(true); 
}

What is being done here is that the search icon on the top right of the home screen  is being designated a searchable component which is responsible for the setup of the search widget on the Toolbar of the app.

@Override
 public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.menu_home, menu);
    SearchManager searchManager =
            (SearchManager) getSystemService(Context.SEARCH_SERVICE);
    searchView = (SearchView) menu.findItem(R.id.action_search_home).getActionView();
    searchView.setSearchableInfo(
            searchManager.getSearchableInfo(getComponentName()));
 
    searchView.setOnQueryTextListener(this);
    if (searchText != null) {
        searchView.setQuery(searchText, true);
    }
    return true; }

We can see that a queryTextListener has been setup in this function which is responsible to trigger a function whenever a query in the SearchView changes.

Example of a Searchable Component

<?xml version="1.0" encoding="utf-8"?>
 <searchable xmlns:android="http://schemas.android.com/apk/res/android"
    android:hint="@string/global_search_hint"
    android:label="@string/app_name" />

For More Info : https://developer.android.com/guide/topics/search/searchable-config.html

If this searchable component is inserted into the manifest in the required destination activity’s body the destination activity is set and intent filter must be set in this activity to tell whether or not the activity is searchable.

Manifest Code for SearchActivity

<activity
        android:name=".activities.SearchActivity"
        android:launchMode="singleTop"
        android:label="Search App"
        android:parentActivityName=".activities.MainActivity">
    <intent-filter>
        <action android:name="android.intent.action.SEARCH" />
    </intent-filter>
    <meta-data
        android:name="android.app.searchable"
        android:resource="@xml/searchable" />
 </activity>

And the attribute  android:launchMode=”singleTop is very important as if we want to search multiple times in the SearchActivity all the instances of our SearchActivity would get stored on the call stack which is not needed and would also eat up a lot of memory.

Handling the Intent to the SearchActivity

We basically need to do a standard if check in order to check if the intent is of type ACTION_SEARCH.

if (Intent.ACTION_SEARCH.equals(getIntent().getAction())) {
    handleIntent(getIntent());
 }
@Override
 protected void onNewIntent(Intent intent) {
    super.onNewIntent(intent);
    handleIntent(intent);
 }
 public void handleIntent(Intent intent) {
    final String query = intent.getStringExtra(SearchManager.QUERY);
    searchQuery(query);
 }

The function searchQuery is called within handleIntent in order to search for the text that we received from the Homescreen.

SearchView Trigger Functions

Next we need to add two main functions in order to get the search working:

  • onQueryTextChange
  • onQueryTextSubmit

The function names are self-explanatory. Now we will move on to the code implementation of the given functions.

@Override
 public boolean onQueryTextChange(String query) {
    if(query!=null) {
        searchQuery(query);
        searchText = query;
    }
    else{
        results.clear();
        handleVisibility();
    }
   return true;
 }
 
 @Override
 public boolean onQueryTextSubmit(String query) {
    searchView.clearFocus();
    return true;
 }

The role of the searchView.clearFocus() inside the above code snippet is to remove the keyboard popup from the screen to enable the user to have a clear view of the search result.

Here the main search logic is being handled by the function called searchQuery which I’ll talking about now.

Search Logic

private void searchQuery(String constraint) {
 
    results.clear();
 
    if (!TextUtils.isEmpty(constraint)) {
        String query = constraint.toLowerCase(Locale.getDefault());
        addResultsFromTracks(query);
        addResultsFromSpeakers(query);
        addResultsFromLocations(query);
    }
 }
//THESE ARE SOME VARIABLES FOR REFERENCE
//This is the custom recycler view adapter that has been defined for the search
private GlobalSearchAdapter globalSearchAdapter;
 //This stores the results in an Object Array
 private List<Object> result

We are assuming that we have POJO’s(Plain Old Java Objects) for Tracks , Speakers , and Locations and for the Result Type Header.

The code posted below performs the function of getting the required results from the list of tracks. All the results are being fetched asynchronously from Realm and here we have also attached a header for the result type to denote whether the result is of type Track , Speaker or Location. We also see that we have added a changeListener to notify us if any changes have occurred in the set of results.

Similarly this is being done for all the result types that we need i.e Tracks, Locations and Speakers.

public void addResultsFromTracks(String queryString) {

   RealmResults<Track> filteredTracks = realm.where(Track.class)
                                        .like("name", queryString,                     Case.INSENSITIVE).findAllSortedAsync("name");
      filteredTracks.addChangeListener(tracks -> {

       if(tracks.size()>0){
            results.add("Tracks");
        }
       results.addAll(tracks);
       globalSearchAdapter.notifyDataSetChanged();
       Timber.d("Filtering done total results %d", tracks.size());
       handleVisibility();
});}

We now have a “Global Search” feature in the Open Event Android app. Users had asked for this feature and a learning for us is, that it would have been even better to do more tests with users when we developed the first versions. So, we could have included this feedback and implemented Global Search earlier on.

Resources

Using FastAdapter in Open Event Organizer Android Project

RecyclerView is an important graphical UI component in any android application. Android provides RecyclerView.Adapter class which manages all the functionality of RecyclerView. I don’t know why but android people have kept this class in a very abstract form with only basic functionalities implemented by default. On the plus side it opens many doors for custom adapters with new functionalities for example, sticky headers, scroll indicator, drag and drop actions on items, multiview types items etc. A developer should be able to make an adapter of his need by extending RecyclerView.Adapter. There are many custom adapters developers have shared which comes with built in functionalities. FastAdapter is one of them which comes with all the good functionalities built in and also it is very easy to use. I just got to use this in the Open Event Organizer Android App of which the core feature is Attendees Check In. We have used FastAdapter library to show attendees list which needs many features which are absent in plane RecyclerView.Adapter. FastAdapter is built in such way that there are many different ways of using it on developer’s need. I have found a simplest way which I will be sharing here. The first part is extending the item model to inherit AbstractItem.

public class Attendee extends AbstractItem<Attendee, AttendeeViewHolder> {
[email protected]
  private long id;
  ...
  ...

[email protected]
  public long getIdentifier() {
      return id;
  }

[email protected]
  public int getType() {
      return 0;
  }

[email protected]
  public int getLayoutRes() {
      return R.layout.attendee_layout;
  }

[email protected]
  public AttendeeViewHolder getViewHolder(View view) {
      return new AttendeeViewHolder(DataBindingUtil.bind(view));
  }

[email protected]
  public void bindView(AttendeeViewHolder holder, List<Object> list) {
      super.bindView(holder, list);
      holder.bindAttendee(this);
  }

[email protected]
  public void unbindView(AttendeeViewHolder holder) {
      super.unbindView(holder);
      holder.unbindAttendee();
  }
}

The methods are pretty obvious by name. Implement these methods accordingly. You may notice that we have used Databinding here to bind data to views but it is not necessary. Also you will have to create your ViewHolder for adapter. You can either use RecyclerView.ViewHolder or you can just create a custom one by inheriting it as per your need. Once this part is over you are half done as most of the things are been taken care in model itself. Now we will be writing code for adapter and setting it to your RecyclerView.

FastItemAdapter<Attendee> fastItemAdapter = new FastItemAdapter<>();
fastItemAdapter.setHasStableIds(true);
...
// functionalities related code
...
recyclerView.setAdapter(fastItemAdapter);

Initialize FastItemAdapter which will be our main adapter handling all the direct functions related to the RecyclerView. Set up some boolean constants according to the project need. In our project we have Attendee model which has id as a primary field. FastItemAdapter can take advantage of distinct field of the model called as identifier . Hence it is set true as Attendee model has id field. But you should be careful about setting it to True as then you must have implemented getIdentifier in the model to return correct field which will be used as an identifier by our adapter. And the adapter is good to set to the RecyclerView.

Now we got to decide which functionalities we will be implementing to our RecyclerView. In our case we needed: 1. Search filter for attendees, 2. Sticky header for attendees groups arranged alphabetically and 3. On click listener for attendee item.

FastItemAdapter has ItemFilter adapter wrapped inside which manages all the filtering stuff. Filtering logic can be set using it.

fastItemAdapter.getItemFilter().withFilterPredicate(this::shallFilter);

Where shallFilter is method which takes attendee object and returns boolean whether to filter the item or not. And after this you can use FastItemAdapter’s filter method to filter the items. For sticky headers you need to implement StickyRecyclerHeadersAdapter extending AbstractAdapter. In this class you will have to implement your filter logic in getHeaderId method. This must return an unique id for items of the same group.

@Override
public long getHeaderId(int position) {
   IItem item = getItem(position);
   if(item instanceof Attendee && ((Attendee)item).getFirstName() != null)
       return ((Attendee) item).getFirstName().toUpperCase().charAt(0);
   return -1;
}

Like in this case we have grouped attendees alphabetically hence just returning initial character’s ASCII value will do good. You can modify this method according to your need. For other unimplemented methods just keep their default return values. With this you will also have to implement onCreateHeaderViewHolder and onBindHeaderViewHolder methods to bind view and data to the header layout. Once this is done you are ready to set sticky headers to your RecyclerView with following code:

stickyHeaderAdapter = new StickyHeaderAdapter();
final HeaderAdapter headerAdapter = new HeaderAdapter();
recyclerView.setAdapter(stickyHeaderAdapter.wrap((headerAdapter.wrap(fastItemAdapter))));

final StickyRecyclerHeadersDecoration decoration = new StickyRecyclerHeadersDecoration(stickyHeaderAdapter);
recyclerView.addItemDecoration(decoration);
adapterDataObserver = new RecyclerView.AdapterDataObserver() {
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   public void onChanged() {
       decoration.invalidateHeaders();
   }
};
stickyHeaderAdapter.registerAdapterDataObserver(adapterDataObserver);

For click listener, the code is similar to the RecyclerView.Adapter’s one.

fastItemAdapter.withOnClickListener(new FastAdapter.OnClickListener<Item>() {
  @Override
  public boolean onClick(View v, IAdapter<Item> adapter, Item item, int position) {
     // your on click logic
   return true;
  }
});

With this now you have successfully implemented FastItemAdapter to your RecyclerView. Although there are some important points to be taken care of. If you are using filter in your application then you will have to modify your updateItem logic. As when filter is applied to the adapter its items list is filtered. And if you are updating the item using its position from original list it then it will result in exception or updating the wrong item. So you will have to change the position to the one in filtered list. For example the updateAttendee method from Organizer App code looks like this:

public void updateAttendee(int position, Attendee attendee) {
   position = fastItemAdapter.getAdapterPosition(attendee);
   fastItemAdapter.getItemFilter().set(position, attendee);
}