Design Pattern

Singleton

Just like firebase, we build a custom WebSocket singleton to control the creation of our WebSocket client, In this case, only 1 client can be created across our app, reducing the potential workload and the number of network connections to server

public class CustomWebSocket {
    // websocket to ccyy.xyz for predicting and pairing functionality
    private static OkHttpClient mClient;
    private static CustomWebSocket myInstance;
    private CustomWebSocket() {
        // websocket to ccyy.xyz for pairing functionality
        mClient = new OkHttpClient.Builder()
                .readTimeout(3600, TimeUnit.SECONDS)
                .writeTimeout(3600, TimeUnit.SECONDS)
                .connectTimeout(3600, TimeUnit.SECONDS)
                .build();
    }

    public static CustomWebSocket getInstance() {
        if (myInstance == null) {
            myInstance = new CustomWebSocket();
        }
        return myInstance;
    }

    public OkHttpClient getClient() {
        return mClient;
    }
}

Iterator

Iterator design patten here is used to create a stream of posts, iterator helps us hide the complexity of managing the counter and the post collection. Making our code much more tidy and readable

public interface Iterator {
    public boolean hasNext();
    public Object next();
}

public interface IterableCollection {
    public Iterator createIterator();
}

/**
 * Iterator pattern, used for showing post as a stream
 */
public class PostsConcreteCollection implements IterableCollection {
    private ArrayList<HashMap<String, Object>> AllPostCollection = allPostItems;

    @Override
    public Iterator createIterator() {
        return new PostsConcreteIterator();
    }

    private class PostsConcreteIterator implements Iterator {
        int index = 0;

        /**
         * determine whether has next post
         *
         * @return True if has next post
         */
        @Override
        public boolean hasNext() {
            if (AllPostCollection != null && index < AllPostCollection.size()) {
                return true;
            }
            return false;
        }

        /**
         * if has next post,get it
         *
         * @return next post if has next, otherwise null
         */
        @Override
        public Object next() {
            if (this.hasNext()) {
                return AllPostCollection.get(index++);
            }
            return null;
        }
    }
}

Timer timer = new Timer();
timer.schedule(new MyTask(PostActivity.this), 0, 2000);

/**
 * used to give a time gap for showing new posts and show posts as a stream
 */
private class MyTask extends TimerTask {
    private Activity context;

    MyTask(Activity context) {
        this.context = context;
    }

    @Override
    public void run() {
        context.runOnUiThread(updateThread);
    }
}

Runnable updateThread = new Runnable() {
    /**
     * if has next post, add it and show, otherwise not update
     */
    @Override
    public void run() {
        if (PostIterator.hasNext()) {
            HashMap<String, Object> SinglePost = (HashMap<String, Object>) PostIterator.next();
            BufferPostList.add(SinglePost);
        }
        postAdapter = new PostAdapter(getApplicationContext(), BufferPostList);
        recyclerView.setAdapter(postAdapter);

    }

};