Feature - Realtime Database Pagination

app/src/main/AndroidManifest.xml

@@ -55,6 +55,12 @@
         <activity
             android:name=".database.realtime.RealtimeDbChatActivity"
             android:label="@string/title_realtime_database_activity" />
+
+        <!-- Realtime database paging demo -->
+        <activity
+            android:name=".database.realtime.FirebaseDbPagingActivity"
+            android:label="@string/title_paging_database_activity" />
+
         <activity
             android:name=".database.realtime.RealtimeDbChatIndexActivity"
             android:label="@string/title_realtime_database_activity" />

app/src/main/java/com/firebase/uidemo/ChooserActivity.java

@@ -32,6 +32,7 @@
 import com.firebase.uidemo.auth.AuthUiActivity;
 import com.firebase.uidemo.database.firestore.FirestoreChatActivity;
 import com.firebase.uidemo.database.firestore.FirestorePagingActivity;
+import com.firebase.uidemo.database.realtime.FirebaseDbPagingActivity;
 import com.firebase.uidemo.database.realtime.RealtimeDbChatActivity;
 import com.firebase.uidemo.storage.ImageActivity;
 
@@ -71,6 +72,7 @@ private static class ActivityChooserAdapter
                 FirestoreChatActivity.class,
                 FirestorePagingActivity.class,
                 RealtimeDbChatActivity.class,
+                FirebaseDbPagingActivity.class,
                 ImageActivity.class,
         };
 
@@ -80,6 +82,7 @@ private static class ActivityChooserAdapter
                 R.string.title_firestore_activity,
                 R.string.title_firestore_paging_activity,
                 R.string.title_realtime_database_activity,
+                R.string.title_paging_database_activity,
                 R.string.title_storage_activity
         };
 
@@ -89,6 +92,7 @@ private static class ActivityChooserAdapter
                 R.string.desc_firestore,
                 R.string.desc_firestore_paging,
                 R.string.desc_realtime_database,
+                R.string.desc_paging_database,
                 R.string.desc_storage
         };
 

app/src/main/java/com/firebase/uidemo/database/realtime/FirebaseDbPagingActivity.java

@@ -0,0 +1,161 @@
+package com.firebase.uidemo.database.realtime;
+
+import android.arch.paging.PagedList;
+import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.support.v4.widget.SwipeRefreshLayout;
+import android.support.v7.app.AppCompatActivity;
+import android.support.v7.widget.LinearLayoutManager;
+import android.support.v7.widget.RecyclerView;
+import android.util.Log;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.TextView;
+import android.widget.Toast;
+
+import com.firebase.ui.database.paging.DatabasePagingOptions;
+import com.firebase.ui.database.paging.FirebaseRecyclerPagingAdapter;
+import com.firebase.ui.database.paging.LoadingState;
+import com.firebase.uidemo.R;
+import com.google.firebase.database.DatabaseError;
+import com.google.firebase.database.FirebaseDatabase;
+import com.google.firebase.database.Query;
+
+import butterknife.BindView;
+import butterknife.ButterKnife;
+
+public class FirebaseDbPagingActivity extends AppCompatActivity {
+
+    private final String TAG = "PagingActivity";
+
+    @BindView(R.id.paging_recycler)
+    RecyclerView mRecycler;
+
+    @BindView(R.id.swipe_refresh_layout)
+    SwipeRefreshLayout mSwipeRefreshLayout;
+
+    private Query mQuery;
+
+    @Override
+    protected void onCreate(@Nullable Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_database_paging);
+        ButterKnife.bind(this);
+
+        mQuery = FirebaseDatabase.getInstance().getReference().child("posts");
+
+        setUpAdapter();
+    }
+
+    private void setUpAdapter() {
+
+        //Initialize Paging Configurations
+        PagedList.Config config = new PagedList.Config.Builder()
+                .setEnablePlaceholders(false)
+                .setPrefetchDistance(5)
+                .setPageSize(30)
+                .build();
+
+        //Initialize Firebase Paging Options
+        DatabasePagingOptions<Post> options = new DatabasePagingOptions.Builder<Post>()
+                .setLifecycleOwner(this)
+                .setQuery(mQuery, config, Post.class)
+                .build();
+
+        //Initializing Adapter
+        final FirebaseRecyclerPagingAdapter<Post, PostViewHolder> mAdapter =
+                new FirebaseRecyclerPagingAdapter<Post, PostViewHolder>(options) {
+                    @NonNull
+                    @Override
+                    public PostViewHolder onCreateViewHolder(@NonNull ViewGroup parent,
+                                                             int viewType) {
+                        View view = LayoutInflater.from(parent.getContext())
+                                .inflate(R.layout.item_post, parent, false);
+                        return new PostViewHolder(view);
+                    }
+
+                    @Override
+                    protected void onBindViewHolder(@NonNull PostViewHolder holder,
+                                                    int position,
+                                                    @NonNull Post model) {
+                        holder.bind(model);
+                    }
+
+                    @Override
+                    protected void onLoadingStateChanged(@NonNull LoadingState state) {
+                        switch (state) {
+                            case LOADING_INITIAL:
+                            case LOADING_MORE:
+                                mSwipeRefreshLayout.setRefreshing(true);
+                                break;
+
+                            case LOADED:
+                                mSwipeRefreshLayout.setRefreshing(false);
+                                break;
+
+                            case FINISHED:
+                                mSwipeRefreshLayout.setRefreshing(false);
+                                Toast.makeText(getApplicationContext(), getString(R.string.paging_finished_message), Toast.LENGTH_SHORT).show();
+                                break;
+
+                            case ERROR:
+                                retry();
+                                break;
+                        }
+                    }
+
+                    @Override
+                    protected void onError(DatabaseError databaseError) {
+                        mSwipeRefreshLayout.setRefreshing(false);
+                        Log.e(TAG, databaseError.getMessage());
+                    }
+                };
+
+        mRecycler.setLayoutManager(new LinearLayoutManager(this));
+        mRecycler.setAdapter(mAdapter);
+
+        // Reload data on swipe
+        mSwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
+            @Override
+            public void onRefresh() {
+                //Reload Data
+                mAdapter.refresh();
+            }
+        });
+    }
+
+    public static class Post {
+
+        @Nullable public String title;
+        @Nullable public String body;
+
+        public Post(){}
+
+        public Post(@Nullable String title, @Nullable String body) {
+            this.title = title;
+            this.body = body;
+        }
+    }
+
+    public static class PostViewHolder extends RecyclerView.ViewHolder {
+
+        @BindView(R.id.textViewTitle)
+        TextView mTitleView;
+
+        @BindView(R.id.textViewBody)
+        TextView mBodyView;
+
+        PostViewHolder(@NonNull View itemView) {
+            super(itemView);
+            ButterKnife.bind(this, itemView);
+        }
+
+        void bind(@NonNull Post post) {
+            mTitleView.setText(post.title);
+            mBodyView.setText(post.body);
+        }
+    }
+
+}

app/src/main/res/layout/activity_database_paging.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<android.support.v4.widget.SwipeRefreshLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/swipe_refresh_layout"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context="com.firebase.uidemo.database.realtime.FirebaseDbPagingActivity">
+
+    <android.support.v7.widget.RecyclerView
+        android:id="@+id/paging_recycler"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:layout_below="@+id/paging_loading"
+        android:clipToPadding="false"
+        android:paddingLeft="16dp"
+        android:paddingTop="8dp"
+        android:paddingRight="16dp"
+        tools:listitem="@layout/item_post" />
+
+</android.support.v4.widget.SwipeRefreshLayout>

app/src/main/res/layout/item_post.xml

@@ -0,0 +1,47 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:orientation="vertical"
+    android:layout_height="wrap_content">
+
+    <android.support.v7.widget.CardView
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginLeft="4dp"
+        android:layout_marginTop="2dp"
+        android:layout_marginRight="4dp"
+        android:layout_marginBottom="2dp"
+        android:clickable="true"
+        android:foreground="?android:selectableItemBackground"
+        app:cardElevation="2dp"
+        android:focusable="true">
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="vertical"
+            android:padding="8dp">
+
+            <TextView
+                android:id="@+id/textViewTitle"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:text="@string/post_text_title"
+                android:textColor="#000000"
+                android:textSize="18sp"
+                android:textStyle="bold" />
+
+            <TextView
+                android:id="@+id/textViewBody"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_margin="4dp"
+                android:text="@string/post_text_body"
+                android:textColor="#000000"
+                android:textSize="15sp" />
+        </LinearLayout>
+    </android.support.v7.widget.CardView>
+
+
+</LinearLayout>

app/src/main/res/values/strings.xml

@@ -6,13 +6,15 @@
     <string name="title_firestore_activity">Cloud Firestore Demo</string>
     <string name="title_firestore_paging_activity">Cloud Firestore Paging Demo</string>
     <string name="title_realtime_database_activity">Real-time database demo</string>
+    <string name="title_paging_database_activity">Paging database demo</string>
     <string name="title_storage_activity">Storage Image Demo</string>
 
     <string name="desc_auth">Demonstrates the Firebase Auth UI flow, with customization options.</string>
     <string name="desc_anonymous_upgrade">Demonstrates upgrading an anonymous account using FirebaseUI.</string>
     <string name="desc_firestore">Demonstrates using a FirestoreRecyclerAdapter to load data from Cloud Firestore into a RecyclerView for a basic chat app.</string>
     <string name="desc_firestore_paging">Demonstrates using a FirestorePagingAdapter to load/infinite scroll paged data from Cloud Firestore.</string>
     <string name="desc_realtime_database">Demonstrates using a FirebaseRecyclerAdapter to load data from Firebase Database into a RecyclerView for a basic chat app.</string>
+    <string name="desc_paging_database">Demonstrates using a FirebaseRecyclerPagingAdapter to load/infinite scroll paged data from Firebase Database.</string>
     <string name="desc_storage">Demonstrates displaying an image from Cloud Storage using Glide.</string>
 
     <!-- Auth UI -->
@@ -118,6 +120,8 @@
     <string name="start_chatting">No messages. Start chatting at the bottom!</string>
     <string name="signing_in">Signing in…</string>
     <string name="signed_in">Signed In</string>
+    <string name="post_text_title">Title</string>
+    <string name="post_text_body">Body</string>
     <string name="anonymous_auth_failed_msg">
         Anonymous authentication failed, various components of the demo will not work.
         Make sure your device is online and that Anonymous Auth is configured in your Firebase project
@@ -126,4 +130,5 @@
 
     <string name="menu_add_data">Add Data</string>
     <string name="hint_message">Say something…</string>
+    <string name="paging_finished_message">Reached End of List</string>
 </resources>

database/README.md

@@ -202,7 +202,7 @@ protected void onStop() {
 If you don't want to manually start/stop listening you can use
 [Android Architecture Components][arch-components] to automatically manage the lifecycle of the
 `FirebaseRecyclerAdapter`. Pass a `LifecycleOwner` to
-`FirebaseRecyclerAdapter.Builder#setLifecycleOwner(...)` and FirebaseUI will automatically
+`FirebaseRecyclerOptions.Builder#setLifecycleOwner(...)` and FirebaseUI will automatically
 start and stop listening in `onStart()` and `onStop()`.
 
 ### Data and error events

database/build.gradle.kts

@@ -4,6 +4,14 @@ android {
     defaultConfig {
         testInstrumentationRunner = "android.support.test.runner.AndroidJUnitRunner"
     }
+
+    buildTypes {
+        named("release").configure {
+            postprocessing {
+                consumerProguardFiles("proguard-rules.pro")
+            }
+        }
+    }
 }
 
 dependencies {
@@ -12,6 +20,8 @@ dependencies {
 
     api(Config.Libs.Support.v4)
     api(Config.Libs.Support.recyclerView)
+
+    compileOnly(Config.Libs.Arch.paging)
     annotationProcessor(Config.Libs.Arch.compiler)
 
     androidTestImplementation(Config.Libs.Test.junit)

database/proguard-rules.pro

@@ -0,0 +1 @@
+-dontwarn com.firebase.ui.database.paging.**