implement message view stub.

app/src/main/java/chat/rocket/android/activity/AbstractAuthedActivity.java

 package chat.rocket.android.activity;
 
 import android.content.SharedPreferences;
+import android.os.Bundle;
 import chat.rocket.android.LaunchUtil;
 import chat.rocket.android.RocketChatCache;
 import chat.rocket.android.model.ServerConfig;
 import chat.rocket.android.realm_helper.RealmListObserver;
 import chat.rocket.android.realm_helper.RealmStore;
 import chat.rocket.android.service.RocketChatService;
+import icepick.State;
 
 abstract class AbstractAuthedActivity extends AbstractFragmentActivity {
   private RealmListObserver<ServerConfig> unconfiguredServersObserver =
@@ -19,8 +21,8 @@ abstract class AbstractAuthedActivity extends AbstractFragmentActivity {
             }
           });
 
-  protected String serverConfigId;
-  protected String roomId;
+  @State protected String serverConfigId;
+  @State protected String roomId;
 
   SharedPreferences.OnSharedPreferenceChangeListener preferenceChangeListener =
       (sharedPreferences, key) -> {
@@ -67,11 +69,7 @@ abstract class AbstractAuthedActivity extends AbstractFragmentActivity {
     onRoomIdUpdated();
   }
 
-  protected void onServerConfigIdUpdated() {
-    RocketChatCache.get(this).edit()
-        .remove(RocketChatCache.KEY_SELECTED_ROOM_ID)
-        .apply();
-  }
+  protected void onServerConfigIdUpdated() {}
 
   protected void onRoomIdUpdated() {}
 
@@ -93,4 +91,8 @@ abstract class AbstractAuthedActivity extends AbstractFragmentActivity {
     unconfiguredServersObserver.unsub();
     super.onPause();
   }
+
+  @Override protected void onSaveInstanceState(Bundle outState) {
+    super.onSaveInstanceState(outState);
+  }
 }

app/src/main/java/chat/rocket/android/activity/MainActivity.java

@@ -29,7 +29,9 @@ public class MainActivity extends AbstractAuthedActivity {
     setContentView(R.layout.activity_main);
 
     setupSidebar();
-    showFragment(new HomeFragment());
+    if (roomId == null) {
+      showFragment(new HomeFragment());
+    }
   }
 
   private void setupSidebar() {

app/src/main/java/chat/rocket/android/fragment/chatroom/RoomFragment.java

@@ -2,14 +2,22 @@ package chat.rocket.android.fragment.chatroom;
 
 import android.os.Bundle;
 import android.support.annotation.Nullable;
+import android.support.v7.widget.LinearLayoutManager;
+import android.support.v7.widget.RecyclerView;
 import chat.rocket.android.R;
 import chat.rocket.android.helper.LogcatIfError;
+import chat.rocket.android.layouthelper.chatroom.MessageListAdapter;
 import chat.rocket.android.model.SyncState;
+import chat.rocket.android.model.ddp.Message;
 import chat.rocket.android.model.ddp.RoomSubscription;
 import chat.rocket.android.model.internal.LoadMessageProcedure;
 import chat.rocket.android.realm_helper.RealmHelper;
+import chat.rocket.android.realm_helper.RealmModelListView;
 import chat.rocket.android.realm_helper.RealmObjectObserver;
 import chat.rocket.android.realm_helper.RealmStore;
+import io.realm.Realm;
+import io.realm.RealmResults;
+import io.realm.Sort;
 import org.json.JSONObject;
 
 /**
@@ -45,6 +53,8 @@ public class RoomFragment extends AbstractChatRoomFragment {
     roomObserver = realmHelper
         .createObjectObserver(realm -> realm.where(RoomSubscription.class).equalTo("rid", roomId))
         .setOnUpdateListener(this::onRenderRoom);
+
+    initialRequest();
   }
 
   @Override protected int getLayout() {
@@ -52,8 +62,24 @@ public class RoomFragment extends AbstractChatRoomFragment {
   }
 
   @Override protected void onSetupView() {
+    RealmModelListView listView = (RealmModelListView) rootView.findViewById(R.id.listview);
+
+    realmHelper.bindListView(listView,
+        realm -> realm.where(Message.class)
+            .equalTo("rid", roomId)
+            .findAllSorted("ts", Sort.DESCENDING),
+        MessageListAdapter::new);
+
+    RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getContext(),
+        LinearLayoutManager.VERTICAL, true);
+    listView.setLayoutManager(layoutManager);
+  }
+
+  private void onRenderRoom(RoomSubscription roomSubscription) {
+    activityToolbar.setTitle(roomSubscription.getName());
+  }
 
-    // TODO: just a sample!!
+  private void initialRequest() {
     realmHelper.executeTransaction(realm -> {
       realm.createOrUpdateObjectFromJson(LoadMessageProcedure.class, new JSONObject()
           .put("roomId", roomId)
@@ -64,8 +90,8 @@ public class RoomFragment extends AbstractChatRoomFragment {
     }).continueWith(new LogcatIfError());
   }
 
-  private void onRenderRoom(RoomSubscription roomSubscription) {
-    activityToolbar.setTitle(roomSubscription.getName());
+  private RealmResults<Message> queryItems(Realm realm) {
+    return realm.where(Message.class).equalTo("rid", roomId).findAllSorted("ts");
   }
 
   @Override public void onResume() {

app/src/main/java/chat/rocket/android/layouthelper/chatroom/MessageListAdapter.java

+package chat.rocket.android.layouthelper.chatroom;
+
+import android.content.Context;
+import android.view.View;
+import chat.rocket.android.model.ddp.Message;
+import chat.rocket.android.realm_adapter.RealmModelListAdapter;
+
+/**
+ * message list adapter for chat room.
+ */
+public class MessageListAdapter extends RealmModelListAdapter<Message, MessageViewHolder> {
+
+  public MessageListAdapter(Context context) {
+    super(context);
+  }
+
+  @Override protected int getItemViewType(Message model) {
+    return 0;
+  }
+
+  @Override protected int getLayout(int viewType) {
+    return android.R.layout.simple_list_item_1;
+  }
+
+  @Override protected MessageViewHolder onCreateRealmModelViewHolder(int viewType, View itemView) {
+    return new MessageViewHolder(itemView);
+  }
+}

app/src/main/java/chat/rocket/android/layouthelper/chatroom/MessageViewHolder.java

+package chat.rocket.android.layouthelper.chatroom;
+
+import android.graphics.Color;
+import android.view.View;
+import android.widget.TextView;
+import chat.rocket.android.model.ddp.Message;
+import chat.rocket.android.realm_adapter.RealmModelViewHolder;
+
+/**
+ */
+public class MessageViewHolder extends RealmModelViewHolder<Message> {
+  private TextView text;
+  public MessageViewHolder(View itemView) {
+    super(itemView);
+    text = (TextView) itemView.findViewById(android.R.id.text1);
+  }
+
+  public void bind(Message message) {
+    text.setText(message.getMsg());
+    text.setTextColor(Color.BLACK);
+  }
+}

app/src/main/java/chat/rocket/android/service/observer/LoadMessageProcedureObserver.java

@@ -64,8 +64,7 @@ public class LoadMessageProcedureObserver extends AbstractModelObserver<LoadMess
                       .put("roomId", roomId)
                       .put("syncstate", SyncState.SYNCED)
                       .put("timestamp", lastTs)
-                      .put("hasNext", lastTs > 0))
-              );
+                      .put("hasNext", lastTs > 0)));
             })
     ).continueWithTask(task -> {
       if (task.isFaulted()) {

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

@@ -3,8 +3,8 @@
     android:layout_width="match_parent"
     android:layout_height="match_parent">
 
-  <android.support.v7.widget.RecyclerView
-      android:id="@+id/recyclerview"
+  <chat.rocket.android.realm_helper.RealmModelListView
+      android:id="@+id/listview"
       android:layout_width="match_parent"
       android:layout_height="match_parent"
       />

realm-helpers/build.gradle

@@ -36,4 +36,5 @@ dependencies {
   compile rootProject.ext.supportAnnotations
   compile rootProject.ext.supportAppCompat
   compile rootProject.ext.supportDesign
+  compile 'io.realm:android-adapters:1.4.0'
 }

realm-helpers/src/main/java/chat/rocket/android/realm_adapter/RealmModelListAdapter.java

+package chat.rocket.android.realm_adapter;
+
+import android.content.Context;
+import android.support.annotation.LayoutRes;
+import android.view.View;
+import android.view.ViewGroup;
+import io.realm.Realm;
+import io.realm.RealmObject;
+import io.realm.RealmRecyclerViewAdapter;
+import io.realm.RealmResults;
+
+public abstract class RealmModelListAdapter<T extends RealmObject,
+    VH extends RealmModelViewHolder<T>> extends RealmRecyclerViewAdapter<T, VH> {
+
+  public interface Query<T extends RealmObject> {
+    RealmResults<T> queryItems(Realm realm);
+  }
+
+  public interface Constructor<T extends RealmObject, VH extends RealmModelViewHolder<T>> {
+    RealmModelListAdapter<T, VH> getNewInstance(Context context);
+  }
+
+  public RealmModelListAdapter(Context context) {
+    super(context, null, true);
+  }
+
+  protected abstract int getItemViewType(T model);
+
+  protected abstract @LayoutRes int getLayout(int viewType);
+
+  protected abstract VH onCreateRealmModelViewHolder(int viewType, View itemView);
+
+  @Override public final int getItemViewType(int position) {
+    return getItemViewType(getItem(position));
+  }
+
+  @Override public VH onCreateViewHolder(ViewGroup parent, int viewType) {
+    View itemView = inflater.inflate(getLayout(viewType), parent, false);
+    return onCreateRealmModelViewHolder(viewType, itemView);
+  }
+
+  @Override public void onBindViewHolder(VH holder, int position) {
+    holder.bind(getItem(position));
+  }
+}

realm-helpers/src/main/java/chat/rocket/android/realm_adapter/RealmModelViewholder.java

+package chat.rocket.android.realm_adapter;
+
+import android.support.v7.widget.RecyclerView;
+import android.view.View;
+import io.realm.RealmObject;
+
+public abstract class RealmModelViewHolder<T extends RealmObject> extends RecyclerView.ViewHolder {
+
+  public RealmModelViewHolder(View itemView) {
+    super(itemView);
+  }
+
+  public abstract void bind(T model);
+}

realm-helpers/src/main/java/chat/rocket/android/realm_helper/AbstractRealmResultsObserver.java

@@ -32,7 +32,7 @@ abstract class AbstractRealmResultsObserver<T extends RealmObject> {
   }
 
   public void keepalive() {
-    if (realm == null || realm.isClosed()) {
+    if (realm == null || realm.isClosed() || !results.isValid()) {
       unsub();
       sub();
     }
@@ -41,7 +41,9 @@ abstract class AbstractRealmResultsObserver<T extends RealmObject> {
   public void unsub() {
     try {
       if (results != null) {
-        results.removeChangeListener(listener);
+        if (results.isValid()) {
+          results.removeChangeListener(listener);
+        }
         results = null;
       }
       if (realm != null && !realm.isClosed()) {

realm-helpers/src/main/java/chat/rocket/android/realm_helper/RealmHelper.java

@@ -3,6 +3,8 @@ package chat.rocket.android.realm_helper;
 import android.os.Looper;
 import bolts.Task;
 import bolts.TaskCompletionSource;
+import chat.rocket.android.realm_adapter.RealmModelListAdapter;
+import chat.rocket.android.realm_adapter.RealmModelViewHolder;
 import io.realm.Realm;
 import io.realm.RealmConfiguration;
 import io.realm.RealmObject;
@@ -168,4 +170,13 @@ public class RealmHelper {
       RealmObjectObserver.Query<T> query) {
     return new RealmObjectObserver<T>(this, query);
   }
+
+  public <T extends RealmObject, VH extends RealmModelViewHolder<T>> void bindListView(
+      RealmModelListView listView,
+      RealmModelListAdapter.Query<T> query,
+      RealmModelListAdapter.Constructor<T, VH> constructor) {
+    if (listView != null) {
+      listView.setup(this, query, constructor);
+    }
+  }
 }

realm-helpers/src/main/java/chat/rocket/android/realm_helper/RealmModelListView.java

+package chat.rocket.android.realm_helper;
+
+import android.content.Context;
+import android.support.v7.widget.RecyclerView;
+import android.util.AttributeSet;
+import android.view.View;
+import chat.rocket.android.realm_adapter.RealmModelListAdapter;
+import chat.rocket.android.realm_adapter.RealmModelViewHolder;
+import io.realm.Realm;
+import io.realm.RealmObject;
+import io.realm.RealmResults;
+
+public class RealmModelListView extends RecyclerView {
+  private Realm realm;
+
+  public RealmModelListView(Context context) {
+    super(context);
+  }
+
+  public RealmModelListView(Context context, AttributeSet attrs) {
+    super(context, attrs);
+  }
+
+  public RealmModelListView(Context context, AttributeSet attrs, int defStyleAttr) {
+    super(context, attrs, defStyleAttr);
+  }
+
+  /*package*/ <T extends RealmObject, VH extends RealmModelViewHolder<T>> void setup(
+      final RealmHelper realmHelper,
+      final RealmModelListAdapter.Query<T> query,
+      final RealmModelListAdapter.Constructor<T, VH> constructor) {
+    addOnAttachStateChangeListener(new OnAttachStateChangeListener() {
+      @Override public void onViewAttachedToWindow(View view) {
+        realm = realmHelper.instance();
+        RealmResults<T> results = query.queryItems(realm);
+        RealmModelListAdapter<T, VH> adapter = constructor.getNewInstance(view.getContext());
+        adapter.updateData(results);
+        setAdapter(adapter);
+      }
+
+      @Override public void onViewDetachedFromWindow(View view) {
+        setAdapter(null);
+        if (realm != null && !realm.isClosed()) {
+          realm.close();
+        }
+      }
+    });
+  }
+
+  // just for preventing from unexpected overriding.
+  @Override public final void setAdapter(Adapter adapter) {
+    super.setAdapter(adapter);
+  }
+}