Reformatted code from MainActivity and set a default drawable for the server...

Reformatted code from MainActivity and set a default drawable for the server list icons whenever ic_launcher isnt available at mipmap

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

 package chat.rocket.android.activity;
 
 import android.content.Intent;
+import android.graphics.drawable.Drawable;
 import android.os.Bundle;
+import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.design.widget.Snackbar;
 import android.support.v4.app.Fragment;
@@ -26,6 +28,7 @@ import chat.rocket.android.fragment.chatroom.RoomFragment;
 import chat.rocket.android.fragment.sidebar.SidebarMainFragment;
 import chat.rocket.android.helper.KeyboardHelper;
 import chat.rocket.android.service.ConnectivityManager;
+import chat.rocket.android.service.ConnectivityManagerApi;
 import chat.rocket.android.widget.RoomToolbar;
 import chat.rocket.android.widget.helper.FrescoHelper;
 import chat.rocket.core.interactors.CanCreateRoomInteractor;
@@ -57,15 +60,16 @@ public class MainActivity extends AbstractAuthedActivity implements MainContract
     protected void onCreate(@Nullable Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
-    toolbar = (RoomToolbar) findViewById(R.id.activity_main_toolbar);
+        toolbar = findViewById(R.id.activity_main_toolbar);
         statusTicker = new StatusTicker();
-    pane = (SlidingPaneLayout) findViewById(R.id.sliding_pane);
+        pane = findViewById(R.id.sliding_pane);
         setupToolbar();
     }
 
     @Override
     protected void onResume() {
         super.onResume();
+        ConnectivityManagerApi connectivityManager = ConnectivityManager.getInstance(getApplicationContext());
         if (hostname == null || presenter == null) {
             String previousHostname = hostname;
             hostname = new RocketChatCache(getApplicationContext()).getSelectedServerHostname();
@@ -74,12 +78,12 @@ public class MainActivity extends AbstractAuthedActivity implements MainContract
             } else {
                 onHostnameUpdated();
                 if (!hostname.equalsIgnoreCase(previousHostname)) {
-          ConnectivityManager.getInstance(getApplicationContext()).resetConnectivityStateList();
-          ConnectivityManager.getInstance(getApplicationContext()).keepAliveServer();
+                    connectivityManager.resetConnectivityStateList();
+                    connectivityManager.keepAliveServer();
                 }
             }
         } else {
-      ConnectivityManager.getInstance(getApplicationContext()).keepAliveServer();
+            connectivityManager.keepAliveServer();
             presenter.bindView(this);
             presenter.loadSignedInServers(hostname);
             roomId = new RocketChatCache(getApplicationContext()).getSelectedRoomId();
@@ -107,18 +111,18 @@ public class MainActivity extends AbstractAuthedActivity implements MainContract
         if (pane != null) {
             pane.setPanelSlideListener(new SlidingPaneLayout.PanelSlideListener() {
                 @Override
-        public void onPanelSlide(View view, float v) {
+                public void onPanelSlide(@NonNull View view, float v) {
                     //Ref: ActionBarDrawerToggle#setProgress
                     toolbar.setNavigationIconProgress(v);
                 }
 
                 @Override
-        public void onPanelOpened(View view) {
+                public void onPanelOpened(@NonNull View view) {
                     toolbar.setNavigationIconVerticalMirror(true);
                 }
 
                 @Override
-        public void onPanelClosed(View view) {
+                public void onPanelClosed(@NonNull View view) {
                     toolbar.setNavigationIconVerticalMirror(false);
                     Fragment fragment = getSupportFragmentManager()
                             .findFragmentById(R.id.sidebar_fragment_container);
@@ -267,7 +271,7 @@ public class MainActivity extends AbstractAuthedActivity implements MainContract
 
     @Override
     public void showSignedInServers(List<Pair<String, Pair<String, String>>> serverList) {
-    final SlidingPaneLayout subPane = (SlidingPaneLayout) findViewById(R.id.sub_sliding_pane);
+        final SlidingPaneLayout subPane = findViewById(R.id.sub_sliding_pane);
         if (subPane != null) {
             LinearLayout serverListContainer = subPane.findViewById(R.id.server_list_bar);
             View addServerButton = subPane.findViewById(R.id.btn_add_server);
@@ -301,7 +305,13 @@ public class MainActivity extends AbstractAuthedActivity implements MainContract
 
                     newServerView.setOnClickListener(view -> changeServerIfNeeded(serverHostname));
 
-          FrescoHelper.INSTANCE.loadImage(serverButton, logoUrl, ContextCompat.getDrawable(this, R.mipmap.ic_launcher));
+                    Drawable drawable = ContextCompat.getDrawable(this, R.mipmap.ic_launcher);
+                    if (drawable == null) {
+                        int id = getResources().getIdentifier(
+                                "rocket_chat_notification", "drawable", getPackageName());
+                        drawable = ContextCompat.getDrawable(this, id);
+                    }
+                    FrescoHelper.INSTANCE.loadImage(serverButton, logoUrl, drawable);
 
                     serverListContainer.addView(newServerView);
                 }
@@ -342,18 +352,18 @@ public class MainActivity extends AbstractAuthedActivity implements MainContract
 
     //TODO: consider this class to define in layouthelper for more complicated operation.
     private static class StatusTicker {
-    public static final int STATUS_DISMISS = 0;
-    public static final int STATUS_CONNECTION_ERROR = 1;
-    public static final int STATUS_TOKEN_LOGIN = 2;
+        static final int STATUS_DISMISS = 0;
+        static final int STATUS_CONNECTION_ERROR = 1;
+        static final int STATUS_TOKEN_LOGIN = 2;
 
         private int status;
         private Snackbar snackbar;
 
-    public StatusTicker() {
+        StatusTicker() {
             status = STATUS_DISMISS;
         }
 
-    public void updateStatus(int status, Snackbar snackbar) {
+        void updateStatus(int status, Snackbar snackbar) {
             if (status == this.status) {
                 return;
             }