Added EnsiChatActivity to avoid code duplication for service connection.

app/src/main/scala/com/nutomic/ensichat/activities/EnsiChatActivity.scala

@@ -0,0 +1,65 @@
+package com.nutomic.ensichat.activities
+
+import android.app.Activity
+import android.content.{ComponentName, Context, Intent, ServiceConnection}
+import android.os.{Bundle, IBinder}
+import com.nutomic.ensichat.bluetooth.{ChatService, ChatServiceBinder}
+
+/**
+ * Connects to [[ChatService]] and provides access to it.
+ */
+class EnsiChatActivity extends Activity with ServiceConnection {
+
+  var chatService: Option[ChatService] = None
+
+  var listeners: List[() => Unit] = List.empty
+
+  /**
+   * Starts service and connects to it.
+   */
+  override def onCreate(savedInstanceState: Bundle): Unit = {
+    super.onCreate(savedInstanceState)
+    startService(new Intent(this, classOf[ChatService]))
+    bindService(new Intent(this, classOf[ChatService]), this, Context.BIND_AUTO_CREATE)
+  }
+
+  /**
+   * Unbinds service.
+   */
+  override def onDestroy(): Unit = {
+    super.onDestroy()
+    unbindService(this)
+  }
+
+  /**
+   * Calls all listeners registered with [[runOnServiceConnected]].
+   *
+   * Clears the list containing them.
+   */
+  override def onServiceConnected(componentName: ComponentName, iBinder: IBinder): Unit = {
+    val binder = iBinder.asInstanceOf[ChatServiceBinder]
+    chatService = Option(binder.getService)
+    listeners.foreach(_())
+    listeners = List.empty
+  }
+
+  override def onServiceDisconnected(componentName: ComponentName) =
+    chatService = null
+
+  /**
+   * Calls l as soon as [[ChatService]] first becomes available.
+   */
+  def runOnServiceConnected(l: () => Unit): Unit =
+    chatService match {
+      case Some(s) => l()
+      case None => listeners :+= l
+    }
+
+  /**
+   * Returns the [[ChatService]].
+   *
+   * Should only be called after [[runOnServiceConnected]] callback was called.
+   */
+  def service = chatService.get
+
+}

app/src/main/scala/com/nutomic/ensichat/activities/MainActivity.scala

@@ -12,7 +12,7 @@ import com.nutomic.ensichat.fragments.{ChatFragment, ContactsFragment}
 /**
  * Main activity, entry point for app start.
  */
-class MainActivity extends Activity {
+class MainActivity extends EnsiChatActivity {
 
   private val RequestSetDiscoverable = 1
 
@@ -26,7 +26,6 @@ class MainActivity extends Activity {
   override def onCreate(savedInstanceState: Bundle): Unit = {
     super.onCreate(savedInstanceState)
     setContentView(R.layout.activity_main)
-    startService(new Intent(this, classOf[ChatService]))
 
     val intent: Intent = new
         Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE)

app/src/main/scala/com/nutomic/ensichat/fragments/ChatFragment.scala

@@ -11,6 +11,7 @@ import android.view.{KeyEvent, LayoutInflater, View, ViewGroup}
 import android.widget.TextView.OnEditorActionListener
 import android.widget._
 import com.nutomic.ensichat.R
+import com.nutomic.ensichat.activities.EnsiChatActivity
 import com.nutomic.ensichat.bluetooth.ChatService.OnMessageReceivedListener
 import com.nutomic.ensichat.bluetooth.{ChatService, ChatServiceBinder, Device}
 import com.nutomic.ensichat.messages.{Message, TextMessage}
@@ -41,21 +42,21 @@ class ChatFragment extends ListFragment with OnClickListener
 
   private var adapter: ArrayAdapter[TextMessage] = _
 
-  private final val mChatServiceConnection: ServiceConnection = new ServiceConnection {
+  override def onActivityCreated(savedInstanceState: Bundle): Unit = {
-    override def onServiceConnected(componentName: ComponentName, iBinder: IBinder): Unit = {
+    super.onActivityCreated(savedInstanceState)
-      val binder: ChatServiceBinder = iBinder.asInstanceOf[ChatServiceBinder]
+
-      chatService = binder.getService
+    val activity = getActivity.asInstanceOf[EnsiChatActivity]
+    activity.runOnServiceConnected(() => {
+      chatService = activity.service
+
       // Read local device ID from service,
       adapter = new MessagesAdapter(getActivity, chatService.localDeviceId)
       chatService.registerMessageListener(device, ChatFragment.this)
+
       if (listView != null) {
         listView.setAdapter(adapter)
       }
-    }
+    })
-
-    override def onServiceDisconnected(componentName: ComponentName): Unit = {
-      chatService = null
-    }
   }
 
   override def onCreateView(inflater: LayoutInflater, container: ViewGroup,
@@ -81,9 +82,6 @@ class ChatFragment extends ListFragment with OnClickListener
   override def onCreate(savedInstanceState: Bundle): Unit = {
     super.onCreate(savedInstanceState)
 
-    getActivity.bindService(new Intent(getActivity, classOf[ChatService]),
-      mChatServiceConnection, Context.BIND_AUTO_CREATE)
-
     if (savedInstanceState != null) {
       device = new Device.ID(savedInstanceState.getString("device"))
     }
@@ -94,11 +92,6 @@ class ChatFragment extends ListFragment with OnClickListener
     outState.putString("device", device.toString)
   }
 
-  override def onDestroy(): Unit = {
-    super.onDestroy()
-    getActivity.unbindService(mChatServiceConnection)
-  }
-
   /**
    * Send message if send button was clicked.
    */

app/src/main/scala/com/nutomic/ensichat/fragments/ContactsFragment.scala

@@ -6,52 +6,37 @@ import android.os.{Bundle, IBinder}
 import android.view._
 import android.widget.{ArrayAdapter, ListView}
 import com.nutomic.ensichat.R
-import com.nutomic.ensichat.activities.MainActivity
+import com.nutomic.ensichat.activities.{EnsiChatActivity, MainActivity}
 import com.nutomic.ensichat.bluetooth.{ChatService, ChatServiceBinder, Device}
-import com.nutomic.ensichat.util.DevicesAdapter
+import com.nutomic.ensichat.util.{MessagesAdapter, DevicesAdapter}
 
 /**
  * Lists all nearby, connected devices.
  */
 class ContactsFragment extends ListFragment with ChatService.OnConnectionChangedListener {
 
-  private var chatService: ChatService = _
+  private lazy val adapter = new DevicesAdapter(getActivity)
 
-  private final val ChatServiceConnection: ServiceConnection = new ServiceConnection {
+  override def onActivityCreated(savedInstanceState: Bundle): Unit = {
-    override def onServiceConnected(componentName: ComponentName, iBinder: IBinder): Unit = {
+    super.onActivityCreated(savedInstanceState)
-      val binder: ChatServiceBinder = iBinder.asInstanceOf[ChatServiceBinder]
-      chatService = binder.getService
-      chatService.registerConnectionListener(ContactsFragment.this)
-    }
 
-    override def onServiceDisconnected(componentName: ComponentName): Unit = {
+    val activity = getActivity.asInstanceOf[EnsiChatActivity]
-      chatService = null
+    activity.runOnServiceConnected(() => {
+      activity.service.registerConnectionListener(ContactsFragment.this)
+    })
   }
-  }
-
-  private var adapter: ArrayAdapter[Device] = _
 
   override def onCreateView(inflater: LayoutInflater, container: ViewGroup,
-        savedInstanceState: Bundle): View = {
+        savedInstanceState: Bundle): View =
-    val view: View =  inflater.inflate(R.layout.fragment_contacts, container, false)
+    inflater.inflate(R.layout.fragment_contacts, container, false)
-    view
-  }
 
   override def onCreate(savedInstanceState: Bundle): Unit = {
     super.onCreate(savedInstanceState)
 
-    adapter = new DevicesAdapter(getActivity)
     setListAdapter(adapter)
-    getActivity.bindService(new Intent(getActivity, classOf[ChatService]),
-      ChatServiceConnection, Context.BIND_AUTO_CREATE)
     setHasOptionsMenu(true)
   }
 
-  override def onDestroy(): Unit = {
-    super.onDestroy()
-    getActivity.unbindService(ChatServiceConnection)
-  }
-
   override def onCreateOptionsMenu(menu: Menu, inflater: MenuInflater): Unit = {
     super.onCreateOptionsMenu(menu, inflater)
     inflater.inflate(R.menu.main, menu)
@@ -87,8 +72,7 @@ class ContactsFragment extends ListFragment with ChatService.OnConnectionChanged
   /**
    * Opens a chat with the clicked device.
    */
-  override def onListItemClick(l: ListView, v: View, position: Int, id: Long): Unit = {
+  override def onListItemClick(l: ListView, v: View, position: Int, id: Long): Unit =
     getActivity.asInstanceOf[MainActivity].openChat(adapter.getItem(position).id)
-  }
 
 }