Example Communication between Activity and Service using Messaging

Question

I couldn t find any examples of how to send messages between an activity and a service  and I have spent far too many hours figuring this out  Here is an example project for others to reference   This example allows you to start or stop a service directly  and separately bind unbind from the service  When the service is running  it increments a number at 10 nbsp Hz  If the activity is bound to the Service  it will display the current value  Data is transferred as an Integer and as a String so you can see how to do that two different ways  There are also buttons in the activity to send messages to the service  changes the increment-by value    Screenshot     AndroidManifest xml    lt  xml version  1 0  encoding  utf-8   gt   lt manifest xmlns android  http   schemas android com apk res android        package  com exampleservice        android versionCode  1        android versionName  1 0  gt       lt application android icon   drawable icon  android label   string app name  gt           lt activity android name   MainActivity                    android label   string app name  gt               lt intent-filter gt                   lt action android name  android intent action MAIN    gt                   lt category android name  android intent category LAUNCHER    gt               lt  intent-filter gt           lt  activity gt       lt service android name   MyService  gt  lt  service gt       lt  application gt       lt uses-sdk android minSdkVersion  8    gt   lt  manifest gt    res values strings xml    lt  xml version  1 0  encoding  utf-8   gt   lt resources gt       lt string name  app name  gt ExampleService lt  string gt       lt string name  service started  gt Example Service started lt  string gt       lt string name  service label  gt Example Service Label lt  string gt   lt  resources gt    res layout main xml       lt RelativeLayout     android id    id RelativeLayout01      android layout width  fill parent      android layout height  wrap content   gt        lt Button         android id    id btnStart          android layout width  wrap content          android layout height  wrap content          android text  Start Service   gt       lt  Button gt        lt Button         android id    id btnStop          android layout width  wrap content          android layout height  wrap content          android layout alignParentRight  true          android text  Stop Service   gt       lt  Button gt   lt  RelativeLayout gt    lt RelativeLayout     android id    id RelativeLayout02      android layout width  fill parent      android layout height  wrap content   gt        lt Button         android id    id btnBind          android layout width  wrap content          android layout height  wrap content          android text  Bind to Service   gt       lt  Button gt        lt Button         android id    id btnUnbind          android layout width  wrap content          android layout height  wrap content          android layout alignParentRight  true          android text  Unbind from Service   gt       lt  Button gt   lt  RelativeLayout gt    lt TextView     android id    id textStatus      android layout width  fill parent      android layout height  wrap content      android text  Status Goes Here      android textSize  24sp    gt    lt TextView     android id    id textIntValue      android layout width  fill parent      android layout height  wrap content      android text  Integer Value Goes Here      android textSize  24sp    gt    lt TextView     android id    id textStrValue      android layout width  fill parent      android layout height  wrap content      android text  String Value Goes Here      android textSize  24sp    gt    lt RelativeLayout     android id    id RelativeLayout03      android layout width  fill parent      android layout height  wrap content   gt        lt Button         android id    id btnUpby1          android layout width  wrap content          android layout height  wrap content          android text  Increment by 1   gt       lt  Button gt        lt Button         android id    id btnUpby10          android layout width  wrap content          android layout height  wrap content          android layout alignParentRight  true          android text  Increment by 10   gt       lt  Button gt   lt  RelativeLayout gt      src com exampleservice MainActivity java   package com exampleservice   import android app Activity  import android content ComponentName  import android content Context  import android content Intent  import android content ServiceConnection  import android os Bundle  import android os Handler  import android os IBinder  import android os Message  import android os Messenger  import android os RemoteException  import android util Log  import android view View  import android view View OnClickListener  import android widget Button  import android widget TextView   public class MainActivity extends Activity       Button btnStart  btnStop  btnBind  btnUnbind  btnUpby1  btnUpby10      TextView textStatus  textIntValue  textStrValue      Messenger mService   null      boolean mIsBound      final Messenger mMessenger   new Messenger new IncomingHandler          class IncomingHandler extends Handler            Override         public void handleMessage Message msg                switch  msg what                case MyService MSG SET INT VALUE                  textIntValue setText  Int Message      msg arg1                   break              case MyService MSG SET STRING VALUE                  String str1   msg getData   getString  str1                    textStrValue setText  Str Message      str1                   break              default                  super handleMessage msg                                     private ServiceConnection mConnection   new ServiceConnection             public void onServiceConnected ComponentName className  IBinder service                mService   new Messenger service               textStatus setText  Attached                 try                   Message msg   Message obtain null  MyService MSG REGISTER CLIENT                   msg replyTo   mMessenger                  mService send msg                             catch  RemoteException e                       In this case the service has crashed before we could even do anything with it                                  public void onServiceDisconnected ComponentName className                   This is called when the connection with the service has been unexpectedly disconnected - process crashed              mService   null              textStatus setText  Disconnected                            Override     public void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout main           btnStart    Button findViewById R id btnStart           btnStop    Button findViewById R id btnStop           btnBind    Button findViewById R id btnBind           btnUnbind    Button findViewById R id btnUnbind           textStatus    TextView findViewById R id textStatus           textIntValue    TextView findViewById R id textIntValue           textStrValue    TextView findViewById R id textStrValue           btnUpby1    Button findViewById R id btnUpby1           btnUpby10    Button findViewById R id btnUpby10            btnStart setOnClickListener btnStartListener           btnStop setOnClickListener btnStopListener           btnBind setOnClickListener btnBindListener           btnUnbind setOnClickListener btnUnbindListener           btnUpby1 setOnClickListener btnUpby1Listener           btnUpby10 setOnClickListener btnUpby10Listener            restoreMe savedInstanceState            CheckIfServiceIsRunning                Override     protected void onSaveInstanceState Bundle outState            super onSaveInstanceState outState           outState putString  textStatus   textStatus getText   toString             outState putString  textIntValue   textIntValue getText   toString             outState putString  textStrValue   textStrValue getText   toString               private void restoreMe Bundle state            if  state  null                textStatus setText state getString  textStatus                 textIntValue setText state getString  textIntValue                 textStrValue setText state getString  textStrValue                         private void CheckIfServiceIsRunning               If the service is running when the activity starts  we want to automatically bind to it          if  MyService isRunning                  doBindService                         private OnClickListener btnStartListener   new OnClickListener             public void onClick View v               startService new Intent MainActivity this  MyService class                         private OnClickListener btnStopListener   new OnClickListener             public void onClick View v               doUnbindService                stopService new Intent MainActivity this  MyService class                         private OnClickListener btnBindListener   new OnClickListener             public void onClick View v               doBindService                         private OnClickListener btnUnbindListener   new OnClickListener             public void onClick View v               doUnbindService                         private OnClickListener btnUpby1Listener   new OnClickListener             public void onClick View v               sendMessageToService 1                        private OnClickListener btnUpby10Listener   new OnClickListener             public void onClick View v               sendMessageToService 10                        private void sendMessageToService int intvaluetosend            if  mIsBound                if  mService    null                    try                       Message msg   Message obtain null  MyService MSG SET INT VALUE  intvaluetosend  0                       msg replyTo   mMessenger                      mService send msg                                     catch  RemoteException e                                                          void doBindService             bindService new Intent this  MyService class   mConnection  Context BIND AUTO CREATE           mIsBound   true          textStatus setText  Binding               void doUnbindService             if  mIsBound                   If we have received the service  and hence registered with it  then now is the time to unregister              if  mService    null                    try                       Message msg   Message obtain null  MyService MSG UNREGISTER CLIENT                       msg replyTo   mMessenger                      mService send msg                                     catch  RemoteException e                           There is nothing special we need to do if the service has crashed                                                 Detach our existing connection              unbindService mConnection               mIsBound   false              textStatus setText  Unbinding                           Override     protected void onDestroy             super onDestroy            try               doUnbindService                      catch  Throwable t                Log e  MainActivity    Failed to unbind from the service   t                       src com exampleservice MyService java   package com exampleservice   import java util ArrayList  import java util Timer  import java util TimerTask   import android app Notification  import android app NotificationManager  import android app PendingIntent  import android app Service  import android content Intent  import android os Bundle  import android os Handler  import android os IBinder  import android os Message  import android os Messenger  import android os RemoteException  import android util Log   public class MyService extends Service       private NotificationManager nm      private Timer timer   new Timer        private int counter   0  incrementby   1      private static boolean isRunning   false       ArrayList lt Messenger gt  mClients   new ArrayList lt Messenger gt        Keeps track of all current registered clients      int mValue   0     Holds last value set by a client      static final int MSG REGISTER CLIENT   1      static final int MSG UNREGISTER CLIENT   2      static final int MSG SET INT VALUE   3      static final int MSG SET STRING VALUE   4      final Messenger mMessenger   new Messenger new IncomingHandler        Target we publish for clients to send messages to IncomingHandler         Override     public IBinder onBind Intent intent            return mMessenger getBinder              class IncomingHandler extends Handler      Handler of incoming messages from clients           Override         public void handleMessage Message msg                switch  msg what                case MSG REGISTER CLIENT                  mClients add msg replyTo                   break              case MSG UNREGISTER CLIENT                  mClients remove msg replyTo                   break              case MSG SET INT VALUE                  incrementby   msg arg1                  break              default                  super handleMessage msg                                     private void sendMessageToUI int intvaluetosend            for  int i mClients size  -1  i gt  0  i--                try                      Send data as an Integer                 mClients get i  send Message obtain null  MSG SET INT VALUE  intvaluetosend  0                       Send data as a String                 Bundle b   new Bundle                    b putString  str1    ab    intvaluetosend    cd                    Message msg   Message obtain null  MSG SET STRING VALUE                   msg setData b                   mClients get i  send msg                              catch  RemoteException e                       The client is dead  Remove it from the list  we are going through the list from back to front so this is safe to do inside the loop                  mClients remove i                                       Override     public void onCreate             super onCreate            Log i  MyService    Service Started             showNotification            timer scheduleAtFixedRate new TimerTask    public void run    onTimerTick       0  100L           isRunning   true            private void showNotification             nm    NotificationManager getSystemService NOTIFICATION SERVICE              In this sample  we ll use the same text for the ticker and the expanded notification         CharSequence text   getText R string service started              Set the icon  scrolling text and timestamp         Notification notification   new Notification R drawable icon  text  System currentTimeMillis                The PendingIntent to launch our activity if the user selects this notification         PendingIntent contentIntent   PendingIntent getActivity this  0  new Intent this  MainActivity class   0              Set the info for the views that show in the notification panel          notification setLatestEventInfo this  getText R string service label   text  contentIntent              Send the notification             We use a layout id because it is a unique number   We use it later to cancel          nm notify R string service started  notification              Override     public int onStartCommand Intent intent  int flags  int startId            Log i  MyService    Received start id     startId          intent           return START STICKY     run until explicitly stopped             public static boolean isRunning                 return isRunning              private void onTimerTick             Log i  TimerTick    Timer doing work     counter           try               counter    incrementby              sendMessageToUI counter                      catch  Throwable t      you should always ultimately catch all exceptions in timer tasks              Log e  TimerTick    Timer Tick Failed    t                         Override     public void onDestroy             super onDestroy            if  timer    null   timer cancel             counter 0          nm cancel R string service started      Cancel the persistent notification          Log i  MyService    Service Stopped             isRunning   false

User · Answer

Note  You don t need to check if your service is running  CheckIfServiceIsRunning    because bindService   will start it if it isn t running   Also  if you rotate the phone you don t want it to bindService   again  because onCreate   will be called again  Be sure to define onConfigurationChanged   to prevent this

User · Answer

For sending data to a service you can use   Intent intent   new Intent getApplicationContext    YourService class   intent putExtra  SomeData   ItValue    startService intent     And after in service in onStartCommand   get data from intent   For sending data or event from a service to an application  for one or more activities    private void sendBroadcastMessage String intentFilterName  int arg1  String extraKey        Intent intent   new Intent intentFilterName       if  arg1    -1  amp  amp  extraKey    null            intent putExtra extraKey  arg1             sendBroadcast intent       This method is calling from your service  You can simply send data for your Activity   private void someTaskInYourService           For example you downloading from server 1000 files     for int i   0  i  lt  1000  i              Thread sleep 5000     5 seconds  Catch in try-catch block         sendBroadCastMessage Events UPDATE DOWNLOADING PROGRESSBAR  i 0  up download progress            For receiving an event with data  create and register method registerBroadcastReceivers   in your activity   private void registerBroadcastReceivers        broadcastReceiver   new BroadcastReceiver              Override         public void onReceive Context context  Intent intent                int arg1   intent getIntExtra  up download progress  0               progressBar setProgress arg1                        IntentFilter progressfilter   new IntentFilter Events UPDATE DOWNLOADING PROGRESS       registerReceiver broadcastReceiver progressfilter     For sending more data  you can modify method sendBroadcastMessage     Remember  you must register broadcasts in onResume    amp  unregister in onStop   methods   UPDATE  Please don t use my type of communication between Activity  amp  Service  This is the wrong way  For a better experience please use special libs  such us   1   EventBus from greenrobot  2  Otto from Square Inc  P S  I m only using EventBus from greenrobot in my projects

User · Answer

Everything is fine Good example of activity service communication using Messenger   One comment   the method MyService isRunning   is not required   bindService   can be done any number of times  no harm in that   If MyService is running in a different process then the static function MyService isRunning   will always return false  So there is no need of this function

User · Answer

Message msg   Message obtain null  2  0  0                       Bundle bundle   new Bundle                        bundle putString  url   url                       bundle putString  names   names                       bundle putString  captions  captions                        msg setData bundle     So you send it to the service  Afterward receive

User · Answer

Great tutorial  fantastic presentation  Neat  simple  short and very explanatory  Although  notification setLatestEventInfo this  getText R string service label   text  contentIntent   method is no more  As trante stated here  good approach would be   private static final int NOTIFICATION ID   45349   private void showNotification         NotificationCompat Builder builder               new NotificationCompat Builder this                       setSmallIcon R mipmap ic launcher                       setContentTitle  My Notification Title                        setContentText  Something interesting happened         Intent targetIntent   new Intent this  MainActivity class       PendingIntent contentIntent   PendingIntent getActivity this  0  targetIntent  PendingIntent FLAG UPDATE CURRENT       builder setContentIntent contentIntent        nManager    NotificationManager  getSystemService Context NOTIFICATION SERVICE        nManager notify NOTIFICATION ID  builder build         Override public void onDestroy         super onDestroy        if   timer    null    timer cancel          counter 0       nManager cancel NOTIFICATION ID      Cancel the persistent notification      Log i  PlaybackService    Service Stopped          isRunning   false      Checked myself  everything works like a charm  activity and service names may differ from original

User · Answer

I have seen all answers  I want tell most robust way now a day  That will make you communicate between Activity - Service - Dialog - Fragments  Everything    EventBus  This lib which i am using in my projects has great features related to messaging   EventBus in 3 steps   Define events   public static class MessageEvent      Additional fields if needed      Prepare subscribers    Declare and annotate your subscribing method  optionally specify a thread mode      Subscribe threadMode   ThreadMode MAIN   public void onMessageEvent MessageEvent event      Do something        Register and unregister your subscriber  For example on Android  activities and fragments should usually register according to their life cycle    Override public void onStart         super onStart        EventBus getDefault   register this       Override public void onStop         super onStop        EventBus getDefault   unregister this        Post events   EventBus getDefault   post new MessageEvent       Just add this dependency in your app level gradle   compile  org greenrobot eventbus 3 1 1

User · Answer

Look at the LocalService example   Your Service returns an instance of itself to consumers who call onBind  Then you can directly interact with the service  e g  registering your own listener interface with the service  so that you can get callbacks

User · Answer

Seems to me you could ve saved some memory by declaring your activity with  implements Handler Callback

User · Answer

This is how I implemeted Activity- Service Communication  on my Activity i had   private static class MyResultReciever extends ResultReceiver                   Create a new ResultReceive to receive results   Your          link  onReceiveResult  method will be called from the thread running         lt var gt handler lt  var gt  if given  or from an arbitrary thread if null                 param handler              public MyResultReciever Handler handler             super handler                 Override      protected void onReceiveResult int resultCode  Bundle resultData             if  resultCode    100                   dostuff                     And then I used this to start my Service  protected void onCreate Bundle savedInstanceState    MyResultReciever resultReciever   new MyResultReciever handler           service   new Intent this  MyService class           service putExtra  receiver   resultReciever           startService service       In my Service i had  public int onStartCommand Intent intent  int flags  int startId        if  intent    null          resultReceiver   intent getParcelableExtra  receiver        return Service START STICKY      Hope this Helps

[android] Example: Communication between Activity and Service using Messaging

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