Android BroadcastReceiver within Activity

Question

I m just trying this little sample project  all it does  Activity one has a Button that sends a Broadcast  Activity two displays a toast when received  Below is the code  the Broadcast is never received  What do I do wrong   Sending the Broadcast  public class SendBroadcast extends Activity        public static String BROADCAST ACTION    com unitedcoders android broadcasttest SHOWTOAST            Called when the activity is first created          Override     public void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout main              public void sendBroadcast View v           Intent broadcast   new Intent            broadcast setAction BROADCAST ACTION           sendBroadcast broadcast             Receiving it  public class ToastDisplay extends Activity        private BroadcastReceiver receiver   new BroadcastReceiver              Override         public void onReceive Context context  Intent intent                Toast makeText getApplicationContext     received   Toast LENGTH SHORT                          Override     protected void onResume             IntentFilter filter   new IntentFilter            filter addAction SendBroadcast BROADCAST ACTION           registerReceiver receiver  filter           super onResume                Override     protected void onPause             unregisterReceiver receiver           super onPause              Manifest   lt application android icon   drawable icon  android label   string app name  gt       lt activity android name   SendBroadcast  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 activity android name   ToastDisplay  gt           lt intent-filter gt               lt action android name  com unitedcoders android broadcasttest SHOWTOAST  gt  lt  action gt           lt  intent-filter gt       lt  activity gt   lt  application gt

User · Answer

I think your problem is that you send the broadcast before the other activity start   so the other activity will not receive anything     The best practice to test your code is to sendbroadcast from thread or from a service so the activity is opened and its registered the receiver and the background process sends a message  start the ToastDisplay activity from the sender activity   I didn t test that but it may work probably

User · Answer

You forget to write  show   at the end  which is used to show the toast message      Toast makeText getApplicationContext     received   Toast LENGTH SHORT  show      It is a common mistake that programmer does  but i am sure after this you won t repeat the mistake again     D

User · Answer

Your also have to register the receiver in onCreate    like this    IntentFilter filter   new IntentFilter    filter addAction  csinald meg    registerReceiver receiver  filter

User · Answer

What do I do wrong    The source code of ToastDisplay is OK  mine is similar and works   but it will only receive something  if it is currently in foreground  you register receiver in onResume   But it can not receive anything if a different activity  in this case SendBroadcast activity  is shown   Instead you probably want to startActivity ToastDisplay from the first activity   BroadcastReceiver and Activity make sense in a different use case  In my application I need to receive notifications from a background GPS tracking service and show them in the activity  if the activity is in the foreground    There is no need to register the receiver in the manifest  It would be even harmful in my use case - my receiver manipulates the UI of the activity and the UI would not be available during onReceive if the activity is not currently shown  Instead I register and unregister the receiver for activity in onResume and onPause as described in  BroadcastReceiver documentation      You can either dynamically register an instance of this class with Context registerReceiver   or statically publish an implementation through the  tag in your AndroidManifest xml

User · Answer

You need to define the receiver as a class in the manifest and it will receive the intent    lt application           lt receiver android name   ToastReceiver  gt       lt intent-filter gt         lt action android name  com unitedcoders android broadcasttest SHOWTOAST   gt       lt  intent-filter gt     lt  receiver gt   lt  application gt    And you don t need to create the class manually inside ToastDisplay   In the code you provided  you must be inside ToastDisplay activity to actually receive the Intent

User · Answer

Extends the ToastDisplay class with BroadcastReceiver and register the receiver in the manifest file and dont register your broadcast receiver in onResume       lt application           lt receiver android name   ToastDisplay  gt       lt intent-filter gt         lt action android name  com unitedcoders android broadcasttest SHOWTOAST   gt       lt  intent-filter gt     lt  receiver gt   lt  application gt    if you want to register in activity then register in the onCreate   method e g   onCreate         sentSmsBroadcastCome   new BroadcastReceiver               Override         public void onReceive Context context  Intent intent                Toast makeText context   SMS SENT     Toast LENGTH SHORT  show                         IntentFilter filterSend   new IntentFilter        filterSend addAction  m sent        registerReceiver sentSmsBroadcastCome  filterSend

User · Answer

Toast makeText getApplicationContext     received   Toast LENGTH SHORT     makes the toast  but doesnt show it    You have to do Toast makeText getApplicationContext     received   Toast LENGTH SHORT  show

[android] Android BroadcastReceiver within Activity

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