I am new to android platform.please help me out how the Broadcast Receiver and Intent Filter behaves in android.please explain in simple line or with example.thanks in advance...
A broadcast receiver is a class in your Android project which is responsible to receive all intents, which are sent by other activities by using android.content.ContextWreapper.sendBroadcast(Intent intent)
In the manifest file of you receicving activity, you have to declare which is your broadcast receiver class, for example:
<receiver android:name="xyz.games.pacman.network.MessageListener">
<intent-filter>
<action android:name="xyz.games.pacman.controller.BROADCAST" />
</intent-filter>
</receiver>
As you can see, you also define the intent filter here, that is, which intents should be received by the broadcas receiver.
Then you have to define a class which extends BroadcastReceiver. This is the class you defined in the manifest file:
public class MessageListener extends BroadcastReceiver {
/* (non-Javadoc)
* #see android.content.BroadcastReceiver#onReceive(android.content.Context, android.content.Intent)
*/
#Override
public void onReceive(Context context, Intent intent) {
...
}
Here, all intents which are passed through the filter are received and you can access them using the parameter passed in the method call.
A BroadcastReceiver can be registered in two ways: dynamic or static. Static is nothing but declaring the action through an intent-filter in AndroidManifest.xml to register a new BroadcastReceiver class. Dynamic is registering the receiver from within another class. An intent-filter determines which action should be received.
To create a BroadcastReceiver, you have to extend the BroadcastReceiver class and override onReceive(Context,Intent) method. Here you can check the incoming intent with Intent.getAction() and execute code accordingly.
As a new class, static would be
public class Reciever1 extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
String str = intent.getAction();
if(str.equalsIgnoreCase("HELLO1")) {
Log.d("Abrar", "reciever....");
new Thread() {
public void run() {
Log.d("Abrar", "reciever....");
System.out.println("Abrar");
}
}.start();
}
or, if placed inside an existing class, it is called dynamically with
intentFilter = new IntentFilter();
intentFilter.addAction("HELLO1");
//---register the receiver---
registerReceiver(new Reciever1(), intentFilter);
BroadcastReceiver : 'Gateway' with which your app tells to Android OS that, your app is interested in receiving information.
Intent-Filter : Works with BroadcastReceiver and tells the 'What' information it is interested to receive in. For example, your app wants to receive information on Battery level.
Related
I have an IntentService defined as below:
<service android:name=".service.AppService" android:process=":app_process" android:icon="#mipmap/ic_launcher" />
I have a WakefulBroadcastReceiver that receives some data and I would like to call my already running service above. The service above is always running, even if it is killed, it restarts. How can I pass messages to that?
I read the following:
http://www.mysamplecode.com/2011/10/android-intentservice-example-using.html
http://www.truiton.com/2014/09/android-service-broadcastreceiver-example/
http://developer.android.com/guide/components/services.html
I tried to do a startService, PendingIntent among other things and nothing seems to work.
First of all, remember that an IntentService works in a different worker thread, there for it's not possible to have intercommunication with the Activity that invoked it. That's why mostly we use them for synchronization on background where feedback to the user is not needed. However, if you want to pass some information to the Activity, you have to use a BroadcastReceiver as you said, and from there create the Intent that will send "data" to the Activity.
Going back to your question, you have to add the service and the receiver in your AndroidManifest.xml inside the <application> tag
<service android:name=".AppService"
android:enabled="true"/>
<receiver android:name=".WakefulBroadcastReceiver" >
</receiver>
Then in your Activity launch the service like this (whenever you need it, in the onCreate, or in a button listener)
IntentFilter filter = new IntentFilter(WakefulBroadcastReceiver.ACTION_RESP);
filter.addCategory(Intent.CATEGORY_DEFAULT);
WakefulBroadcastReceiver broadcastReceiver = new WakefulBroadcastReceiver();
registerReceiver(broadcastReceiver, filter);
In your BroadcastReceiver you override the onReceive() method like this:
#Override
public void onReceive(Context context, Intent intent) {
// HERE IS WHERE YOU RECEIVE THE INFORMATION FROM THE INTENTSERVICE, FROM HERE YOU CAN START AN ACTIVITY OR WHATEVER YOU AIM
Toast.makeText(context, "IntentService Broadcasting", Toast.LENGTH_SHORT).show();
}
Also in the same BroadcastReceiver add this variable that identifies the intentfilter:
public static final String ACTION_RESP = "MY_FILTER_NAME"
In your IntentService class you have to override the onHandleIntent() method like this:
#Override
protected void onHandleIntent(Intent intent) {
String msg = intent.getStringExtra("MSG");
Intent broadcast = new Intent();
broadcast.setAction(WakefulBroadcastReceiver.ACTION_RESP);
broadcast.addCategory(Intent.CATEGORY_DEFAULT);
broadcast.putExtra("MSG", resultTxt);
// HERE IS WHERE YOU SEND THE INFORMATION YOU LOADED TO THE APP
sendBroadcast(broadcast);
}
I have a demo project in my GitHub account here, where I use bound and unbound services and IntentServices:
https://github.com/isaacurbina/PermissionsAndServices
I hope it helps.
Kind regards!
You can write this in your class that extends WakefulBroadcastReceiver :
#Override
public void onReceive(Context context, Intent intent) {
Intent gcmIntent = new Intent(context, MessageService.class);
gcmIntent.putExtras(intent.getExtras());
startWakefulService(context, gcmIntent);
setResultCode(Activity.RESULT_OK);
}
And write this in your class that extend IntentService :
#Override
protected void onHandleIntent(Intent intent) {
Bundle bundle = intent.getExtras();
//do sth with that data
MessageReceiver.completeWakefulIntent(intent);
}
the title says all, I need to change the variable of my service from a activity in my other app , what to finalize the service or not, this is possible?
I found the Message object , but I do not quite understand
The simplest solution would be to implement a BroadcastReceiver. Your Service listens for the Broadcast and the other App sends the Broadcast.
Example Reciever:
public class MyReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
// Get bundle from intent and use it to set your Variable in your Service
}
}
Example Broadcaster (courtesy of Vogella):
Intent intent = new Intent();
intent.setAction("de.vogella.android.mybroadcast");
sendBroadcast(intent);
Hi i am trying to understand Broadcast Receiver , i went through many sample codes , but still have some doubts. I wanted to know when we have to extend the Broadcast Receiver class and when should we use registerReceiver() method and when should we create object for BroadcastReceiver. In some programs i came across registerReceiver methods being used but without extending the Broadcast Receiver class. I also wanted to know how the onReceive method gets called.
Which approach should be used when?
here is the registerReceiver method:
registerReceiver(new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
switch (getResultCode()) {
........
}
}
}, new IntentFilter(SENT));
Object being created for BroadcastReceiver:
private BroadcastReceiver intentReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
.................
}
};
Android has intent action for broadcast receiver. BroadCast receiver will be trigger when it listen any action which registered within it.
Now we will take one example :
That we need to listen the action of "whenever any bluetooth device connect to our device". For that android has it fix action android.bluetooth.BluetoothDevice.ACTION_ACL_CONNECTED
So you can get it via manifest & registration also
BY Manifest Registration:
Put this in your manifest
<receiver android:name="MyBTReceiver">
<intent-filter>
<action android:name="android.bluetooth.BluetoothDevice.ACTION_ACL_CONNECTED" />
</intent-filter>
</receiver>
Create MyBTReceiver.class
public class MyBTReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
if(intent.getAction().equals("android.bluetooth.BluetoothDevice.ACTION_ACL_CONNECTED")){
Log.d(TAG,"Bluetooth connect");
}
}
}
That was the simplest broadcast Receiver.
Now,
if you are only interested in receiving a broadcast while you are running, it is better to use registerReceiver(). You can also register it within your existing class file. you also need to unregister it onDestroy().
here, you dont need any broadcast registration in manifest except activity registration
For example
public class MainActivity extends Activity {
IntentFilter filter1;
#Override
public void onCreate() {
filter1 = new IntentFilter("android.bluetooth.BluetoothDevice.ACTION_ACL_CONNECTED");
registerReceiver(myReceiver, filter1);
}
//The BroadcastReceiver that listens for bluetooth broadcasts
private final BroadcastReceiver myReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
if(intent.getAction().equalsIgnoreCase("android.bluetooth.BluetoothDevice.ACTION_ACL_CONNECTED")) {
Log.d(TAG,"Bluetooth connect");
}
}
};
#Override
public void onDestroy() {
unregisterReceiver(myReceiver);
}
}
In both cases BroadcastReceiver will be extended. In your second example you create so called anonymous class. New class has no specific name, that is why it's called so. Anyway this new class extends BroadcastReceiver and overrides onReceive() method.
Now back to your question. There are two kinds of receivers - statically and dynamically defined ones.
If you declare your receiver in AndroidManifest file, then it is statically defined. In this case you need to refer to a class implementing BroadcastReceiver by name. As you can see, you cannot use an anonymous class, because the last has no name. You have to explicitly implement a receiver. It's worth to mention, that in this case you do not use registerReceiver() method. Android does it for you automatically.
If you declare receivers dynamically (for instance in activity's onResume() method), then you can use anonymous class for that. To register a receiver you call registerReceiver() method. You can also use a named class too. Both options are valid in this case.
Hope this explains the difference.
In both case you are creating object.But in first case there is not any reference for
the receiver object so it can not be unregistered later but second one has so it can be
unregistered after registering object using below methods:
registerReceiver(intentReceiver );
unregisterReceiver(intentReceiver );
i am new to Android and trying to understand the communication between apps.
I am trying to write 3 little apps which can communicate with each other. If you want to sent a message to everybody you just use an implicit broadcast.
implicit Intent intent.setAction("com.example.myChatMessage")
if you want to adress only 1 specifc receiver i did it with
explicite Intentintent.setComponent("com.example.test.android.broadcastreceiver.b",
"com.example.test.android.broadcastreceiver.b.myBroadcastReceiver")
this works, when the broadcast receiver is a seperate class and defined in the AndroidManifest.xml.
My Question: Is it possible to explicit adress a dynamicall registered broadcast receiver?
package com.example.test.android.broadcastreceiver.b;
public class MainActivity extends Activity {
private final IntentFilter intentfilter = new IntentFilter("com.example.myChatMessage");
private myBroadcastReceiver broadcastreceiver;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
broadcastreceiver = new myBroadcastReceiver();
registerReceiver(broadcastreceiver, intentfilter);
}
public static class myBroadcastReceiver extends BroadcastReceiver{
#Override
public void onReceive(Context context, Intent intent) {
String message = intent.getStringExtra("message");
Log.d("message", "B received: "+message);
}
}
}
It receives all implicit broadcasts but no explicit one - i don't know hot to adress it. Can you help me?
It does not appear possible to send an explicit intent to a dynamically registered broadcast receiver. Registering the receiver in AndroidManifest.xml is the only way.
If you dynamically register a BroadcastReceiver – by calling Context.registerReceiver() – you supply a BroadcastReceiver instance ... If you try to send an Intent to the receiver by naming the class of the BroadcastReceiver, it will never get delivered .. The Android system will not match the Intent you declared to the class of the BroadcastReceiver instance you registered.
Source: http://onemikro2nd.blogspot.com/2013/09/darker-corners-of-android.html
I am writing an alarm code and using a broadcast receiver. I am able to receive the broadcast receiver. but now I want to come back to the calling activity and update the UI of my activity. I am not able to this.
I used the following code in my activity but it is never executing that code.
private BroadcastReceiver myBroadcastReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
Toast.makeText(context, "I am back!!", Toast.LENGTH_LONG).show();
}
};
#Override
protected void onPause()
{
super.onPause();
unregisterReceiver(myBroadcastReceiver);
}
#Override
protected void onResume()
{
super.onResume();
IntentFilter intentFilter = new IntentFilter("com.test.Main");
registerReceiver(myBroadcastReceiver, intentFilter);
}
in the manifest file I have included the following, here gotAlarm is the broadcast receiver file
<receiver android:name=".gotAlarm"
android:enabled="true">
</receiver>
gotAlarm file is one which gets called from the pending intent of the alarm set
public class gotAlarm extends BroadcastReceiver {
public void onReceive(Context context, Intent intent){
Toast.makeText(context, "Wake Up!!", Toast.LENGTH_LONG).show();
}
}
May be I am missing something very basic.
please help.
Two things:
If you dynamically register the receiver via Context.registerReceiver() then you won't receive broadcasts when Activity is paused (or stopped or not-running). If you need to receive broadcasts even when Activity is paused then create a top-level BroadcastReceiver class (as opposed to your inner class) and use <receiver> to register it.
BroadcastReceiver lifecycle docs state that BroadcastReceiver object is alive only during processing of onReceive(). You can not do any async tasks like showing dialogs, etc.. In your case (Activities might not be running and you receive a broadcast) you should use NotificationManager to notify user something happened.
I have dropped this way and I am starting a new activity on receiving broadcast. And I am sending information data from calling activity to broadcast and from broadcast to next activity. This has served the purpose.
Did you register your BroadcastReceiver (you can do this in the 'onResume'-method of your Activity)? Also, you should unregister your BroadcastReceiver in the 'onPause'-method.