Develop Reference

How to Send BroadCast from one app to another app

I have App A and App B. In App A I want to send broadcast to App B.
This is the code for App A:
final Intent intent = new Intent();
intent.setAction("com.pkg.perform.Ruby");
intent.putExtra("KeyName", "code1id");
intent.setComponent(new ComponentName("com.pkg.AppB", "com.pkg.AppB.MainActivity"));
sendBroadcast(intent);
And in App B - In MainActivity, I have MyBroadCastReceiver Class.
public class MainActivity extends Activity {
private MyBroadcastReceiver MyReceiver;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Receive broadcast from External App
IntentFilter intentFilter = new IntentFilter("com.pkg.perform.Ruby");
MyReceiver = new MyBroadcastReceiver();
if(intentFilter != null)
{
registerReceiver(MyReceiver, intentFilter);
}
}
public class MyBroadcastReceiver extends BroadcastReceiver
{
#Override
public void onReceive(Context context, Intent intent) {
Toast.makeText(MainActivity.this, "Data Received from External App", Toast.LENGTH_SHORT).show();
}
}
#Override
protected void onDestroy() {
super.onDestroy();
if(MyReceiver != null)
unregisterReceiver(MyReceiver);
}
}
I am getting the error - Receiver is not registered.

First thing first declare the receiver in app B in the manifest file like this:
<receiver android:name=".MyBroadcastReceiver"
android:enabled="true"
android:exported="true">
<intent-filter>
<action android:name="com.pkg.perform.Ruby" />
</intent-filter>
</receiver>
when sending the broadcast add FLAG_INCLUDE_STOPPED_PACKAGES flag to the intent [src] because when you broadcast from app A to app B , app B might not be running, this flag insures that the broadcast reachs out even apps not running:
FLAG_INCLUDE_STOPPED_PACKAGES flag is added to the intent before it
is sent to indicate that the intent is to be allowed to start a
component of a stopped application.
intent.addFlags(Intent.FLAG_INCLUDE_STOPPED_PACKAGES);
In your case it will be like this:
final Intent intent=new Intent();
intent.setAction("com.pkg.perform.Ruby");
intent.putExtra("KeyName","code1id");
intent.addFlags(Intent.FLAG_INCLUDE_STOPPED_PACKAGES);
intent.setComponent(
new ComponentName("com.pkg.AppB","com.pkg.AppB.MyBroadcastReceiver"));
sendBroadcast(intent);

In App A: Send the broadcast here.
final Intent i= new Intent();
i.putExtra("data", "Some data");
i.setAction("com.pkg.perform.Ruby");
i.addFlags(Intent.FLAG_INCLUDE_STOPPED_PACKAGES);
getApplicationContext().sendBroadcast(i);
In App B manifest
<receiver android:name=".MyBroadcastReceiver"
android:enabled="true"
android:exported="true">
<intent-filter>
<action android:name="com.pkg.perform.Ruby" />
</intent-filter>
</receiver>
In App B MainActivity: register the receiver oncreate(), and unregister onDestroy()
public class MainActivity extends AppCompatActivity
{
private MyBroadcastReceiver MyReceiver;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
MyReceiver = new MyBroadcastReceiver();
IntentFilter intentFilter = new IntentFilter("com.pkg.perform.Ruby");
if(intentFilter != null)
{
registerReceiver(MyReceiver, intentFilter);
}
}
#Override
protected void onDestroy()
{
super.onDestroy();
if(MyReceiver != null)
unregisterReceiver(MyReceiver);
}
}
In App B BroadcastReceiver
public class MyBroadcastReceiver extends BroadcastReceiver
{
#Override
public void onReceive(Context context, Intent intent)
{
String data = intent.getStringExtra("data");
Log.i("BR" ,"Data received: " + data);
}
}

There may be two cases :
Your appB is not running, hence the activity is not instantiated, and so the receiver is not registered.
Your activity is destroyed, means that you have unregistered your receiver that you registered via registerReceiver() in onCreate()
Solution :
Register your broadcast receiver in manifest.
Inside manifest of appB :
<receiver android:name=".MyBroadcastReceiver">
<intent-filter>
<action android:name="com.pkg.perform.Ruby" />
</intent-filter>
</receiver>
And comment out the line in appA
intent.setComponent(new ComponentName("com.pkg.AppB","com.pkg.AppB.MainActivity"));
Write the logic in MyBroadcastReceiver to display relevant data/launch new activity

MyReceiver is class not object. Create
myReceiver = new MyReceiver();
and put...........
registerReceiver(myReceiver,intentFilter);

If this helps some one and it works for me
In App A in activity or in a content provider-
Intent intent = new Intent("Updated");
intent.addFlags(Intent.FLAG_INCLUDE_STOPPED_PACKAGES);
intent.setComponent (new
ComponentName "com.exam.appA",
"com.exam.appA.DbaseChanged"));
getContext().sendBroadcast(intent);
In App B in the manifest
<receiver
android:name=".DbaseChanged"
android:enabled="true"
android:exported="true">
<intent-filter>
<action android:name="Updated" />
</intent-filter>
</receiver>
In App B Broadcast receiver class-
public class DbaseChanged extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent
intent) {
String act = intent.getAction();
if(act != null && act.equals("Updated") )
{
Toast.makeText(context, act ,
Toast.LENGTH_SHORT).show();
}
}
}

I needed to call setPackage("package_name") to ensure explicitness when I registered the broadcast receiver in the Manifest. I was then able to receive the data even if the app was closed completely.
// sending app sends broadcast
Intent intent = new Intent(ACTION_RECOMMEND);
intent.putExtra(LISTEN_RECOMMENDATION, "Triggered - Jhene Aiko");
intent.putExtra(WATCH_RECOMMENDATION, "Goblin - Kim Go-eun");
intent.setPackage("com.example.package.receiverapp");
sendBroadcast(intent);
//receiving app manifest registers receiver
<receiver
android:name=".ManifestRegisteredBroadcastReceiver"
android:exported="true">
<intent-filter>
<action android:name="com.random.action.RECOMMEND" />
</intent-filter>
</receiver>
I didn't need to add intent.setPackage(package_name) when registering the receiver via an activity, but this also meant that I couldn't get the data if the activity was destroyed (app closed, app in background for long period)

How can I start receiver class from an Activity in android?

I have an activtiy and a receiver.class with broadcastreceiver. I would like to start receiver from mainactivity but I could not do this with my solution.
Here is may way
Intent iinent= new Intent(MainActivity.this,MyReceiver.class);
startActivity(iinent);
When I try this app says me Unfortunately app has stopped'' and my logcat says this intent' line s incorrect.
Is there another way to do this?

For Sending Broadcast Receiver Broadcast Receiver must be registered
in Manifest
<receiver android:name="TestReceiver">
<intent-filter>
<action android:name="ACTION_NAME"/>
</intent-filter>
</receiver>
In Activity
IntentFilter filter = new IntentFilter();
filter.addAction("ACTION_NAME");
BroadcastReceiver receiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
//do something based on the intent's action
}
}
registerReceiver(receiver, filter);
SendBroadcast
Intent intnet = new Intent("ACTION_NAME");
sendBroadcast(intnet);

Register a Local BroadcastReceiver in AndroidManifest.xml?

Is there anyway to register a BroadcastReceiver in AndroidManifest.xml and receives broadcast that is send by a LocalBroadcastManager?
Currently I must call
registerReceiver(BroadcastReceiver receiver, IntentFilter filter)
to register a Receiver, declare in AndroidManifest.xml won't work. But this means I must know exactly the receiver's package name and class name, not just the intent filter. Is it possible to declare the receiver in the manifest file?
following is my current code.
AndroidManifest.xml:
...
<receiver
android:name="com.example.test.MessageReceiver"
android:enabled="true" >
<intent-filter>
<action android:name="com.m2x.test.intent.MESSAGE_RECEIVED" />
</intent-filter>
</receiver>
...
MainActivity.java:
Intent intent = new Intent();
intent.setAction("com.m2x.test.intent.MESSAGE_RECEIVED");
LocalBroadcastManager manager = LocalBroadcastManager.getInstance(mContext.get());
manager.sendBroadcast(intent);
MessageReceiver.java
public class MessageReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals("com.m2x.test.intent.MESSAGE_RECEIVED")) {
Toast.makeText(context, "user message received", Toast.LENGTH_SHORT).show();
}
}
}

No, you can't.
The local BroadcastReceiver isn't a real BroadcastReceiver, basically its a list of callbacks functions.
You can check the source code of LocalBroadcastManager.java.

Android Register BroadcastReceiver to run continously

I want to implement a minimal screen activity logger app. So, the application should run on the background (no user interaction) and it will log the screen on and off activities. I have started these codes, but it seems that I need to register my ScreenBroadcastReceiver broadcastreceiver. If I do it with the below code in main activity, it works. However, I do not want to register it in main because the user cannot launch the activity every time. So, where should i register my BroadcastReceiver so that the application works without user interaction?
oncreate in main activity
//I need to find another place to put these code, Where ???
//IntentFilter filter = new IntentFilter(Intent.ACTION_SCREEN_ON);
//filter.addAction(Intent.ACTION_SCREEN_OFF);
//BroadcastReceiver screenOnReceiver = new ScreenBroadcastReceiver();
//registerReceiver(screenOnReceiver, filter);
This is ScreenBroadcastReceiver, it will be triggered when the screen is on.
public class ScreenBroadcastReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(Intent.ACTION_SCREEN_ON)) {
Log.w("OnReceive", "SCREEN IS ON");
}
}
}
This is the BootReceiver to run the program on the background itself.
public class BootReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
Intent service = new Intent(context, ScreenListenerService.class);
context.startService(service);
//IntentFilter filter = new IntentFilter(Intent.ACTION_SCREEN_ON);
//filter.addAction(Intent.ACTION_SCREEN_OFF);
//BroadcastReceiver screenOnReceiver = new ScreenBroadcastReceiver();
//context.registerReceiver(screenOnReceiver, filter);
}
}
This is the manifest:
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>
<service android:name=".ScreenListenerService"></service>
<receiver android:name=".BootReceiver">
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED" />
</intent-filter>
</receiver>
Update:
I added a service, but it does not work. Did i forget to add something? or what ?
public class ScreenListenerService extends Service {
public void OnCreate(){
IntentFilter filter = new IntentFilter(Intent.ACTION_SCREEN_ON);
filter.addAction(Intent.ACTION_SCREEN_OFF);
BroadcastReceiver screenOnReceiver = new ScreenBroadcastReceiver();
registerReceiver(screenOnReceiver, filter);
}
#Override
public IBinder onBind(Intent intent) {
// TODO Auto-generated method stub
return null;
}
}

use Service for your purpose and do the same as you did in the activity.

ACTION_SCREEN_ON and ACTION_SCREEN_OFF not working?

I'm trying to turn WiFi off when the screen is OFF (locked), and turn it on again when screen is ON (unlocked).
I made a BroadcastReceiver; put in manifest this code:
<receiver android:name="MyIntentReceiver">
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED" />
<action android:name="android.intent.action.SCREEN_OFF" />
<action android:name="android.intent.action.SCREEN_ON" />
<action android:name="android.intent.action.USER_PRESENT" />
<category android:name="android.intent.category.HOME" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</receiver>
and this is the class MyIntentReceiver:
package org.androidpeople.boot;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
public class MyIntentReceiver extends BroadcastReceiver {
// Called when boot completes
public static boolean startup;
#Override
public void onReceive(Context context, Intent intent) {
// Set what activity should launch after boot completes
System.out.println("Intent Action: " + intent.getAction());
if (intent.getAction().equals(Intent.ACTION_SCREEN_OFF)) {
System.out.println("locked : ACTION_SCREEN_OFF");
} else if (intent.getAction().equals(Intent.ACTION_SCREEN_ON)) {
System.out.println("not locked : ACTION_SCREEN_ON ");
} else if (intent.getAction().equals(Intent.ACTION_SCREEN_ON)) {
System.out.println("User Unlocking it ");
}
else if (intent.getAction().equals(Intent.ACTION_BOOT_COMPLETED)) {
// this to indicate that program is running
// automaticlly not manually by user
startup = true;
System.out.println("Automatic BOOT at StartUp");
Intent startupBootIntent = new Intent(context, LaunchActivity.class);
startupBootIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(startupBootIntent);
}
}
}
And the result is - both ACTION_SCREEN_ON
and ACTION_SCREEN_OFF never fired!
USER_PRESENT and BOOT_COMPLETED worked fine but the other did not. I'm using an emulator, not a real device - can this cause the problem?
Any help?
I need to catch the screen on and off in order to enable/disable WiFi
to save battery.
Thanks in advance

To capture the SCREEN_OFF and SCREEN_ON actions (and maybe others) you have to configure the BroadcastReceiver by code, not through the manifest.
IntentFilter intentFilter = new IntentFilter(Intent.ACTION_SCREEN_ON);
intentFilter.addAction(Intent.ACTION_SCREEN_OFF);
BroadcastReceiver mReceiver = new ScreenStateBroadcastReceiver();
registerReceiver(mReceiver, intentFilter);
It's tested and works right.

You cannot catch those intents through XML (I forget why). However, you could use a Service that registers a BroadcastReceiver member in its onStartCommand() and unregisters it in its onDestroy(). This would require the service to be running in the background, constantly or as long as you need it to, so be sure to explore alternative routes.
You could define the BroadcastReceiver in your Service class like so:
private final class ScreenReceiver extends BroadcastReceiver {
#Override
public void onReceive(final Context context, final Intent intent) {
if (intent.getAction().equals(Intent.ACTION_SCREEN_OFF)) {
//stuff
} else if (intent.getAction().equals(Intent.ACTION_SCREEN_ON)) {
//other stuff
}
}
}
For a slightly complicated example, but one that shows how the BroadcastReceiver and Service interact see CheckForScreenBugAccelerometerService from my app, ElectricSleep.