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Can a Broadcast Receiver send information to an Activity only if it is active without starting a new Activity?

I have a broadcast receiver that gets triggered on geofencing events and either "clocks in" or "clocks out" with the server. If my application's "Attendance" activity is already open I would like it to display the clocking status change but I don't want the Broadcast Receiver to start the activity if it's not open - in other words display the change "live" while the activity is open only.
The way I imagine doing this is with the Broadcast Receiver sending an Intent to the activity but name "startActivity()" doesn't sound encouraging unless there are any special flags I can pass to prevent starting an Activity that isn't already open - I can't seem to find any.
The other option would be to constantly poll the value while the activity is open but it doesn't seem optimal so I would only use it if there wasn't another way and I can't think of a reason why it couldn't be possible with Intents.

There are several different ways to accomplish the same task. One is registering a listener like the following example:
MainActivity
public class MainActivity extends AppCompatActivity
{
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Receiver.setOnReceiveListener(new Receiver.OnReceiveListener() {
public void onReceive(Context Context, Intent intent)
{
//Do something.
}
});
}
#Override
protected void onDestroy()
{
super.onDestroy();
Receiver.setOnReceiveListener(null);
}
}
Receiver
public class Receiver extends BroadcastReceiver
{
private static OnReceiveListener static_listener;
public static abstract interface OnReceiveListener
{
public void onReceive(Context context, Intent intent);
}
public static void setOnReceiveListener(OnReceiveListener listener)
{
static_listener = listener;
}
#Override
public final void onReceive(Context context, Intent intent)
{
if(static_listener != null) {
static_listener.onReceive(context, intent);
}
}
}

Just have your BroadcastReceiver send a broadcast Intent. Your Activity should register a listener from this broadcast Intent and if it gets triggered, it can update the UI.
Here's an example:
Declare a private member variable in your Activity:
private BroadcastReceiver receiver;
In Activity.onCreate(), register the BroadcastReceiver:
IntentFilter filter = new IntentFilter();
filter.addAction("my.package.name.CLOCK_STATUS_CHANGE");
receiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
// Here you can update the UI ...
}
};
registerReceiver(receiver, filter);
And in onDestroy() you can unregister it (probably not necessary, but cleaner):
if (receiver != null) {
unregisterReceiver(receiver);
receiver = null;
}
In your BroadcastReceiver that detects the geofencing event, you should create and send a broadcast Intent:
Intent broadcastIntent = new Intent("my.package.name.CLOCK_STATUS_CHANGE");
sendBroadcast(broadcastIntent);

How to pass data from BroadcastReceiver to Activity without in onCreate()

I have a serious issue about passing data from BroadcastReceiver to an Activity. Let see my issue carefully. I have a class PhoneStateReceiver extends BroadcastReceiver that used to received an incoming phone.
public class PhoneStateReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
try {
System.out.println("Receiver start");
String state = intent.getStringExtra(TelephonyManager.EXTRA_STATE);
String incomingNumber = intent.getStringExtra(TelephonyManager.EXTRA_INCOMING_NUMBER);
if(state.equals(TelephonyManager.EXTRA_STATE_RINGING)){
}
}
catch (Exception e){
e.printStackTrace();
}
}
}
The incoming phone will be sent to an Activity, called ReceiverActivity. The ReceiverActivity receives the incoming phone and sends it to a server via a socket connection. The socket connection is initialized in the onCreate function. I googled and found server way to pass the data from BroadcastReceiver to an Activity. The common way is that send data via putExtra function and call startActivity. However, the way will call the onCreate again and then connect the socket, draw the UI again. Thus, it is not helpful in my case.
In my goal, If the phone receives an incoming call, it will send the incoming call to the ReceiverActivity. The ReceiverActivity receives the message and calls the send function. Which is the best way to do it? Thank you
The common way to pass data from a BroadcastReceiver to a ReceiverActivity that I used as follows
In PhoneStateReceiver class :
Intent intent_phonenum = new Intent(context, ReceiverActivity.class);
intent_phonenum.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent_phonenum.putExtra("phone_num", incomingNumber);
context.startActivity(intent_phonenum);
In ReceiverActivity class :
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
connect_socket();
Intent intent = getIntent();
phone_num = intent.getStringExtra("phone_num");
send(phone_num);
}

Simple without any third party libs.
Make sure BroadcastReceiver must be registered and also unregistered on OnPause().
You have to do two thing
Register a receiver in you activity like below.
public class MainActivity extends Activity {
Context context;
BroadcastReceiver updateUIReciver;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
context = this;
IntentFilter filter = new IntentFilter();
filter.addAction("service.to.activity.transfer");
updateUIReciver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
//UI update here
if (intent != null)
Toast.makeText(context, intent.getStringExtra("number").toString(), Toast.LENGTH_LONG).show();
}
};
registerReceiver(updateUIReciver, filter);
}
}
Now in you service
public class PhoneStateReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
try {
System.out.println("Receiver start");
String state = intent.getStringExtra(TelephonyManager.EXTRA_STATE);
String incomingNumber = intent.getStringExtra(TelephonyManager.EXTRA_INCOMING_NUMBER);
if (state.equals(TelephonyManager.EXTRA_STATE_RINGING)) {
Intent local = new Intent();
local.setAction("service.to.activity.transfer");
local.putExtra("number", incomingNumber);
context.sendBroadcast(local);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}

There is a very simple design pattern you can use here to ease communication between your classes and also decouple your code: publisher/subscriber. My favorite library for this is EventBus:
First, add to your build.gradle file:
compile 'org.greenrobot:eventbus:3.0.0'
Then, create a simple POJO - Plain Old Java Object like this:
public class OnReceiverEvent{
private String phoneNumber;
public OnReceiverEvent(String phone){
this.phoneNumber = phone;
}
public String getPhoneNumber(){
return phoneNumber;
}
}
Next, by making your Receiver class a publisher, and your Activity a subscriber, you should be able to easily pass the information to your activity like this:
//inside your PhoneStateReceiver class when you want to pass info
EventBus.getDefault().post(new OnReceiverEvent(phoneNumber));
Next, inside your activity, simply do this:
//onStart
#Override
public void onStart(){
super.onStart();
EventBus.getDefault().register(this);
}
//onStop
#Override
public void onStop(){
super.onStop();
EventBus.getDefault().unregister(this);
}
Finally, handle the posted data i.e phoneNumber value:
#Subscribe
public void onPhoneNumberReceived(OnReceiverEvent event){
//get the phone number value here and do something with it
String phoneNumber = event.getPhoneNumber();
//display or something?
}
UPDATE
If you have another Event that you want this activity to subscribe to, simply create a method like you did in the first one using the #Subscribe annotation.
#Subscribe
public void onSomeOtherEvent(EventClassName event){
//get the variables here as usual;
}
This is the easiest way to pass the data from your receiver to your activity without having to worry about starting the activity over and over!
I hope this helps and good luck!

So I understand you don't want to recreate your Activity everytime.
In your Intent changing this flag will help you :
intent_phonenum.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
In Intent class if you read method summary of FLAG_ACTIVITY_CLEAR_TOP:
If set, and the activity being launched is already running in the
current task, then instead of launching a new instance of that activity,
all of the other activities on top of it will be closed and this Intent
will be delivered to the (now on top) old activity as a new Intent. (you can read more ...)
In this case: If your app is running and you have an Activity instance then Intent will not recreate your Activity. But assume that your app is in closed state and when BroadcastReceiver triggered, the Intent will create new Activity because you don't have instance of that Activity.
#Edit :
You can specify special Intent like that in your BroadcastReceiver:
public void onReceive(Context context, Intent intent) {
Bundle extras = intent.getExtras();
Intent i = new Intent("mycustombroadcast");
i.putExtra("phone_num", incomingNumber);
context.sendBroadcast(i);
}
Then in your Activity inside onCreate() register receiver like that :
BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
Bundle bundle = intent.getExtras();
int incoming_number= bundle.getInt("phone_num");
Log.e("incoming number", "" + incoming_number);
}
};
//then register receiver like that :
registerReceiver(broadcastReceiver, new IntentFilter("mycustombroadcast"));
You can unregister Receiver in onDestroy() : unregisterReceiver(broadcastReceiver);
Also another way is overriding onNewIntent() in your Activity:
#Override
protected void onNewIntent(Intent intent) {
//your intent is here, you can do sth.
super.onNewIntent(intent);
}

How to Start same activity with different data from Broadcast Receiver?

I have 1 activity that I would like to start at different times with different variables from a Broadcast Receiver.
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (action.equalsIgnoreCase("tv.abcd.v4.ORIGINAL_VIDEO_SCENE")){
channelName = intent.getExtras().getString("com.abcd.Channel");
JSONObject json = new JSONObject(intent.getExtras().getString("com.abcd.Data"));
String incomingScene = json.getString("url");
scene.putExtra("channel", channelName);
scene.putExtra("url", incomingScene);
scene.addFlags(Intent.FLAG_FROM_BACKGROUND);
scene.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
scene.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(scene);
}
I have the code to start the activity via Intent and in the activity receiver the extras to make data appear.
Intent intent = getIntent();
sceneUrl = intent.getStringExtra("url");
Log.d("Image.incomingscene.url",sceneUrl);
channelName = intent.getStringExtra("channel");
Log.d("Image.incomingSceneAvatar",networkAvatar);
image = (ImageView)findViewById(R.id.imageView1);
image.setScaleType(ScaleType.FIT_CENTER);
progressBar = (ProgressBar)findViewById(R.id.progressBar1);
Picasso.with(this).load(sceneUrl).skipMemoryCache().fit().into(image, new EmptyCallback() {
});
Now after that I want to start the same activity again from the Broadcast Reciever with different data. So i want the previous activity to get out the way and allow this new instance to start up.
How to accomplish this feat?

register another broadcast receiver from the activity. Then, when you want to kill it, send a broadcast message from the broadcast receiver that you mentioned .
In your broadcastReceiver do something like the following :
public static final String CLOSE_Activity= "com.mypackage.closeactivity";
and in yopr OnReceive method do like the following :
#Override
public void onReceive(Context context, Intent intent) {
System.out.println("HIT OUTGOING");
Intent i = new Intent();
i.setAction(CLOSE_Activity);
context.sendBroadcast(i);
}
then in your activity craete a receviver and register it in the onResume method and unregeister it in the onPause method , like the following :
private BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(RECEIVER_Class.CLOSE_Activity)) {
finish();
}
}
}
activity onResume method :
#Override
public void onResume() {
registerReceiver(broadcastReceiver, new IntentFilter(RECEIVER_Class.CLOSE_Activity));
}
activity onPause method :
#Override
public void onPause() {
super.onPause();
unregisterReceiver(receiver);
}
Please give me some feedback
Hope that helps .

call activity method from broadcast receiver

In the main activity, a layout is loaded that has some input fields and a submit button. When the submit button is clicked, the onClick handler method sends an sms back to the same mobile number :
SmsManager sms = SmsManager.getDefault();
sms.sendTextMessage(number, null, "hi", null, null);
There is a broadcast receiver defined that intercepts the message :
public class SmsReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context context, Intent intent) {
Bundle pdusBundle = intent.getExtras();
Object[] pdus=(Object[])pdusBundle.get("pdus");
SmsMessage messages=SmsMessage.createFromPdu((byte[]) pdus[0]);
if(messages.getMessageBody().contains("hi")){
abortBroadcast();
}
}
}
Now, from the broadcast receiver, I want to call a function(with parameter), which is within my main activity. Is that possible? If yes, what kind of code should i add in my broadcast receiver ?

Thanks #Manishika. To elaborate, making the Broadcastreceiver dynamic, instead of defining it in the manifest, did the trick. So in my broadcast receiver class, i add the code :
MainActivity main = null;
void setMainActivityHandler(MainActivity main){
this.main=main;
}
In the end of the onReceive function of the BroadcastReceiver class, I call the main activity's function :
main.verifyPhoneNumber("hi");
In the main activity, I dynamically define and register the broadcast receiver before sending the sms:
SmsReceiver BR_smsreceiver = null;
BR_smsreceiver = new SmsReceiver();
BR_smsreceiver.setMainActivityHandler(this);
IntentFilter fltr_smsreceived = new IntentFilter("android.provider.Telephony.SMS_RECEIVED");
registerReceiver(BR_smsreceiver,fltr_smsreceived);

Pass your Activity's context to BroadcastReceiver's contructor.
public class SmsReceiver extends BroadcastReceiver{
MainActivity ma; //a reference to activity's context
public SmsReceiver(MainActivity maContext){
ma=maContext;
}
#Override
public void onReceive(Context context, Intent intent) {
ma.brCallback("your string"); //calling activity method
}
}
and in your MainActivity
public class MainActivity extends AppCompatActivity {
...
public void onStart(){
...
SmsReceiver smsReceiver = new SmsReceiver(this); //passing context
LocalBroadcastManager.getInstance(this).registerReceiver(smsReceiver,null);
...
}
public void brCallback(String param){
Log.d("BroadcastReceiver",param);
}
}
hope it helps

use this
Intent intent=new Intent();
intent.setClassName("com.package.my", "bcd.class");
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(intent);

You can't directly call a function in your Activity unless it's a public static method but don't do so. I recommend this:
#Override
public void onReceive(Context context, Intent intent) {
Bundle bundle = new Bundle();
bundle.putExtraString("ACTION", "stopBroadcast");
// ### put what ever you need into the bundle here ###
Intent intent = new Intent();
intent.setClassName(context, "activity.class");
intent.putExtras(bundle);
context.startActivity(intent);
}
And then from your Activity's onCreate() get Bundle and take your actions as needed.

It's a little bit late, but nobody mentioned it.
There is no need for passing activity.
As #faizal specifies, IntentService is started from MainActivity, so, context in onReceive() is already instance of MainActivity.
It is enough to write smth like this:
#Override
public void onReceive(Context context, Intent intent) {
if(context instanceof MainActivity) {
MainActivity activity = (MainActivity) context;
}
}

sending intent extras from service to activity

I have a service that listens for (ON_BATTERY_CHANGE), then onReceive service sends a Broadcast to My MainActivity. The problem is that I somehow can't get them from service to my main activity. Code: Main Activity:
public class MainActivity extends Activity
private BroadcastReceiver batteryReceiverService;
private TextView text2;
....
protected void onCreate(Bundle savedInstanceState) {
text2=(TextView)findViewById(R.id.TV_text2);
batteryReceiverService = new BroadcastReceiver(){
#Override
public void onReceive(Context context, Intent intent) {
text2.setText("left: "+intent.getStringExtra("H")+" hours "+intent.getStringExtra("M")+" minute(s)");
Log.e("text2","text2 HHH " +intent.getStringExtra("H")); //log shows 0
Log.e("text2","text2 MMM " +intent.getStringExtra("H")); // log shows 0
}
};
registerReceiver(batteryReceiverService, new IntentFilter(UltimateBatterySaverService.BROADCAST_ACTION));
....
#Override
protected void onDestroy() {
unregisterReceiver(batteryReceiverService);
super.onDestroy();
}
Service:
public class UltimateBatterySaverService extends Service {
private Intent intent;
static final String BROADCAST_ACTION = "lt.whitegroup.ultimatebatterysaver";
private BroadcastReceiver batteryLevelReceiver;
....
public void onCreate() {
super.onCreate();
intent = new Intent(BROADCAST_ACTION);
}
#Override
public void onDestroy() {
unregisterReceiver(batteryLevelReceiver);
super.onDestroy();
}
IntentFilter batteryLevelFilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
batteryLevelReceiver = new BroadcastReceiver(){
#Override
public void onReceive(Context context, Intent intent){
// Receiving data, calculating and etc
averageChargingH=timeAllInHours;
averageChargingM=timeAllInMinutes;
// to put extras and send broadcast
does();
......
public void does(){
String strLong = Long.toString(averageChargingH);
String strLong2 = Long.toString(averageChargingM);
Log.e("cccccc","strLong h "+strLong); // getting good value not 0(everything ok)
Log.e("cccccc","strLong2 m"+strLong2); // getting good value not 0(everything ok)
intent.putExtra("H", strLong);
intent.putExtra("M", strLong2);
sendBroadcast(intent);
}
Any ideas why my information is not transfered correctly?

The does() method seems to be using variables in the same scope as onReceive so I'm guessing that the intent variable in does() is actually the Intent passed in from onReceive.
Try adding some logging before sending the broadcast to check if the action of the intent is correct, or simply create the broadcast intent in the onReceive method and name it intent2.