Registering and unregistering BroadcastReceiver in a fragment

Question

My app has an action bar with 3 fragment tabs. In the second fragment I register and unregister a BroadcastReceiver. I unregister the receiver in onPause and register it in onCreateView and in onResume.

getActivity().registerReceiver(this.batteryInfoReceiver, new IntentFilter(Intent.ACTION_BATTERY_CHANGED));

and

getActivity().unregisterReceiver(batteryInfoReceiver);

1) Is it all right to register the same reciever twice (in onCreateView and onResume)?(is it harmless?)

2) Is it enough to just register the reciever in onResume?

I got an unregister error when I was trying it on a fragment. The problem I faced was that - I was trying to unregister twice. Once on onDestroy() and once on onPause(). I also did register once on onCreate() and once on onResume(). Later on looking at the life-cycle of the fragment, I found out I just need to register on onResume() and unregister on onPause(). This is enough to register and unregister on a fragment. Hope this helps someone doing broadcast with fragments. :) — Dinesh, Jul 13 '17 at 14:11

score 155 · Accepted Answer · edited Aug 24 '15 at 11:15

Have a look at life-cycle of Fragments:

onCreateView(): The system calls this when it's time for the fragment to draw its user interface for the first time. To draw a UI for your fragment, you must return a View from this method that is the root of your fragment's layout. You can return null if the fragment does not provide a UI.

onResume(): The fragment is visible in the running activity

onPause(): This is usually where you should commit any changes that should be persisted beyond the current user session (because the user might not come back).

Conclusion:

So it is better to register the receiver only inside onResume() and unregister inside onPause() because onCreateView() deals with view hierarchy only. It has nothing to do with receiver. So it is not harmful but surely it is useless.

I hope it will be helpful!!

Stefan Ronnkvist · Answer 2 · 2017-02-03T21:07:19.327

Here is code that works for me:

Inside layout:

<Button
    android:id="@+id/button2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:onClick="sendInternalBroadcast"
    android:text="Broadcast"/>

Fragment Layout:

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:gravity="center">

    <TextView
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        android:text="Fragment One"
        android:id="@+id/fragmentoneTextView1"/>

</LinearLayout>

inside Main Activity:

    public void sendInternalBroadcast(View view)
{
    Intent intent = new Intent();
intent.setAction("com.codingbadly.stefanronnkvist.simplebroadcastreceiver.setup");
    intent.putExtra("From", "sendInternalBroadcast");
    sendBroadcast(intent);
}

Fragment:

import android.app.*;
import android.content.*;
import android.os.*;
import android.view.*;
import android.widget.*;

public class FragmentOne extends Fragment
{
    View view;
    Context _context;
    PendingIntent pi;
    BroadcastReceiver br;
    AlarmManager am;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        view = inflater.inflate(R.layout.fragmentone, container, false);
        setup();
        return view;
    }

    @Override
    public void onAttach(Context context)
    {
        super.onAttach(context);
        _context = context;
    }

    @Override
    public void onDestroyView()
    {
        super.onDestroyView();
        _context.unregisterReceiver(br);
    }


    private void setup()
    {
        br = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent i)
            {
                TextView tv = (TextView)view.findViewById(R.id.fragmentoneTextView1);
                tv.setText("onReceive");
            }
        };
        _context.registerReceiver(br, new IntentFilter("com.codingbadly.stefanronnkvist.simplebroadcastreceiver.setup"));
        pi = PendingIntent.getBroadcast(_context, 0, new Intent("com.codingbadly.stefanronnkvist.simplebroadcastreceiver.setup"), 0);
        am = (AlarmManager)(_context.getSystemService(Context.ALARM_SERVICE));
    }
}

Good Luck.. Stefan Ronnkvist

Your solution is great! And please correct your profile, man. user1579736 is not cool But you are! — NoWar, Dec 14 '17 at 04:21
I think the only question here is `when` to register the receiver. Make your answer great and clear, don't dump all your code, especially the UI files. — Vince, Jul 15 '21 at 17:35

score 5 · Answer 3 · edited Sep 04 '18 at 08:47

5

OnResume Register:

context.registerReceiver(receiver,IntentFilter(BroadCastAction.action_success))

onPause unRegister :

context.unregisterReceiver(mContactBroadCastReceiver);

edited Sep 04 '18 at 08:47

prashant17

1,520
3
14
23

answered Feb 23 '18 at 06:33

Pradeep Bishnoi

1,843
2
22
26

Aziz · Answer 4 · 2020-12-11T05:53:44.980

2

With Fragment, you will end up getting the exception Receiver not registered in some cases as in my case.

To resolve this, I used

 LocalBroadcastManager.getInstance(ctx).registerReceiver(myReceiver,IntentFilter(...))

instead of

 activity.registerReceiver(paxAmountReceiver,IntentFilter(...))

Similarly to unregister, use in onDestroyView() (For Eg.)

LocalBroadcastManager.getInstance(ctx).unregister(myReceiver)

edited Dec 11 '20 at 05:53

answered Dec 11 '20 at 05:43

Aziz

1,976
20
23

Isn't LocalBroadcastManager used only for when you use the Intents within your own app, and not between apps? – android developer Oct 07 '22 at 21:48

Registering and unregistering BroadcastReceiver in a fragment

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