Why are multiple messages being send inside BroadcastReceiver when I use it to detect sim change?

Question

Basically what I'm trying to do is when I change the sim in my phone I want to send a message to a number that my sim has been changed. Here's my manifest: I have added the permission to send sms and intent to track the sim change

<uses-permission android:name="android.permission.SEND_SMS" />
   <receiver android:name=".SimChangeReceiver">
            <intent-filter>
                <action android:name="android.intent.action.SIM_STATE_CHANGED"/>
            </intent-filter>
        </receiver>

Here's the broadcast receiver I used.

public class SimChangeReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {

        Toast.makeText(context, "SIM state changed", Toast.LENGTH_SHORT).show();
        SmsManager smsmanager=SmsManager.getDefault();
        smsmanager.sendTextMessage(mynumber,null,"sim has been changed",null,null);

    }
}

The problem is when I change the sim, the Toast happens couple of times and the message gets send 4 times exactly to mynumber. Why is it happening? Can I put some limit to it to just send the message only once? I'm new to Android. So forgive me if I can't find the problem.

score 0 · Answer 1 · edited May 23 '17 at 12:25

The broadcast with action android.intent.action.SIM_STATE_CHANGED is fired multiple times when a SIM card is changed.

You will need to add a logic to suppress the duplicate calls when you are doing something critical like sending a message.

Refer this for more information: https://stackoverflow.com/a/10553473/1468093

EDIT:

The approach you should take to damp multiple broadcasts highly depends on your application for what you are trying to do. I can think of the following approaches:

You may damp it by storing the history and checking if the message was sent within last 5 seconds or whatever is your threshold

@Override
public void onReceive(Context context, Intent intent) {
    if (System.currentTimeMillis() - db.getLastActionTakenTime() > 5 * SECONDS) {
        // Do the thing

        db.saveActionTakenTime();
    }
}

Start a new service to do what you want only if the service is not already started, this will ensure that the message is sent just once.

@Override
public void onReceive(Context context, Intent intent) {
    new Handler().postDelayed(new Runnable(
        @Override
        public void run() {
            doTheThing(context);
        }
    ), 2 * SECONDS);
}

public synchronized void doTheThing(Context context) {
    Intent serviceIntent = new Intent(context, MyActionService.class);

    if (peekService(serviceIntent) == null) { // To check if the service is not started
        context.startService(serviceIntent);
    }
}


public class MyActionService extends Service {

    public int onStartCommand() {
        // Do the thing

        return super.onStartCommand();
    }
}

Note: Assuming your task takes at least 2 seconds to complete

Can I really declare an intent in the manifest in the format android.intent.action.SIM_STATE_CHANGED with extras: ss = READY, reason = null ? Is there really a keyword extras and reason? — Asok, Apr 24 '17 at 15:46
Nope, there isn't. And you cannot even trustfully put a check for one of the extra values as *It is possible that different manufacturers and different models behave differently* — Kamran Ahmed, Apr 25 '17 at 04:46
I cannot think of any better logic than damping multiple calls within a few seconds by keeping a record of when it was fired last. — Kamran Ahmed, Apr 25 '17 at 04:48

Why are multiple messages being send inside BroadcastReceiver when I use it to detect sim change?

1 Answers1