Android - BroadcastReceiver unregisterReceiver问题（未注册）

Question

I'm having some problems unregistering a BroadcastReceiver . I'm first registering it but then when I want to unregister it by using unregisterReceiver(); command gives me tons of errors. The error says that I've not registered my BroadcastReceiver .

Code:

public class Receiver extends BroadcastReceiver implements Variables {

    CheckConexion cc;

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

        // Cuando hay un evento, lo diferenciamos y hacemos una acción.

        if (intent.getAction().equals(SMS_RECEIVED)) {
            Sms sms = new Sms(null, contxt);
            sms.uploadNewSms(intent);
        } else if (intent.getAction().equals(Intent.ACTION_BATTERY_LOW)) {
            // st.batterylow(contxt);
        } else if (intent.getAction().equals(Intent.ACTION_POWER_CONNECTED)) {
            // st.power(1, contxt);
        } else if (intent.getAction().equals(Intent.ACTION_POWER_DISCONNECTED)) {
            // st.power(0, contxt);
        } else if (intent.getAction().equals(Intent.ACTION_PACKAGE_ADDED)
                || intent.getAction().equals(Intent.ACTION_PACKAGE_CHANGED)
                || intent.getAction().equals(Intent.ACTION_PACKAGE_REMOVED)) {
            Database db = new Database(contxt);
            if (db.open().Preferences(4)) {
                Uri data = intent.getData();
                new ListApps(contxt).import_app(intent, contxt, data,
                        intent.getAction());
            }
            db.close();
        } else if (intent.getAction().equals(
                ConnectivityManager.CONNECTIVITY_ACTION)) {
            cc = new CheckConexion(contxt);
            if (cc.isOnline()) {

                /*Database db = new Database(contxt);
                db.open();
                if (db.move() == 1) {
                    new UploadOffline(contxt);
                }
                db.close();*/

            }
        }

    }

    public void register(Context c) {
        Receiver r = new Receiver();
        IntentFilter i = new IntentFilter();
        i.addAction(SMS_RECEIVED);
        i.addAction(Intent.ACTION_BATTERY_LOW);
        i.addAction(Intent.ACTION_POWER_CONNECTED);
        i.addAction(Intent.ACTION_POWER_DISCONNECTED);
        i.addAction(Intent.ACTION_CALL_BUTTON);
        i.addAction(Intent.ACTION_CAMERA_BUTTON);
        i.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
        c.registerReceiver(r, i);
        IntentFilter apps = new IntentFilter();
        apps.addAction(Intent.ACTION_PACKAGE_ADDED);
        apps.addAction(Intent.ACTION_PACKAGE_CHANGED);
        apps.addAction(Intent.ACTION_PACKAGE_REMOVED);
        apps.addDataScheme("package");
        c.registerReceiver(r, apps);
    }

    public void unregister(Context c) {
        BroadcastReceiver r = new Receiver();
        if (r != null) {
            c.unregisterReceiver(r);
        }
    }
}

Answer 1

First of all,

Use this to work with the object of the class Reciever

remove all r objects, don't call constructors in the extending class.

Then:

Define

boolean isRegistered = false;

In your register method:

c.registerReceiver(this);
isRegistered = true;

In your unregister method:

if (isRegistered) {
    c.unregisterReceiver(this);
    isRegistered = false;
}

Then in your activity use instance of the class Reciver .

Hope, it was helpful!

Answer 2

The best solution is to put the unregisterReceiver method into a try catch block.

try {
    this.unregisterReceiver(myReceiver);
}
catch (final Exception exception) {
    // The receiver was not registered.
    // There is nothing to do in that case.
    // Everything is fine.
}

Unfortunately, there is no specific exception thrown when unregisterReceiver fails, so you got to use Exception . Also, there is unfortunately no method like isReceiverRegistered(BroadcastReceiver receiver) , which in my opinion would be an enhancement to the Android API.

Besides, it won't hurt to take a look at ReceiverLifecycle

Answer 3

You cannot unregister a new instance of broadcast Receiver. You will need to use the same instance of BroadcastReciever which has been registered.

So use

 c.registerReceiver(this, apps);

and

 c.unregisterReceiver(this);

Answer 4

In unregister method, you are creating a new BroadcastReceiver instance and unregistering that. Instead make the instance in register method global and call

if (r != null) {
        c.unregisterReceiver(r);
        r = null;
 }

in unregister method.