Firebase - Activity restarts when user clicks notification

Question

I'm coding an app that uses firebase for implementing notifications. In my MainActivity I have a WebView with some url, but the thing is that when the user clicks on a notification, I want to open MainActiviy with a diferent url in the WebView. I've read a lot and I've added a bundle to the intent (that opens MainActivity when a notification is clicked) which cointains the desired url. But when I click on the notification, MainActivity restarts, I mean, it doesn't go to onNewIntent, but instead, it runs onCreate. This is how I implemented it:

private void sendNotification(String messageTitle, String messageBody, String url){

    Intent intent = new Intent(this, MainActivity.class);
    intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

    //This adds the url to the intent
    if(!url.equals("")){
        Bundle bundle = new Bundle();
        bundle.putString("url", url);
        intent.putExtras(bundle);
    }

    PendingIntent pendingIntent = PendingIntent.getActivity(this, 0,intent, PendingIntent.FLAG_ONE_SHOT);

    String channelId = getString(R.string.default_notification_channel_id);

    NotificationCompat.Builder notificationBuilder = new NotificationCompat
            .Builder(this, channelId)
            .setContentTitle(messageTitle)
            .setContentText(messageBody)
            .setPriority(NotificationCompat.PRIORITY_DEFAULT)
            .setAutoCancel(true)
            .setSmallIcon(R.drawable.ic_launcher_background)
            .setContentIntent(pendingIntent);

    NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

    if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.O){
        NotificationChannel channel = new NotificationChannel(channelId,
                "Notification channel",
                NotificationManager.IMPORTANCE_DEFAULT);
        notificationManager.createNotificationChannel(channel);
    }

    notificationManager.notify(0, notificationBuilder.build());

}

onNewIntent I have this:

Bundle bundle = intent.getExtras();
        if (bundle != null) {
            String url = bundle.getString("url");
            mWebView.loadUrl(url);
        }

But when the notification is clicked, the activity just restarts, so it does not run onNewIntent, and log gives me this error:

02-08 12:51:12.140 19056-19056/com.example.android.app E/ActivityThread: Activity com.example.android.app.MainActivity has leaked IntentReceiver com.example.android.app.MainActivity$1@d7818db that was originally registered here. Are you missing a call to unregisterReceiver()?
android.app.IntentReceiverLeaked: Activity com.example.android.app.MainActivity has leaked IntentReceiver com.example.android.app.MainActivity$1@d7818db that was originally registered here. Are you missing a call to unregisterReceiver()?
    at android.app.LoadedApk$ReceiverDispatcher.<init>(LoadedApk.java:999)
    at android.app.LoadedApk.getReceiverDispatcher(LoadedApk.java:795)
    at android.app.ContextImpl.registerReceiverInternal(ContextImpl.java:1329)
    at android.app.ContextImpl.registerReceiver(ContextImpl.java:1309)
    at android.app.ContextImpl.registerReceiver(ContextImpl.java:1303)
    at android.content.ContextWrapper.registerReceiver(ContextWrapper.java:554)
    at com.example.android.app.MainActivity.onCreate(MainActivity.java:264)
    at android.app.Activity.performCreate(Activity.java:6367)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1110)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2404)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2511)
    at android.app.ActivityThread.access$900(ActivityThread.java:165)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1375)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:150)
    at android.app.ActivityThread.main(ActivityThread.java:5621)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:794)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:684)

I read on a similar question on stackoverflow was to unregister a BroadCastReceiver to fix this error, but I'm a little bit lost on how to do it.

I've tried changing the intent on sendNotification to

Intent intent = new Intent("android.intent.action.MAIN");

but in that case when the user clicks the notification it doesn't do anything.

Does anyone knows how to fix it so the url loads when a user clicks? Thanks you in advance

Answer 1

From the Android docs it states this:

If it has declared its launch mode to be "multiple" (the default) and you have not set FLAG_ACTIVITY_SINGLE_TOP in the same intent, then it will be finished and re-created; for all other launch modes or if FLAG_ACTIVITY_SINGLE_TOP is set then this Intent will be delivered to the current instance's onNewIntent().

So looks like setting the FLAG_ACTIVITY_SINGLE_TOP flag when you create the new intent should solve and run the onNewIntent() method, instead of re-creating the application.

Answer 2

create a method like this

private PendingIntent retrievePlaybackAction(final String action) {
    Intent intent = new Intent(action);
    return PendingIntent.getBroadcast(this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
}

Now add your intent like this

builder.setContentIntent(retrievePlaybackAction("OPEN_MAIN")); //change action text as you want

Create a simple class NotificationReceiver which I guess you have created, Now create object of this class from where you are sending notifications

private NotificationReceiver notificationReceiver;

In onCreate() register your receivers

notificationReceiver = new NotificationReceiver();

IntentFilter intentFilterNextClick = new IntentFilter("OPEN_MAIN");

registerReceiver(notificationReceiver, intentFilterNextClick); 
//can create exception, better to surround with try catch

In onDestroy() unregister your Receiver

unregisterReceiver(notificationReceiver); 
//can create exception, better to surround with try catch

To open or do some action add this in your Receiver

@Override
public void onReceive(Context context, Intent intent) {
    Log.e(TAG, "onReceive: received " + intent.getAction());

    String action = intent.getAction();

    //no need to create switch you can also use if
    switch (action) {
        case "OPEN_MAIN":
            openMain();
            break;
    }

}

//here is openMain();
private void openMain(Context context) {
    Intent openMainIntent = new Intent(context, MainActivity.class);
    openMainIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); //this flag is important
    context.startActivity(openMainIntent);
}

This will also work if the app is minimized or closed

Hope this will help!

Please ask if you need more help!