Crash when using in combination with firebase_messaging

[Niek]

When using firebase_messaging, you need to to add your own Application class that implements PluginRegistrantCallback. However, this causes WiFiFlutter to crash with the following trace:

E/MethodChannel#plugins.flutter.io/firebase_messaging(10125): Failed to handle method call
E/MethodChannel#plugins.flutter.io/firebase_messaging(10125): java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.app.Activity.getApplicationContext()' on a null object reference
E/MethodChannel#plugins.flutter.io/firebase_messaging(10125):   at com.alternadom.wifiiot.WifiIotPlugin.<init>(WifiIotPlugin.java:65)
E/MethodChannel#plugins.flutter.io/firebase_messaging(10125):   at com.alternadom.wifiiot.WifiIotPlugin.registerWith(WifiIotPlugin.java:76)
E/MethodChannel#plugins.flutter.io/firebase_messaging(10125):   at io.flutter.plugins.GeneratedPluginRegistrant.registerWith(GeneratedPluginRegistrant.java:26)
E/MethodChannel#plugins.flutter.io/firebase_messaging(10125):   at com.mypack.myapp.Application.registerWith(Application.java:18)
E/MethodChannel#plugins.flutter.io/firebase_messaging(10125):   at io.flutter.plugins.firebasemessaging.FlutterFirebaseMessagingService.startBackgroundIsolate(FlutterFirebaseMessagingService.java:164)
E/MethodChannel#plugins.flutter.io/firebase_messaging(10125):   at io.flutter.plugins.firebasemessaging.FirebaseMessagingPlugin.onMethodCall(FirebaseMessagingPlugin.java:134)
E/MethodChannel#plugins.flutter.io/firebase_messaging(10125):   at io.flutter.plugin.common.MethodChannel$IncomingMethodCallHandler.onMessage(MethodChannel.java:222)
E/MethodChannel#plugins.flutter.io/firebase_messaging(10125):   at io.flutter.embedding.engine.dart.DartMessenger.handleMessageFromDart(DartMessenger.java:96)
E/MethodChannel#plugins.flutter.io/firebase_messaging(10125):   at io.flutter.embedding.engine.FlutterJNI.handlePlatformMessage(FlutterJNI.java:656)
E/MethodChannel#plugins.flutter.io/firebase_messaging(10125):   at android.os.MessageQueue.nativePollOnce(Native Method)
E/MethodChannel#plugins.flutter.io/firebase_messaging(10125):   at android.os.MessageQueue.next(MessageQueue.java:336)
E/MethodChannel#plugins.flutter.io/firebase_messaging(10125):   at android.os.Looper.loop(Looper.java:174)
E/MethodChannel#plugins.flutter.io/firebase_messaging(10125):   at android.app.ActivityThread.main(ActivityThread.java:7356)
E/MethodChannel#plugins.flutter.io/firebase_messaging(10125):   at java.lang.reflect.Method.invoke(Native Method)
E/MethodChannel#plugins.flutter.io/firebase_messaging(10125):   at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
E/MethodChannel#plugins.flutter.io/firebase_messaging(10125):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)

It's coming from this call: https://github.com/alternadom/WiFiFlutter/blob/a8bb37f87425e45d2947e6c7c4e8b9416c886364/android/src/main/java/com/alternadom/wifiiot/WifiIotPlugin.java#L65

[florian-guillemard]

Hi,

Seems your poActivity is null, can you show me your call to your WifiIotPlugin constructor ?

[Niek]

The WifiIotPlugin contructor is called from registerWith():
https://github.com/alternadom/WiFiFlutter/blob/a8bb37f87425e45d2947e6c7c4e8b9416c886364/android/src/main/java/com/alternadom/wifiiot/WifiIotPlugin.java#L76

This is my Application.java, it is missing anything? Maybe add a call to onCreate()?

package com.my.app;

import io.flutter.app.FlutterApplication;
import io.flutter.plugin.common.PluginRegistry;
import io.flutter.plugin.common.PluginRegistry.PluginRegistrantCallback;
import io.flutter.plugins.GeneratedPluginRegistrant;
import io.flutter.plugins.firebasemessaging.FlutterFirebaseMessagingService;

public class Application extends FlutterApplication implements PluginRegistrantCallback {
    @Override
    public void onCreate() {
        super.onCreate();
        FlutterFirebaseMessagingService.setPluginRegistrant(this);
    }

    @Override
    public void registerWith(PluginRegistry registry) {
        GeneratedPluginRegistrant.registerWith(registry);
    }
}

[daadu]

@Niek @Alternadom Facing the same issue. Did you find any solution?

[daadu]

flutter/flutter#22117
flutter/flutter#26003

[daadu]

A similar problem occurred with android_alarm_manager and google_maps_flutter

This was the workaround they implemented for it: flutter/plugins#1255

In conclusion:

A plugin method channel can be called without activity. Hence not registering plugin when activity is null is the workaround [as used in the PR mentioned]

[daadu]

I confirm that this fixes the issue.

@Niek Please try and report

Put this in pubspec.yaml

dependencies:
  flutter:
    sdk: flutter
  firebase_core: 0.4.0+9
  firebase_messaging: ^5.1.6
  wifi_iot:
    git:
      #FIXME https://github.com/alternadom/WiFiFlutter/issues/45
      #url: "https://github.com/alternadom/WiFiFlutter.git"
      url: "https://github.com/daadu/WiFiFlutter.git"
      ref: "#45"

[Niek]

Thanks @daadu - I can confirm this fixes the issue! @Alternadom can you merge the change?