java.lang.NullPointerException: Attempt to invoke virtual method 'io.flutter.plugin.common.PluginRegistry$RequestPermissionsResultListener com.lyokone.location.FlutterLocationService.getServiceRequestPermissionsResultListener()' on a null object reference

[HAFIZkhan-source]

Describe the bug
App crashing on very first app open

Tested on:

• Android OS 13, Samsung Galaxy M13

Other plugins:

• List of others Flutter plugins that could interfere

Additional logs
D/FlutterGeolocator(20666): Attaching Geolocator to activity
D/FlutterGeolocator(20666): Detaching Geolocator from activity
E/AndroidRuntime(20666): FATAL EXCEPTION: main
E/AndroidRuntime(20666): Process: com.skieats.owner, PID: 20666
E/AndroidRuntime(20666): java.lang.RuntimeException: Unable to destroy activity {com.skieats.owner/com.skieats.owner.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'io.flutter.plugin.common.PluginRegistry$RequestPermissionsResultListener com.lyokone.location.FlutterLocationService.getServiceRequestPermissionsResultListener()' on a null object reference
E/AndroidRuntime(20666): at android.app.ActivityThread.performDestroyActivity(ActivityThread.java:6080)
E/AndroidRuntime(20666): at android.app.ActivityThread.handleDestroyActivity(ActivityThread.java:6113)
E/AndroidRuntime(20666): at android.app.ActivityThread.handleRelaunchActivityInner(ActivityThread.java:6460)
E/AndroidRuntime(20666): at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:6341)
E/AndroidRuntime(20666): at android.app.servertransaction.ActivityRelaunchItem.execute(ActivityRelaunchItem.java:71)
E/AndroidRuntime(20666): at android.app.servertransaction.ActivityTransactionItem.execute(ActivityTransactionItem.java:45)
E/AndroidRuntime(20666): at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
E/AndroidRuntime(20666): at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
E/AndroidRuntime(20666): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2574)
E/AndroidRuntime(20666): at android.os.Handler.dispatchMessage(Handler.java:106)
E/AndroidRuntime(20666): at android.os.Looper.loopOnce(Looper.java:226)
E/AndroidRuntime(20666): at android.os.Looper.loop(Looper.java:313)
E/AndroidRuntime(20666): at android.app.ActivityThread.main(ActivityThread.java:8757)
E/AndroidRuntime(20666): at java.lang.reflect.Method.invoke(Native Method)
E/AndroidRuntime(20666): at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:571)
E/AndroidRuntime(20666): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1067)
E/AndroidRuntime(20666): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'io.flutter.plugin.common.PluginRegistry$RequestPermissionsResultListener com.lyokone.location.FlutterLocationService.getServiceRequestPermissionsResultListener()' on a null object reference
E/AndroidRuntime(20666): at com.lyokone.location.LocationPlugin.dispose(LocationPlugin.java:117)
E/AndroidRuntime(20666): at com.lyokone.location.LocationPlugin.detachActivity(LocationPlugin.java:56)

[gyy19931212]

May I ask how to solve it

[bartekpacia]

What version of the plugin are you using?

Please attach a Minimal, Reproducible Example.

[LorenzSchueler]

I'm facing a similar issue with the current version (5.0.2+1).

PlatformException(error, Attempt to write to field 'io.flutter.plugin.common.EventChannel$EventSink com.lyokone.location.FlutterLocation.events' on a null object reference in method 'void com.lyokone.location.StreamHandlerImpl.onListen(java.lang.Object, io.flutter.plugin.common.EventChannel$EventSink)', null, null)

The error only occurs when using location from a separate isolate (in my case I try to start a location stream from a separate foreground service using flutter_foreground_task). When using it from the main isolate everything is fine.

[HAFIZkhan-source]

@bartekpacia I am using location: ^5.0.1

[bartekpacia]

Thanks for explaining. Could you attach minimal, reproducible examples?

[LorenzSchueler]

@bartekpacia sure.

pressing the activate button works, pressing activate on other isolate does not work

import 'dart:async';
import 'dart:isolate';

import 'package:flutter/material.dart';
import 'package:flutter_foreground_task/flutter_foreground_task.dart';
import 'package:location/location.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  MyApp({super.key});

  final location = Location();

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            FilledButton(
              onPressed: activateLocation,
              child: const Text("activate"),
            ),
            FilledButton(
              onPressed: activateLocationOtherIsolate,
              child: const Text("activate on other isolate"),
            ),
          ],
        ),
      ),
    );
  }

  Future<void> activateLocation() async {
    await location.requestPermission();
    await location.enableBackgroundMode();
    final locationSubscription = location.onLocationChanged.listen(print);
    Timer(const Duration(minutes: 5), () {
      locationSubscription.cancel();
    });
  }

  Future<void> activateLocationOtherIsolate() async {
    // request permissions on main isolate
    await location.requestPermission();

    FlutterForegroundTask.init(
      androidNotificationOptions: AndroidNotificationOptions(
        channelId: 'notification_channel_id',
        channelName: 'Foreground Notification',
      ),
      iosNotificationOptions: const IOSNotificationOptions(),
      foregroundTaskOptions: ForegroundTaskOptions(
        interval: const Duration(minutes: 1).inMilliseconds,
      ),
    );

    await FlutterForegroundTask.startService(
      notificationTitle: "title",
      notificationText: "text",
      callback: startCallback,
    );
  }
}

@pragma('vm:entry-point')
void startCallback() {
  FlutterForegroundTask.setTaskHandler(MyTaskHandler());
}

class MyTaskHandler extends TaskHandler {
  @override
  Future<void> onStart(DateTime timestamp, SendPort? sendPort) async {}

  @override
  Future<void> onRepeatEvent(DateTime timestamp, SendPort? sendPort) async {
    final location = Location();
    await location.enableBackgroundMode();
    final locationSubscription = location.onLocationChanged.listen(print);
    Timer(const Duration(minutes: 5), () {
      locationSubscription.cancel();
    });
  }

  @override
  Future<void> onDestroy(DateTime timestamp, SendPort? sendPort) async {}
}

add to AndroidManifest.xml:

<service
            android:name="com.pravera.flutter_foreground_task.service.ForegroundService"
            android:stopWithTask="true" />

dependencies:

location: ^5.0.2+1
flutter_foreground_task: ^6.0.0+1

[LorenzSchueler]

@bartekpacia It seems to be an initialization problem. The FlutterLocation objects in StreamHandlerImpl and MethodCallHandlerImpl are null. I've not yet been able to pinpoint he problem. But as I wrote earlier, this is only the case if you use the package from a different isolate. Although I know that work on develop is currently not planned, I just wanted to mention that with develop this problem does not occur.
Any ideas how to fix it?

[predictron-cloud]

@Lyokone , I faced this issue on Android API 33. Could you please merge the fix #889 ? According to the code changes it should be ok.

[Sofstica-Abdul-Bari]

@bartekpacia @Lyokone any update on this?

[bartekpacia]

Is #889 the fix for this?

Would you be able to use a version of this package from #889 and let me know if it works correctly, fixes this bug, and doesn't crash? Thank you in advanace 🙏🏻

[Sofstica-Abdul-Bari]

Tried running the code from commit hash code
location:
git:
url: https://github.com/Lyokone/flutterlocation.git
ref: 9e45657
path: packages/location/

The issue still exists. I tried using flutter clean and running pub get again.
Also, do let me know if I am doing it in a wrong way!

[bartekpacia]

Thanks for checking. I'll be happy to merge and release a fix but I don't have time to work on this. All contributions are welcome.

[ardeshir-33033]

this issue came up to me as well.
I use version 6.0.1

[flightcom]

Having the issue as well when running it from an isolate using flutter_foreground_task.
I tried the mentioned commit but same issue.