Flutter_file_picker: Error with permission checker and android_alarm_manager

[lucien-theron]

Hi,

I'm getting the following error when I have both file_picker and android_alarm_manager packages installed:

E/MethodChannel#file_picker( 3336): java.lang.NullPointerException: Attempt to invoke virtual method 'int android.content.Context.checkPermission(java.lang.String, int, int)' on a null object reference E/MethodChannel#file_picker( 3336): at androidx.core.content.ContextCompat.checkSelfPermission(ContextCompat.java:544) E/MethodChannel#file_picker( 3336): at com.mr.flutter.plugin.filepicker.FilePickerPlugin.checkPermission(FilePickerPlugin.java:127) E/MethodChannel#file_picker( 3336): at com.mr.flutter.plugin.filepicker.FilePickerPlugin.startFileExplorer(FilePickerPlugin.java:169) E/MethodChannel#file_picker( 3336): at com.mr.flutter.plugin.filepicker.FilePickerPlugin.onMethodCall(FilePickerPlugin.java:119) E/MethodChannel#file_picker( 3336): at io.flutter.plugin.common.MethodChannel$IncomingMethodCallHandler.onMessage(MethodChannel.java:201) E/MethodChannel#file_picker( 3336): at io.flutter.view.FlutterNativeView$PlatformMessageHandlerImpl.handleMessageFromDart(FlutterNativeView.java:188) E/MethodChannel#file_picker( 3336): at io.flutter.embedding.engine.FlutterJNI.handlePlatformMessage(FlutterJNI.java:202) E/MethodChannel#file_picker( 3336): at android.os.MessageQueue.nativePollOnce(Native Method) E/MethodChannel#file_picker( 3336): at android.os.MessageQueue.next(MessageQueue.java:325) E/MethodChannel#file_picker( 3336): at android.os.Looper.loop(Looper.java:142) E/MethodChannel#file_picker( 3336): at android.app.ActivityThread.main(ActivityThread.java:6541) E/MethodChannel#file_picker( 3336): at java.lang.reflect.Method.invoke(Native Method) E/MethodChannel#file_picker( 3336): at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) E/MethodChannel#file_picker( 3336): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

I replicated this in a clean project with the following in the pubspec.yaml:

android_alarm_manager: ^0.4.1+6
file_picker: ^1.3.3

Flutter doctor:
[√] Flutter (Channel stable, v1.2.1, on Microsoft Windows [Version 10.0.17134.648], locale en-ZA) [√] Android toolchain - develop for Android devices (Android SDK version 28.0.3) [√] Android Studio (version 3.3) [√] Android Studio (version 3.0) [√] IntelliJ IDEA Community Edition (version 2018.3) [√] VS Code (version 1.32.3) [√] Connected device (2 available)

Thanks!

[miguelpruivo]

Hi, thanks for reporting.

At a first glance the issue seems to come from ContextCompat.checkSelfPermission(activity, permission); that is called from file_picker layer but then a null pointer happens on the android x compat side. Maybe due to some conflict? Is the alarma manager on the android x as well?

I'm afraid that this can't be handled by file_picker's side.

[lucien-theron]

Hi, yes android_alarm_manager is on android x. I will try and track down the issue as well.

[lucien-theron]

Could I also suggest removing the permission checking, or making it optional. I know it's convenient, but this package should not take on that responsibility in my opinion.

[miguelpruivo]

It needs to check because it will ask for permission if you don’t have it already. That’s the only reason why.

[lucien-theron]

Hi no problem, just a thought. I found the cause to be similar to what happened here: https://github.com/flutter/plugins/pull/1125. Adding the following check to registerWith fixed it:
if (registrar.activity() == null) { return; }

[miguelpruivo]

@lucien-theron is this fixed already? I saw that #156 is already closed. If so, feel free to close this as well.

[lucien-theron]

@miguelpruivo that was for another plugin having the same issue. They fixed it the same way I did in the above PR I made. So if you can merge that PR then we good to go.

[miguelpruivo]

Right. As long as the iOS side is done as well it can be merged.

Waiting for that. If you don't have experience with iOS/Obj-C I may look into it later.

Thank you.

[lucien-theron]

Okay thanks, I think its an Android specific issue but you are welcome to look into it. Reason for issue was highlighted here: https://github.com/transistorsoft/flutter_background_fetch/issues/22#issuecomment-481658481

[miguelpruivo]

Merged and published.

Thank you for contributing.