[Add2App][Android][Crash] FlutterFragment crash by activity / fragment recycled #110138
Description
Our App got a lot of crashes while doing flutter migration. The stack trace as below
Caused by java.lang.NullPointerException
Attempt to invoke virtual method 'void io.flutter.embedding.android.m.e()' on a null object reference
===========================================
io.flutter.embedding.android.FlutterActivityAndFragmentDelegate.onDestroyView (FlutterActivityAndFragmentDelegate.java:613)
io.flutter.embedding.android.FlutterFragment.detachFromFlutterEngine (FlutterFragment.java:869)
io.flutter.embedding.android.FlutterActivityAndFragmentDelegate.detachFromFlutterEngine (FlutterActivityAndFragmentDelegate.java:649)
io.flutter.embedding.engine.FlutterEngineConnectionRegistry.attachToActivity (FlutterEngineConnectionRegistry.java:319)
io.flutter.embedding.android.FlutterActivityAndFragmentDelegate.onAttach (FlutterActivityAndFragmentDelegate.java:189)
Steps to Reproduce
- clone code sample from crash_demo
- before run demo, turn on
Don't keep activitiesin android settings > system > developer options > apps - run app, fast switch apps by swiping system navigation bar
(you could follow the steps as demo video shown)
Expected results:
App could restore without any error.
Actual results:
App crash randomly while restoring activity with flutter fragment.
Code sample
override fun onCreate(savedInstanceState: Bundle?) {
engineBindings.attach()
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
flutterFragment =
FlutterFragment.withCachedEngine("shared_engine").renderMode(RenderMode.texture).build()
val transaction = supportFragmentManager.beginTransaction()
transaction.add(R.id.container, flutterFragment!!, "Flutter_Page")
transaction.commit()
}
override fun onDestroy() {
super.onDestroy()
engineBindings.detach()
}and implement event handler from the tutorial Adding a Flutter Fragment to an Android app
Logs
FATAL EXCEPTION: main
Process: dev.flutter.multipleflutters, PID: 24902
java.lang.RuntimeException: Unable to start activity ComponentInfo{dev.flutter.multipleflutters/dev.flutter.multipleflutters.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void io.flutter.embedding.android.FlutterView.detachFromFlutterEngine()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3635)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3792)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:103)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2210)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loopOnce(Looper.java:201)
at android.os.Looper.loop(Looper.java:288)
at android.app.ActivityThread.main(ActivityThread.java:7839)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void io.flutter.embedding.android.FlutterView.detachFromFlutterEngine()' on a null object reference
at io.flutter.embedding.android.FlutterActivityAndFragmentDelegate.onDestroyView(FlutterActivityAndFragmentDelegate.java:613)
at io.flutter.embedding.android.FlutterFragment.detachFromFlutterEngine(FlutterFragment.java:869)
at io.flutter.embedding.android.FlutterActivityAndFragmentDelegate.detachFromFlutterEngine(FlutterActivityAndFragmentDelegate.java:649)
at io.flutter.embedding.engine.FlutterEngineConnectionRegistry.attachToActivity(FlutterEngineConnectionRegistry.java:319)
at io.flutter.embedding.android.FlutterActivityAndFragmentDelegate.onAttach(FlutterActivityAndFragmentDelegate.java:189)
at io.flutter.embedding.android.FlutterFragment.onAttach(FlutterFragment.java:777)
at androidx.fragment.app.Fragment.performAttach(Fragment.java:2574)
at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:828)
at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManagerImpl.java:1238)
at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:1303)
at androidx.fragment.app.FragmentManagerImpl.dispatchStateChange(FragmentManagerImpl.java:2659)
at androidx.fragment.app.FragmentManagerImpl.dispatchCreate(FragmentManagerImpl.java:2607)
at androidx.fragment.app.FragmentController.dispatchCreate(FragmentController.java:235)
at androidx.fragment.app.FragmentActivity.onCreate(FragmentActivity.java:316)
at androidx.appcompat.app.AppCompatActivity.onCreate(AppCompatActivity.java:106)
at dev.flutter.multipleflutters.MainActivity.onCreate(MainActivity.kt:24)
at android.app.Activity.performCreate(Activity.java:8050)
at android.app.Activity.performCreate(Activity.java:8030)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1329)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3608)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3792)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:103)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2210)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loopOnce(Looper.java:201)
at android.os.Looper.loop(Looper.java:288)
at android.app.ActivityThread.main(ActivityThread.java:7839)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003)
[✓] Flutter (Channel stable, 3.0.5, on macOS 12.2.1 21D62 darwin-arm, locale zh-Hant-TW)
• Flutter version 3.0.5 at /Users/bradchien/development/flutter
• Upstream repository https://github.com/flutter/flutter.git
• Framework revision f1875d570e (6 weeks ago), 2022-07-13 11:24:16 -0700
• Engine revision e85ea0e79c
• Dart version 2.17.6
• DevTools version 2.12.2
[✓] Android toolchain - develop for Android devices (Android SDK version 32.1.0-rc1)
• Android SDK at /Users/bradchien/Library/Android/sdk
• Platform android-32, build-tools 32.1.0-rc1
• Java binary at: /Applications/Android Studio Preview.app/Contents/jre/jdk/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build 11.0.13+0-b1751.21-8125866)
• All Android licenses accepted.
[✓] Xcode - develop for iOS and macOS (Xcode 13.4.1)
• Xcode at /Applications/Xcode.app/Contents/Developer
• CocoaPods version 1.11.3
[✓] Chrome - develop for the web
• Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome
[✓] Android Studio
• Android Studio at /Applications/Android Studio Preview.app/Contents
• Flutter plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/9212-flutter
• Dart plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/6351-dart
• Java version OpenJDK Runtime Environment (build 11.0.13+0-b1751.21-8125866)
[✓] Connected device (4 available)
• Pixel 6 (mobile) • 1A021FDF6008KX • android-arm64 • Android 12 (API 31)
• KKTV iPhone 11 Pro (mobile) • 00008030-001139100E00802E • ios • iOS 15.6 19G71
• macOS (desktop) • macos • darwin-arm64 • macOS 12.2.1 21D62 darwin-arm
• Chrome (web) • chrome • web-javascript • Google Chrome 104.0.5112.101
! Error: 遙遠的TV is not connected. Xcode will continue when 遙遠的TV is connected. (code -13)
[✓] HTTP Host Availability
• All required HTTP hosts are available