运行从 Github checkout 的开源 Flutter 应用程序时出现以下错误。它运行屏幕的第一个 Activity 并在大约 1 秒后应用程序崩溃并在 Logcat 中出现以下错误。我在 Flutter 的运行控制台中看不到任何错误。
Process: app.ceylon.selftrackingapp, PID: 32590
java.lang.RuntimeException: Unable to start activity ComponentInfo{app.ceylon.selftrackingapp/app.ceylon.selftrackingapp.MainActivity}: java.lang.NullPointerException: Attempt to invoke interface method 'void io.flutter.plugin.common.BinaryMessenger.setMessageHandler(java.lang.String, io.flutter.plugin.common.BinaryMessenger$BinaryMessageHandler)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3448)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3595)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2147)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:237)
at android.app.ActivityThread.main(ActivityThread.java:7811)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1076)
Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'void io.flutter.plugin.common.BinaryMessenger.setMessageHandler(java.lang.String, io.flutter.plugin.common.BinaryMessenger$BinaryMessageHandler)' on a null object reference
at io.flutter.plugin.common.MethodChannel.setMethodCallHandler(MethodChannel.java:116)
at com.baseflow.geolocator.GeolocatorPlugin.registerWith(GeolocatorPlugin.java:49)
at io.flutter.plugins.GeneratedPluginRegistrant.registerWith(GeneratedPluginRegistrant.java:20)
at app.ceylon.selftrackingapp.MainActivity.onCreate(MainActivity.kt:32)
at android.app.Activity.performCreate(Activity.java:7955)
at android.app.Activity.performCreate(Activity.java:7944)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1307)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3423)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3595)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2147)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:237)
at android.app.ActivityThread.main(ActivityThread.java:7811)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1076)
2020-03-21 10:09:53.328 15534-15539/? E/nightwatch-watcher: Failed to read from logcat: Success
我正在使用实际设备 Galaxy S9+ 进行测试，这是我安装在计算机中的 Flutter 版本。
Flutter 1.15.17 • channel beta • https://github.com/flutter/flutter.git
Framework • revision 2294d75bfa (2 weeks ago) • 2020-03-07 00:28:38 +0900
Engine • revision 5aff311948
Tools • Dart 2.8.0 (build 2.8.0-dev.12.0 9983424a3c)
最佳答案
我也在寻找解决方案，我找到了一个 here .
核心是:在pubspec.yaml中添加“flutter_plugin_android_lifecycle:^1.0.4”
关于android - 运行 Flutter App 时出现 java.lang.NullPointerException，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/60784577/