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Switch JniEnvironment.FindClass to use Class.forName instead of ClassLoader.loadClass #23

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garuma opened this issue Apr 11, 2016 · 0 comments
Open

Switch JniEnvironment.FindClass to use Class.forName instead of ClassLoader.loadClass #23

garuma opened this issue Apr 11, 2016 · 0 comments
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enhancement Proposed change to current functionality java-interop Runtime bridge between .NET and Java

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@garuma
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garuma commented Apr 11, 2016

See equivalent commit in monodroid: https://github.com/xamarin/monodroid/commit/ed984a3a0bfbe71f6499a7855c647b5bc2b28466
@jpobst jpobst added enhancement Proposed change to current functionality java-interop Runtime bridge between .NET and Java labels Apr 16, 2020
@jonathanpeppers jonathanpeppers mentioned this issue Feb 7, 2025
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jonpryor pushed a commit to dotnet/android that referenced this issue Feb 8, 2025
@jonathanpeppers
[Mono.Android] JNIEnv.FindClass() uses `JniEnvironment.Types.FindCl…
aba2726 
…ass()` (#9769)

Context: xamarin/monodroid@ed984a3
Context: dotnet/java-interop#23

Update `JNIEnv.FindClass()` to use `JniEnvironment.Types.FindClass()`.

This avoids the problem of `JNIEnvInit.mid_Class_forName` being
`null` in a NativeAOT context:

	E AndroidRuntime: Process: net.dot.hellonativeaot, PID: 30744
	E AndroidRuntime: net.dot.jni.internal.JavaProxyThrowable: System.TypeInitializationException: TypeInitialization_Type_NoTypeAvailable
	E AndroidRuntime:  ---> System.ArgumentNullException: ArgumentNull_Generic Arg_ParamName_Name, method
	E AndroidRuntime:    at Java.Interop.JniEnvironment.StaticMethods.CallStaticObjectMethod(JniObjectReference, JniMethodInfo, JniArgumentValue*) + 0x1c8
	E AndroidRuntime:    at Android.Runtime.JNIEnv.FindClass(String) + 0xb4
	E AndroidRuntime:    at Java.Lang.Class..cctor() + 0x7c
	E AndroidRuntime:    at System.Runtime.CompilerServices.ClassConstructorRunner.EnsureClassConstructorRun(StaticClassConstructionContext*) + 0xb4
	E AndroidRuntime:    Exception_EndOfInnerExceptionStack
	E AndroidRuntime:    at System.Runtime.CompilerServices.ClassConstructorRunner.EnsureClassConstructorRun(StaticClassConstructionContext*) + 0x160
	E AndroidRuntime:    at System.Runtime.CompilerServices.ClassConstructorRunner.CheckStaticClassConstructionReturnNonGCStaticBase(StaticClassConstructionContext*, IntPtr) + 0x14
	E AndroidRuntime:    at Android.Runtime.JNIEnv.FindClass(String) + 0xc0
	E AndroidRuntime:    at Android.App.Application.get_Context() + 0x50
	E AndroidRuntime:    at Microsoft.Maui.Hosting.EssentialsExtensions.<>c.<UseEssentials>b__0_0(ILifecycleBuilder life) + 0x18
	E AndroidRuntime:    at Microsoft.Maui.LifecycleEvents.LifecycleEventService..ctor(IEnumerable`1) + 0x94
	E AndroidRuntime:    at Microsoft.Maui.LifecycleEvents.MauiAppHostBuilderExtensions.<>c.<ConfigureLifecycleEvents>b__0_0(IServiceProvider sp) + 0x3c
	E AndroidRuntime:    at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitRootCache(ServiceCallSite, RuntimeResolverContext) + 0x68
	E AndroidRuntime:    at Microsoft.Extensions.DependencyInjection.ServiceProvider.CreateServiceAccessor(ServiceIdentifier serviceIdentifier) + 0x180
	E AndroidRuntime:    at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey, Func`2) + 0x11c
	E AndroidRuntime:    at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(ServiceIdentifier, ServiceProviderEngineScope) + 0x44
	E AndroidRuntime:    at Microsoft.Maui.MauiContext.WrappedServiceProvider.GetService(Type) + 0x48
	E AndroidRuntime:    at Microsoft.Maui.MauiContext.WrappedServiceProvider.GetService(Type) + 0x48
	E AndroidRuntime:    at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetService[T](IServiceProvider) + 0x3c
	E AndroidRuntime:    at Microsoft.Maui.LifecycleEvents.LifecycleEventServiceExtensions.<GetLifecycleEventDelegates>d__3`1.MoveNext() + 0x38
	E AndroidRuntime:    at Microsoft.Maui.LifecycleEvents.LifecycleEventServiceExtensions.InvokeLifecycleEvents[TDelegate](IServiceProvider, Action`1) + 0x68
	E AndroidRuntime:    at Microsoft.Maui.MauiApplication.OnCreate() + 0xb0
	E AndroidRuntime:    at Android.App.Application.n_OnCreate(IntPtr jnienv, IntPtr native__this) + 0xb0
	E AndroidRuntime: at my.MainApplication.n_onCreate(Native Method)
	E AndroidRuntime: at my.MainApplication.onCreate(MainApplication.java:24)
	E AndroidRuntime: at android.app.Instrumentation.callApplicationOnCreate(Instrumentation.java:1386)
	E AndroidRuntime: at android.app.ActivityThread.handleBindApplication(ActivityThread.java:7398)
	E AndroidRuntime: at android.app.ActivityThread.-$$Nest$mhandleBindApplication(Unknown Source:0)
	E AndroidRuntime: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2379)
	E AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:107)
	E AndroidRuntime: at android.os.Looper.loopOnce(Looper.java:232)
	E AndroidRuntime: at android.os.Looper.loop(Looper.java:317)
	E AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:8592)
	E AndroidRuntime: at java.lang.reflect.Method.invoke(Native Method)
	E AndroidRuntime: at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:580)
	E AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:878)

This also allows us to remove these fields that are now unused:

  * `JnienvInitializeArgs.Class_forName`
  * `JNIEnv.BinaryName()`

TODO?  While `JNIEnv.FindClass()` was using [`Class.forName()`][0],
`JniEnvironment.Types.FindClass()` uses [`ClassLoader.loadClass()`][1].
`JNIEnv.FindClass()` originally used `ClassLoader.loadClass()`, but
was changed to use `Class.forName()` in xamarin/monodroid@ed984a3a as
part of supporting the Xamarin.Android Designer.

Updating `JNIEnv.FindClass()` to use `JniEnvironment.Types.FindClass()`
effectively reverts that original change.  This is "fine" for now --
the Xamarin.Android Designer is no longer supported -- but in the
future we may want to update `JniEnvironment.Types.FindClass()` to
use `Class.forName()`; see dotnet/java-interop#23.

[0]: https://developer.android.com/reference/java/lang/Class#forName(java.lang.String)
[1]: https://developer.android.com/reference/java/lang/ClassLoader#loadClass(java.lang.String)
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@garuma @jpobst