'NoSuchMethodError' calling static interface method on pre-API-24

[vas1l3nk]

Android application type

Classic Xamarin.Android (MonoAndroid12.0, etc.)

Affected platform version

VSMac 8.10.19(build 2)

Description

The problem occurs when I try to call an initialisation native method from my binding library (.aar). I know that the method exist in my Android Binding Library. Deleting folders bin and obj and rebuilding the project does not help. I also watched the file api.xml this method is there, and and I can refer to it. Removing or adding a method to Metadata.xml also doesn't help.
I also decompiled the .dll file and saw this method there.

method: Start(global::Android.Content.Context context, global::package.name.Configuration configuration)
The error I'm getting

Java.Lang.NoSuchMethodError
no static method "Lpackage/name/SDK;.start(Landroid/content/Context;Lpackage/name/Configuration;)V"

Steps to Reproduce

Create Android Binding library via .arr, which needs to be initialized in MyApplication.cs
Add reference from the Xamarin.Android project to Binding library.
Start the app

Did you find any workaround?

No response

Relevant log output

No response

[jpobst]

This error means the Java compiled method cannot be found. There are a few possible cases to investigate:

• The classes.jar from the .aar is not being included in the binding library. Make sure your build action is set to LibraryProjectZip. This will add the .aar as an embedded resource in your binding librarly .dll.
• The Java linker is removing the method. You will need to investigate Proguard rules if your method is getting removed from the Java .jar.

You probably don't want to mess with the Metadata for this case. Using the automatically generated one should create the correct mapping to the Java class.

[vas1l3nk]

I added proguard rules to the native library, but nothing has changed.
I added proguard rules to the binding project and xamarin.android app but still nothing changed.

[vas1l3nk]

after adding proguard rules, I got this error

Java.Lang.IncompatibleClassChangeError
no static method "Lpackage/name/SDK;.start(Landroid/content/Context;Lpackage/name/Configuration;)V"

[vas1l3nk]

Hi @jpobst, I found such a thing.

the fact is that when initializing my library, one of the parameters is the context.
I tried adding <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
it, but nothing changes either. could this be the cause of the error?

and one more thing I noticed.

the native method takes android.content.context as one of the arguments. on the xamarin app side, I pass this:

Android.Content.Context context = Android.App.Application.Context;
Method.Start(context, myConfiguration);

And before calling this method in "Application output", I get Attempt to remove non-JNI local reference, dumping thread

[jpobst]

Can you post:

• The Java source code of the method you are trying to bind. (You can omit the method body)
• The C# binding code that gets generated for the method.

[vas1l3nk]

@jpobst Thanks for a quick reply.
Everything I have on the Java side
@kotlin.jvm.JvmStatic public final fun start(context: android.content.Context, configuration: package.name.Configuration): kotlin.Unit { /* compiled code */ }

C# code

Metadata.xml XPath method reference: path="/api/package[@name='package.name']/interface[@name='Interface']/method[@name='start' and count(parameter)=2 and parameter[1][@type='android.content.Context'] and parameter[2][@type='package.name.Configuration']]"
		[Register ("start", "(Landroid/content/Context;Lpackage/name/Configuration;)V", "")]
		public static unsafe void Start (global::Android.Content.Context context, global::package.name.Configuration configuration)
		{
			const string __id = "start.(Landroid/content/Context;Lpackage/name/Configuration;)V";
			try {
				JniArgumentValue* __args = stackalloc JniArgumentValue [2];
				__args [0] = new JniArgumentValue ((context == null) ? IntPtr.Zero : ((global::Java.Lang.Object) context).Handle);
				__args [1] = new JniArgumentValue ((configuration == null) ? IntPtr.Zero : ((global::Java.Lang.Object) configuration).Handle);
				_members.StaticMethods.InvokeVoidMethod (__id, __args);
			} finally {
				global::System.GC.KeepAlive (context);
				global::System.GC.KeepAlive (configuration);
			}
		}

		static readonly JniPeerMembers _members = new XAPeerMembers ("package/name/Class", typeof (Class));

[jpobst]

Hmm, since the original code is Kotlin, and it's monkeying with how it will actually look in Java, let's see how it looks in Java.

Use a Java decompiler on your .jar file and post how the method actually got compiled into Java. (I use http://java-decompiler.github.io if you don't already have a Java decompiler.)

Additionally, this looks like a static method on an interface, which traditionally isn't supported in C#.

You can try enabling <_EnableInterfaceMembers> if you want to support the static method on the C# interface: https://docs.microsoft.com/en-us/xamarin/android/release-notes/10/10.1#c-80-default-interface-members-for-bindings-projects.

Alternatively, it looks like this is handled the old way where it has been moved to a class instead.

Please post the C# class signature (including the [Register] attribute) for the C# type containing the Start method.

[vas1l3nk]

@jpobst Thanks for reply. This is from java decompiler

@Metadata(mv = {1, 6, 0}, k = 1, xi = 48, d1 = {"\000\f\n\002\030\002\n\002\020\000\n\002\b\b\bf\030\000 \0032\0020\001:\007\002\003\004\005\006\007\b\006\t"}, d2 = {"Lpackage/name/Name;", "", "sdk_release"})
public interface Name {
  @NotNull
  public static final Companion Companion = Companion.$$INSTANCE;
  
  @JvmStatic
  static void start(@NotNull Context context, @NotNull Configuration configuration) {
    Companion.start(context, configuration);
  }
  

C# signarure with [Register]:

// Metadata.xml XPath interface reference: path="/api/package[@name='package.name']/interface[@name='Name']"
	[Register ("package/name/Name", "", "Package.Name.INameInvoker")]
	public partial interface IName : IJavaObject, IJavaPeerable {
		private static readonly JniPeerMembers _members = new XAPeerMembers ("package/name/Name", typeof (IName), isInterface: true);


		// Metadata.xml XPath field reference: path="/api/package[@name='package.name']/interface[@name='Name']/field[@name='Companion']"
		[Register ("Companion")]
		public static global::Package.Name.NameCompanion Companion {
			get {
				const string __id = "Companion.Lpackage/name/Name$Companion;";

				var __v = _members.StaticFields.GetObjectValue (__id);
				return global::Java.Lang.Object.GetObject<global::Package.Name.NameCompanion> (__v.Handle, JniHandleOwnership.TransferLocalRef);
			}
		}

		// Metadata.xml XPath method reference: path="/api/package[@name='package.name']/interface[@name='Name']/method[@name='start' and count(parameter)=2 and parameter[1][@type='android.content.Context'] and parameter[2][@type='package.name.Name.Configuration']]"
		[Register ("start", "(Landroid/content/Context;Lpackage/name/Name$Configuration;)V", "")]
		public static unsafe void Start (global::Android.Content.Context context, global::Package.Name.NameConfiguration configuration)
		{
			const string __id = "start.(Landroid/content/Context;Lpackage/name/Name$Configuration;)V";
			try {
				JniArgumentValue* __args = stackalloc JniArgumentValue [2];
				__args [0] = new JniArgumentValue ((context == null) ? IntPtr.Zero : ((global::Java.Lang.Object) context).Handle);
				__args [1] = new JniArgumentValue ((configuration == null) ? IntPtr.Zero : ((global::Java.Lang.Object) configuration).Handle);
				_members.StaticMethods.InvokeVoidMethod (__id, __args);
			} finally {
				global::System.GC.KeepAlive (context);
				global::System.GC.KeepAlive (configuration);
			}
		}

	}

I have already tried to add :

<PropertyGroup>
  <LangVersion>preview</LangVersion>
  <_EnableInterfaceMembers>true</_EnableInterfaceMembers>
</PropertyGroup>

but nothing has changed

[vas1l3nk]

at first there was a class, but after restarting the mac and rebuild, the interface appeared lol

[jpobst]

Is this still the exact error message you are getting?

Java.Lang.NoSuchMethodError
no static method "Lpackage/name/SDK;.start(Landroid/content/Context;Lpackage/name/Configuration;)V"

I would expect Lpackage/name/Name;...... There is no type called SDK that I see.

The other thing to check would be to decompile your C# binding assembly and see if it contains the compiled .jar as an embedded resource. The compiled Java code has to make it on to the device as well as the compiled C# code for it to work.

[vas1l3nk]

@jpobst Thanks for a qiuck reply. Yes, it's still the same error, SDK and Name are not the real names of packages and interfaces. I'm sorry if this has caused you any inconvenience.

This is from AndroidLibraryProjects.zip and the same I see in classes.jar:

@Metadata(mv = {1, 6, 0}, k = 1, xi = 48, d1 = {"\000\f\n\002\030\002\n\002\020\000\n\002\b\t\bf\030\000 \0042\0020\001:\b\002\003\004\005\006\007\b\t\006\n"}, d2 = {"Lpackage/name/Name;", "", "sdk_release"})
public interface Name {
  @NotNull
  public static final Companion Companion = Companion.$$INSTANCE;
  
  @JvmStatic
  static void start(@NotNull Context context, @NotNull Configuration configuration) {
    Companion.start(context, configuration);
  }

or did I misunderstand you?

And my build action is set to LibraryProjectZip in my .aar file