Xamarin-android: Conflicting libraries when using generated and packed Xamarin.Android Bindings.

[stugcearar]

Steps to Reproduce

1. Create a binding library of two different .aar library that each of them contains libs/r-classes.jar files in it.
2. Create nuget packages.
3. Adding nuget packages into Xamarin.Android demo project.
4. Build.

Expected Behavior

Build succssfully.

Actual Behavior

Below error occurred and break the build.

"JAR library references with identical file names but different contents were found: r-classes.jar. Please remove any conflicting libraries from EmbeddedJar, InputJar and AndroidJavaLibrary."

Version Information

Microsoft Visual Studio Community 2019
Version 16.8.4
VisualStudio.16.Release/16.8.4+30907.101
Microsoft .NET Framework
Version 4.7.03190

Installed Version: Community

Visual C++ 2019 00435-60000-00000-AA613
Microsoft Visual C++ 2019

ASP.NET and Web Tools 2019 16.8.557.25636
ASP.NET and Web Tools 2019

ASP.NET Core Razor Language Services 16.1.0.2052803+84e121f1403378489b842e1797df2f3f5a49ac3c
Provides languages services for ASP.NET Core Razor.

ASP.NET Web Frameworks and Tools 2012 16.8.557.25636
For additional information, visit https://www.asp.net/

ASP.NET Web Frameworks and Tools 2019 16.8.557.25636
For additional information, visit https://www.asp.net/

Azure App Service Tools v3.0.0 16.8.557.25636
Azure App Service Tools v3.0.0

Azure Functions and Web Jobs Tools 16.8.557.25636
Azure Functions and Web Jobs Tools

C# Tools 3.8.0-5.20604.10+9ed4b774d20940880de8df1ca8b07508aa01c8cd
C# components used in the IDE. Depending on your project type and settings, a different version of the compiler may be used.

Cake for Visual Studio 0.1.2.0
Adds support for the Cake build tool in Visual Studio 2017 and 2019. Includes support for the Task Runner Explorer, new templates and bootstrapping important Cake files.

Common Azure Tools 1.10
Provides common services for use by Azure Mobile Services and Microsoft Azure Tools.

Extensibility Message Bus 1.2.6 (master@34d6af2)
Provides common messaging-based MEF services for loosely coupled Visual Studio extension components communication and integration.

GitHub.VisualStudio 2.11.102.28613
A Visual Studio Extension that brings the GitHub Flow into Visual Studio.

IntelliCode Extension 1.0
IntelliCode Visual Studio Extension Detailed Info

Microsoft Azure Tools 2.9
Microsoft Azure Tools for Microsoft Visual Studio 2019 - v2.9.30924.1

Microsoft Continuous Delivery Tools for Visual Studio 0.4
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Microsoft JVM Debugger 1.0
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Microsoft Library Manager 2.1.113+g422d40002e.RR
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Microsoft MI-Based Debugger 1.0
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Microsoft Visual C++ Wizards 1.0
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Microsoft Visual Studio Tools for Containers 1.1
Develop, run, validate your ASP.NET Core applications in the target environment. F5 your application directly into a container with debugging, or CTRL + F5 to edit & refresh your app without having to rebuild the container.

Microsoft Visual Studio VC Package 1.0
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Mono Debugging for Visual Studio 16.8.43 (00471f8)
Support for debugging Mono processes with Visual Studio.

NuGet Package Manager 5.8.1
NuGet Package Manager in Visual Studio. For more information about NuGet, visit https://docs.nuget.org/

ProjectServicesPackage Extension 1.0
ProjectServicesPackage Visual Studio Extension Detailed Info

SQL Server Data Tools 16.0.62012.31170
Microsoft SQL Server Data Tools

Syntax Visualizer 1.0
An extension for visualizing Roslyn SyntaxTrees.

TypeScript Tools 16.0.21016.2001
TypeScript Tools for Microsoft Visual Studio

Visual Basic Tools 3.8.0-5.20604.10+9ed4b774d20940880de8df1ca8b07508aa01c8cd
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Visual F# Tools 16.8.0-beta.20507.4+da6be68280c89131cdba2045525b80890401defd
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Visual Studio Code Debug Adapter Host Package 1.0
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Visual Studio Container Tools Extensions 1.0
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Visual Studio Tools for Containers 1.0
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VisualStudio.DeviceLog 1.0
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VisualStudio.Foo 1.0
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VisualStudio.Mac 1.0
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Xamarin 16.8.000.261 (d16-8@bb99248)
Visual Studio extension to enable development for Xamarin.iOS and Xamarin.Android.

Xamarin Designer 16.8.0.507 (remotes/origin/d16-8@e87b24884)
Visual Studio extension to enable Xamarin Designer tools in Visual Studio.

Xamarin Templates 16.8.112 (86385a3)
Templates for building iOS, Android, and Windows apps with Xamarin and Xamarin.Forms.

Xamarin.Android SDK 11.1.0.26 (d16-8/a36ce73)
Xamarin.Android Reference Assemblies and MSBuild support.
Mono: 5e9cb6d
Java.Interop: xamarin/java.interop/d16-8@79d9533
ProGuard: Guardsquare/proguard/proguard6.2.2@ebe9000
SQLite: xamarin/sqlite/3.32.1@1a3276b
Xamarin.Android Tools: xamarin/xamarin-android-tools/d16-8@2fb1cbc

Xamarin.iOS and Xamarin.Mac SDK 14.8.0.3 (c51fabee8)
Xamarin.iOS and Xamarin.Mac Reference Assemblies and MSBuild support.

Log File

Not working because build phase is failed.

[grendello]

@stugcearar Please provide a verbose build log for the broken build. You can generate a binlog by building the project from the command line using the following command:

msbuild /bl

This will generate the msbuild.binlog file, please attach it here, thanks!

[jonathanpeppers]

I think the problem is step 1:

1. Create a binding library of two different .aar library that each of them contains libs/r-classes.jar files in it.

Is r-classes.jar a special name for a reason? Can they be named classes.jar as .aar files normally contain?

It seems only classes.jar is currently allowed:

https://github.com/xamarin/xamarin-android/blob/de5c8f89d18fcc8b39dd8e6ec1ccf51724dbadd0/src/Xamarin.Android.Build.Tasks/Tasks/CheckDuplicateJavaLibraries.cs#L29

We could also try removing this check completely, it seems like it was added because of:

The thing is, before this change things like ViewPagerIndicator in
monodroid-samples would be broken and users don't know why. It is because
android-support-v4.jar is now embedded in Mono.Android.Support.v4.dll and
its content is inconsistent with the jar which is explicitly added as
AndroidJavaLibrary for old style reference. Since their content are
different, they are regarded as different jars and thus conflict occurs.

https://github.com/xamarin/monodroid/commit/f53f25ecb3f8deaca84674beb592cb608953ec90

I don't think this is an issue anymore, Mono.Android.Support.v4.dll is long gone, because the Xamarin.Android.Support.* libraries are distributed from NuGet.

[stugcearar]

Yes, the problem occured in here:

<Target Name="_CheckDuplicateJavaLibraries" DependsOnTargets="_GetLibraryImports">
  <CheckDuplicateJavaLibraries
    JavaSourceFiles="@(AndroidJavaSource)"
    JavaLibraries="@(AndroidJavaLibrary)"
    LibraryProjectJars="@(ExtractedJarImports)" />
</Target>

But r-classes.jar is located in native android libraries. I did not add them. I can manage the build the application with the binding libraries but I changed the jar names manually. Shouldn't this be handled automatically by Xamarin.Android and not by the user?

[jonathanpeppers]

@stugcearar do you know why they are named r-classes.jar? Is this something Android Studio did by default?

[stugcearar]

I think the developers of the native library add resources like static strings in r-classes.jar. But they gave the same name this kind of classes in different .aar files. So when I used them together as nugets, the conflict happens on application project.

[jonathanpeppers]

@stugcearar can you attach the .aar files here? Or perhaps just the r-classes.jar?

[stugcearar]

@jonathanpeppers I created a sample .aar and binding library for the error and attached the zip file.
sample.zip

[jonathanpeppers]

@stugcearar how did you create the .aar files in your example, was it the project template in Android Studio?

I have a fix for the original error you were getting, but it seems incomplete: https://github.com/xamarin/xamarin-android/commit/55c29edbec2bacaafe7b460990117abbf45fedea

I get Unsupported class file major version 59, which I think is because the r-classes.jar files are Java 14.

[jonathanpeppers]

Wait, or is this somehow Java 15?

https://stackoverflow.com/questions/9170832/list-of-java-class-file-format-major-version-numbers

I don't see how Java 15 would work on Android, how did you create the .aar files?

[stugcearar]

Yes I used Android Studio template for .aar files but I think maybe cause of the error is .jar files. I created them with jar and r-classes.jar with javac commands with CLI. I can create them again if you like?

[jonathanpeppers]

Ok that makes sense, thanks.

I’ll make new ones for this test, no worries.