Bind library that uses Java 8+ API desugaring support

[4brunu]

Hi,

I'm not sure if here is the right place to ask, but is it possible to bind a native android library (.aar), that uses Java 8+ API desugaring support?

https://developer.android.com/studio/write/java8-support

A library that uses for example import java.time.*

This is how the support for Java 8+ API desugaring is enabled in Android Studio.

android {
  defaultConfig {
    // Required when setting minSdkVersion to 20 or lower
    multiDexEnabled true
  }

  compileOptions {
    // Flag to enable support for the new language APIs
    coreLibraryDesugaringEnabled true
    // Sets Java compatibility to Java 8
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
  }
}

dependencies {
  coreLibraryDesugaring 'com.android.tools:desugar_jdk_libs:1.1.1'
}

Is there something like this for Xamarin?
Is it possible to bind a native android library (.aar) that was created with this configuration?
Because I couldn't find a nuget package equivalent to 'com.android.tools:desugar_jdk_libs:1.1.1'.

Thanks

[pjcollins]

I think this should "just work" following these instructions: https://docs.microsoft.com/en-us/xamarin/android/platform/binding-java-library/binding-an-aar. I don't believe you need to worry about adding any desugaring support library. Looping in @jonathanpeppers and @jpobst to maybe help provide more context if needed.

[4brunu]

In Android Studio, If I create a library that uses import java.time.* with the previous configurations, and then consume this aar in an app in Android Studio, I also need to add those previous configurations, otherwise, it will crash the app.

[jonathanpeppers]

As long as the Xamarin.Android application project is using d8/r8, things should work by default and you don't need to do anything.

More information on this here:

https://github.com/xamarin/xamarin-android/blob/master/Documentation/guides/D8andR8.md#what-does-this-process-look-like-with-d8--r8-enabled

If you are wanting to build a NuGet package, you might consider including an MSBuild .targets file that requires <AndroidDexTool>d8</AndroidDexTool> to be set. It likely won't work to use dx.

I would try it in a "hello world" Xamarin.Android project, and let us know how far you get, thanks!

[4brunu]

Hi,

As @jonathanpeppers suggested, I created a "hello world" Xamarin.Android project and did a bind of a aar that uses Java 8+ API desugaring, and import java.time.*.

I enabled d8/r8, but got the following crash.

Java.Lang.NoClassDefFoundError has been thrown
Failed resolution of: Ljava/time/LocalDateTime

Then I added the jar 'com.android.tools:desugar_jdk_libs:1.1.1' to the project, and it worked.

I got the same results with Xamarin and with Android Studio, when bind the aar that uses Java 8+ API desugaring, and import java.time.*.

So I opened dotnet/android-libraries#245 to fix this issue.

[4brunu]

Here is the code I used in the sample library

package com.example.mylibrary

import java.time.LocalDateTime

object Time {
    @JvmStatic
    fun whatTimeIsIt(): String {
        return LocalDateTime.now().toString()
    }
}

[jonathanpeppers]

Did you get this error at build time? or when running the app?

Java.Lang.NoClassDefFoundError has been thrown
Failed resolution of: Ljava/time/LocalDateTime

Can you attach the project here if it is a sample?

[4brunu]

It's a runtime error, when running the app on Android API 23 or bellow.
Because import java.time.* was only included in Android platform on API 24 and above.

Here is a sample project in attach.

The sample project has the native Android Library in the directory NativeApplicationWithNativeLib.
Then you have the directory MyApp2 that have the Xamaron Android app, and the MyLib, which is the bind for the native Android Library in the directory NativeApplicationWithNativeLib

The project now works on Android API 23 or bellow as well as API 24 and above.

If you remove the file SampleJava8/MyApp2/MyLib/Jars/desugar_jdk_libs-1.1.1.jar, it will only work on API 24 and above.

SampleJava8.zip

[Da-Kling]

Hi,

I got a similar problem. I am using a third-party library which uses JAVA8+ API and got runtime errors running on Android 23.

Java.Lang.NoSuchMethodError: 'No interface method stream()Ljava/util/stream/Stream; in class Ljava/util/Queue; or its super classes (declaration of 'java.util.Queue' appears in /system/framework/core-libart.jar)'

Even including the desugar_jdk_libs-1.1.1.jar as proposed in the example results in the same error.

Any suggestions?

[4brunu]

Since xamarin/XamarinComponents#1180 got merged, I think this can now be closed.