Lambda causes compiler exception in Android Library Module

Question

When I use a lambda expression in an Android Library Module, I receive a compiler exception com.sun.tools.javac.code.Symbol$CompletionFailure: class file for java.lang.invoke.MethodType not found.

Lambda expressions are compiling without error when used in the Android application module.

A sample project to demonstrate the problem can be found here:
https://github.com/adamdye/AndroidLambdaIssue

The interesting classes in the example are MyLibrary.java and MainActivity.java. Each class contains the identical expressions.

Setup

 Android Studio 2.2 preview 1
 min/target SDK version = android-N
 build tools version = 24.0.0.rc4
jack compiler enabled
source/target compatibility = 1.8
Gradle version = 2.10
Android Plugin Version = 2.2.0-alpha1
JDK = java 8 

I am not interested in using retro-lambda. I'd like to get this working through proper configuration. I assume I'm missing a step somewhere.

Answer 1

Just to circle back, and add what I've learned.

I was able to get past the MethodType not found error by adding my JAVA HOME's runtime jar to gradle's bootclasspath in the project's build.gradle file.

allprojects {    
    gradle.projectsEvaluated {
        tasks.withType(JavaCompile) {
            options.compilerArgs << "-Xbootclasspath/a:" + System.properties.get("java.home") + "/lib/rt.jar"
        }
    }
}

However, the app would not deploy to a device or emulator because the app:transformClassesWithPreJackPackagedLibrariesForDebug gradle task fails. It requires that all interfaces that are used as a lamba are on the classpath. The bootclasspath fix did not set the classpath for the Jack compiler and libraries do not use the Jack compiler yet.

I opened a bug report on this issue: https://code.google.com/p/android/issues/detail?id=211386

They commented that this will be addressed in the near future.

Answer 2

I solved the problem by including the JAR containing Java sources as a dependency, instead of the compiled JAR. This is how I configured my projects:

In library's build.gradle:

configurations {
    sources
}

task sourcesJar(type: Jar, dependsOn: classes) {
    classifier = 'sources'
    from sourceSets.main.java.srcDirs
}

artifacts {
    sources sourcesJar
}

In app's build.gradle:

dependencies {
    compile project(path: ":gdxstudio-core", configuration: "sources")

Of course the library is included as an external project in app's settings.gradle