Gradle and multiple projects with Roboguice dependency

Question

I'm trying to migrate an old IntelliJ project to use gradle. However, assembleDebug fails during the dx step:

java.lang.IllegalArgumentException: already added: Lcom/google/inject/AbstractModule;
    at com.android.dx.dex.file.ClassDefsSection.add(ClassDefsSection.java:123)
    at com.android.dx.dex.file.DexFile.add(DexFile.java:163)
    at com.android.dx.command.dexer.Main.processClass(Main.java:490)
    at com.android.dx.command.dexer.Main.processFileBytes(Main.java:459)
    at com.android.dx.command.dexer.Main.access$400(Main.java:67)
    at com.android.dx.command.dexer.Main$1.processFileBytes(Main.java:398)
    at com.android.dx.cf.direct.ClassPathOpener.processArchive(ClassPathOpener.java:245)
    at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:131)
    at com.android.dx.cf.direct.ClassPathOpener.process(ClassPathOpener.java:109)
    at com.android.dx.command.dexer.Main.processOne(Main.java:422)
    at com.android.dx.command.dexer.Main.processAllFiles(Main.java:333)
    at com.android.dx.command.dexer.Main.run(Main.java:209)
    at com.android.dx.command.dexer.Main.main(Main.java:174)
    at com.android.dx.command.Main.main(Main.java:91)

My project is split into two subprojects: a main project and a library project. Both these project have Roboguice and Guice as dependencies.

I tried Xav's suggested workaround for including the support library in multiple projects as mentioned in this answer. The workaround should probably not even be necessary, given that roboguice/guice are both picked up from maven central. I created a dummy library project that's the only project that depends on roboguice/guice. I made it so that my main project and the (true) library project both depend on this dummy project. However, I get the same error.

How can this be fixed?

settings.gradle in the root directory:

include 'MainApp'
include 'library'
include 'common-library'

build.gradle in the root directory:

buildscript {
  repositories {
      mavenCentral()
  }
  dependencies {
      classpath 'com.android.tools.build:gradle:0.4.2'
  }
}

allprojects {
    version = '1.0'

    repositories {
        mavenCentral()
    }
}

apply plugin: 'android-reporting'

build.gradle in the main project and the real library project:

apply plugin: 'android'

android {
    compileSdkVersion 15
    buildToolsVersion "17.0"
    sourceSets         {
      main {
           manifest.srcFile 'AndroidManifest.xml'
           java.srcDirs = ['src']
           res.srcDirs = ['res']
      }
    }
}

dependencies {
    compile project(':library') // only in main, not in real library
    compile project(':common-library')
}

build.gradle in the dummy library project:

apply plugin: 'android-library'

android {
    compileSdkVersion 15
    buildToolsVersion "17.0"
    sourceSets         {
      main {
           manifest.srcFile 'AndroidManifest.xml'
           java.srcDirs = ['src']
           res.srcDirs = ['res']
      }
    }
}

dependencies {
  compile 'org.roboguice:roboguice:2.0'
  compile 'com.google.inject:guice:3.0'
}

Answer 1

You're right that the dummy library isn't necessary since you're using Maven. If you look at the .pom for Roboguice, it lists Guice as a dependency with the "no_aop" classifier. However, you're also listing Guice explicitly without the classifier. My guess is that Maven is pulling in both versions, which results in the dexing merge conflict.

Try removing compile 'com.google.inject:guice:3.0' from your Gradle build file and see if it builds.