External Android library projects with Gradle

Question

I am trying to build an Android project with Gradle and the Android Gradle plugin . I would like to depend on library projects found in external (maven) repositories, eg ActionBarSherlock.

This seems possible according to the official site :

Using a library is done one of the following way:

Multi-project setup. Read here: http://www.gradle.org/docs/current/userguide/multi_project_builds.html

Dependencies through a repo such as maven or ivy.

The current contents of my build.gradle:

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:0.2'
    }
}
apply plugin: 'android'

repositories {
    mavenCentral()
}

dependencies {
    compile 'com.actionbarsherlock:library:4.2.0'
}

android {
    target = 'android-16'
    sourceSets {
        main {
            manifest {
                srcFile 'AndroidManifest.xml'
            }
            java {
                srcDir 'src'
            }
            res {
                srcDir 'res'
            }
            assets {
                srcDir 'assets'
            }
            resources {
                srcDir 'src'
            }
        }
    }
}

I am using Gradle 1.2. When I try to build with gradle assemble , I get the following error:

Error: duplicate files during packaging of APK /[path to project]/build/apk/[project name]-debug-unaligned.apk
    Path in archive: AndroidManifest.xml
    Origin 1: /[path to project]/build/libs/[apk name]-debug.ap_
    Origin 2: /[home directory]/.gradle/caches/artifacts-14/filestore/com.actionbarsherlock/actionbarsherlock/4.2.0/apklib/dd63451a922558005d8c10be1085b488ed731d19/actionbarsherlock-4.2.0.apklib
:packageDebug FAILED

It seems like it is trying to include the AndroidManifest.xml from both the library project and my project. If I remove the manifest specification in sourceSets , I still get the same error.

The site mentions using apply plugin: 'android-library' for library projects; I am guessing this is only when building the actual library (with a multi-project setup) since doing so does not produce an APK.

How can I get external Android library project dependencies to work?

Answer 1

While it is possible to get dependencies through a Maven or Ivy repository, those are not packaged in a standard Jar archive. There is a new format designed specifically for this build system. The type is 'aar'

Current Android Libraries available on Maven Central were created using the Maven plugin which use a different archive format ('apklib') so they are not compatible.

If you look at com.actionbarsherlock:actionbacksherlock (which is the new location of that library), you'll see its format is apklib. http://search.maven.org/#artifactdetails%7Ccom.actionbarsherlock%7Cactionbarsherlock%7C4.2.0%7Capklib

Looking at the source code, we check for 'aar' packaging and revert to processing all others as 'jar' which is obviously a problem here. We should detect apklib and provide a better error message.

Answer 2

You can integrate the ActionBarSherlock as an aar now.

Just add this to your dependency definition in your build.gradle file:

dependencies {
    compile 'com.android.support:support-v4:18.0.+'
    compile 'com.actionbarsherlock:actionbarsherlock:4.4.0@aar'

Jake Wharton published an example project that shows how to use ActionBarSherlock with Gradle

Answer 3

You are using an older version of the android gradle plugin.
In the latest version 0.3 a lot has been improved in this area.

I would advise you to upstep to version 0.3 of this plugin. Be also aware that you then have to use a more recent version of gradle (1.3 or 1.4).

More information about how external libraries can be used in with this plugin.