Android studio generates aar with addiction

Question

I have a library project (A) that refers to another jar file (B.jar), but after creating the aar file the jar file (B.jar) is not included in the output aar file and when using this aar file, I got a NoClassDefFoundError .

Is there a way to make gradle a collection of all the dependency classes in the output aar file? this is my build.gradle:

 apply plugin: 'com.android.library' repositories { mavenCentral() } android { buildTypes { release { runProguard true proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.txt' } } } dependencies { compile project(':common') compile fileTree(dir: 'libs', include: ['*.jar']) } 

Answer 1

Is there a way to make gradle bind all the dependency classes to output aar file?

Yes, there is a way to do this, I have encountered this problem before. But it will be a long story, carry me.

Background

When you specify the dependency in the build.gradle file, you tell gradle to load the artifact (AAR / JAR) from the Maven repository. So gradle needs two things:

• Maven Storage Location
• addiction itself

You specify the Maven repository at the top level of build.gradle

 repositories { jcenter() google() } 

and indicate the dependency on the project level build.gradle

 dependencies { compile 'com.example:mylibrary:1.0.1' } 

How does gradle / Maven know that mylibrary needs other dependencies? From your Dependency POM file .

POM example

Let me use Square OkHttp as an example, you can find this artifact at mvnrepository.com.

OkHttp has a POM file. You can click this link to show the full XML, I show you the interesting part, which is a block of dependencies.

 <project> <modelVersion>4.0.0</modelVersion> <parent>...</parent> <artifactId>okhttp</artifactId> <name>OkHttp</name> <dependencies> <dependency> <groupId>com.squareup.okio</groupId> <artifactId>okio</artifactId> </dependency> <dependency> <groupId>com.google.android</groupId> <artifactId>android</artifactId> <scope>provided</scope> </dependency> <dependency> <groupId>com.google.code.findbugs</groupId> <artifactId>jsr305</artifactId> <scope>provided</scope> </dependency> </dependencies> <build>...</build> </project> 

OkHttp requires dependencies on other artifacts. Okio, Android and jsr305. But when you include OkHttp in your project, you do not need to include Okio, Android and jsr305 in your project. Why is this?

Because gradle / Maven will search the POM files and load the dependencies for you. More NoClassDefFoundError .

Your library project

Back to your question, how to "combine" your library project into a single .aar? Here are the steps:

• Publish your dependencies (your JAR or AAR) in the Maven repository.

There is a high probability that your dependencies already exist in mvnrepository, if it does not exist, you can send your dependencies to bintray, mvnrepository or host your own Maven repository.

2. Create a POM file for AAR.

As in the OkHttp dependency block, you put library dependencies in it.

3. Submit your AAR library to the Maven repository.

You can use mvndeploy to submit your library to the Maven repository.

 mvn deploy:deploy-file \ -DgroupId=com.example \ -DartifactId=your-library \ -Dversion=1.0.1 \ -Dpackaging=aar \ -Dfile=your-library.aar \ -DpomFile=path-to-your-pom.xml \ -DgeneratePom=true \ -DupdateReleaseInfo=true \ -Durl="https://mavenUserName: [e-mail] /repository/maven-releases/" 

If you do not want to do steps 2 and 3 manually, as you can assume, "there is a gradle plugin for this!" Plugin android-maven-publish , credit for: wupdigital to facilitate this process.

Now you can use the gradle command to publish your library:

 gradle yourlibrary:assembleRelease yourlibrary:publishMavenReleaseAarPublicationToMavenRepository 

How to share your library project

The next time your teammate asks for your library, you can give them two things:

• Maven repository containing your library and its dependencies
• Your group, artifact, and your library name

What is it! No need to specify dependencies for your peers.

Greetings 🥂

Answer 2

What you are trying to do is impossible - at least not possible in the way you described it above.