How to create an Android Library Jar with gradle without publicly revealing source code?

Note: The answer has been edited. Please see the 07/28/2014 update below.

Here is a solution I ended up coming up with. There may be a better way available, but I have not found it yet.

android {    compileSdkVersion 18    buildToolsVersion "18.0.1"    defaultConfig {        minSdkVersion 10        targetSdkVersion 18    }    sourceSets {        main {            java {                srcDir 'src/main/java'            }            resources {                srcDir 'src/../lib'            }        }    }}task clearJar(type: Delete) {    delete 'build/libs/ProjectName.jar'}task makeJar(type: Copy) {    from('build/bundles/release/')    into('build/libs/')    include('classes.jar')    rename ('classes.jar', 'ProjectName.jar')}makeJar.dependsOn(clearJar, build)

Running gradlew makeJar creates a ProjectName.jar in the build/libs directory. The structure of this jar is as follows:

ProjectName.jar    \- lib    |   \- armeabi    |       \- libNativeFirst.so    |       \- libNativeSecond.so    \- com        \- package            \- sdk                \- PackageSDK.class

This is the exact result I needed. I am now able to use ProjectName.jar successfully in other projects.

EDIT: While I am able to use the resulting jar in projects within Android Studio, I cannot do so in projects created in ADT due to a warning about native code being present inside a jar file. Supposedly there is a flag to turn off this check in settings, but it does not function correctly. Thus, if you want to create a library that uses native code, those using ADT will have to manually copy the armeabi directory into libs/.

07/28/2014 Update:

As of Android Studio 0.8.0, Gradle output directories have been changed and the configuration outlined above will not work. I have changed my configuration to the following:

task clearJar(type: Delete) {    delete 'build/outputs/ProjectName.jar'}task makeJar(type: Copy) {    from('build/intermediates/bundles/release/')    into('build/outputs/')    include('classes.jar')    rename ('classes.jar', 'ProjectName.jar')}

IMPORTANT: Please note that ProjectName.jar will now be placed into build/outputs/ and NOT into build/libs/.

Just to add a slight alternative to @BVB's answer (although heavily based on it) here's what I had to do to output a jar myapp-api.jar which was for a Java only project that dealt with rest API interaction. It's dependant on Android.jar hence the need to use apply plugin: 'com.android.application' rather than just apply plugin: 'java'

Calling ./gradlew build jar from the myJavaAPIProject to build and generate the .jar to myJavaAPIProject/build/libs/myapp-api.jar

build.gradle

//Even though this is a Java project, we need to apply the android plugin otherwise it cannot find the SDK/android.jar and so cannot compileapply plugin: 'com.android.application'dependencies {    //this ensures we have gson.jar and anything else in the /lib folder    compile fileTree(dir: 'lib', include: '*.jar')}repositories {    mavenCentral()}android{    compileSdkVersion 21    buildToolsVersion "21.0.1"    defaultConfig {        minSdkVersion 10        targetSdkVersion 21    }    sourceSets {        main {            java {                //points to an empty manifest, needed just to get the build to work                manifest.srcFile 'AndroidManifest.xml'                //defined our src dir as it's not the default dir gradle looks for                java.srcDirs = ['src']            }        }    }    //enforce java 7    compileOptions {        sourceCompatibility JavaVersion.VERSION_1_7        targetCompatibility JavaVersion.VERSION_1_7    }}//Actually created the .jar filetask jar(type: Jar) {    //from android.sourceSets.main.java    from 'build/intermediates/classes/release/'    archiveName 'myapp-api.jar'}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?><!-- this is a dummy file needed to ensure gradle validates and builds ok --><manifest    package="com.myapp.android"    />