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

Question

I would like to create a Jar out of an Android library project. It is set up the following way:

ProjectName
    \\- lib
    |   \\- lib
    |       \\- armea         


        

Answer 1

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 compile
apply 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 file
task jar(type: Jar) {
    //from android.sourceSets.main.java
    from 'build/intermediates/classes/release/'
    archiveName 'myapp-api.jar'
}

AndroidManifest.xml