Simple gradle task to create a fatJar that includes all dependencies except for specific jars. Snippet below doesn't include android.jar file.

fatJar_build.gradle

task fatJar(type: Jar, dependsOn: 'compileJava') {
    from {
        sourceSets.main.output.classesDir
    }

    // Add all dependencies except for android.jar to the fat jar
    from {
        configurations.compile.findAll {
            it.getName() != 'android.jar'
        }.collect {
            it.isDirectory() ? it : zipTree(it)
        }
    }

    archiveName = 'fatJar.jar'
}