Y.S. Y.S. - 3 months ago 242
Android Question

Android - How to perform obfuscation with the JACK compiler?

Google has released a test version of their new JACK compiler for Android developers with Android Studio 2.1.

My question is, how do we enable obfuscation for the APK with JACK? The article below says that JACK performs obfuscation natively and eliminates the need for Proguard:

Whereas the following article says that JACK makes use of Proguard configuration files (i.e. the
file) for performing obfuscation:

It also says that

During this process Jack also handles any requested code minification (shrinking and/or obfuscation).

What exactly does this mean? Do we have to use the
option and define a
file containing the Proguard options?

In Summary:

  • How exactly do we go about enabling obfuscation with JACK? Can we
    bypass the use of Proguard, or does Proguard play a de-facto role in
    the obfuscation process, even if we compile with JACK?

  • Does JACK currently support obfuscation or not, and is it available
    in a stable (i.e. non-beta/canary) version of Android Studio?


I have already referred the following posts:

Further References:


The answer by Matt Insko is helpful, but I would like more detail, and a more precise, canonical answer. I have marked his [very good] answer correct for now, for lack of a better alternative.


J.A.C.K. obfuscation does not appear to be supported in the latest released Gradle Plugin (v2.1.0).

If you enable JACK when using the latest v2.1.0 plugin, it will tell you Jack requires Build Tools 24.0.0 or later requiring you to use the preview tools.

Using android gradle v2.2.0-alpha1, Build Tools-v24rc4, Platform Tools-v24rc3, and Sdk Tools-v25.1.7rc1 I was able to get obfuscation to be performed by JACK.

When enabled inside defaultConfig it complained Minifying the variant used for tests is not supported when using Jack., because minifyEnabled true was configured in the debug build.

So, I created a custom build type and enabled it there:

buildTypes {
    custom {
        minifyEnabled true
        proguardFiles 'proguard-android-JACK.txt-2.2.0-alpha1'
        jackOptions {
            enabled true

There was a problem when using proguardFiles getDefaultProguardFile('proguard-android.txt'). It errorred with: com.android.jack.api.v01.ConfigurationException: Error while parsing ..., . So, I just removed the lines it complained about and then just manually specified my modified configuration file.