config - Enable Proguard for only two packages in large Android application

Question

Background

I am developing an Android application that relies on multiple external libraries (8 added as library project dependencies, 14 added as jar dependencies).

Some of these jar libraries are closed source an have already been obfuscated and some of them rely pretty heavily on reflection.

The application uses ZXing for QR code scanning/recognition and, without Proguard optimization, ZXing is quite slow (at least on Android).

At first, I only needed to optimize the com.google.zxing.** package using Proguard. In order to do that I've added the following Proguard options in my config file (the best I could figure out from this question):

-keep class !com.google.zxing.** { *; }
-keep interface !com.google.zxing.** { *; }
-keep enum !com.google.zxing.** { *; }
-dontwarn !com.google.zxing.**

I exported my application and it works like a charm.

Problem

Now, I want to use Proguard to obfuscate the application's classes.

I've tried changing the above to:

-keep class !(com.google.zxing.**, com.example.app.**) { *; }
-keep interface !(com.google.zxing.**, com.example.app.**) { *; }
-keep enum !(com.google.zxing.**, com.example.app.**) { *; }
-dontwarn !(com.google.zxing.**, com.example.app.**)
-keep com.example.app.activities.** { *; }
-keep com.example.app.receivers.** { *; }
-keep com.example.app.services.** { *; }
-keep com.example.app.views.** { *; }

The problem is that Proguard does not accept !(package.one.**, second.package.**) { *; } as a valid option for a -keep rule.

Another approach would be to put a -keep rule for every package in my application.

This approach has two big disadvantages:

1. adding or swapping libraries would require changing the Proguard config file

2. it makes updating libraries a pain, as some of them are obfuscated and, when recompiled by the library's developer, will change package names.

Obviously, I would like to avoid this approach as much as possible (because of the high number of external libraries).

Question

Is it possible to use Proguard to obfuscate just two packages, without defining a -keep rule for each of the other packages in my app? If so, how can I do this?

Answer 1

The correct syntax is a comma-separated list without any parentheses:

-keep class !com.google.zxing.**,!com.example.app.** { *; }

See the ProGuard manual > Usage > Filters.

Note that this single line already implies the two other lines for interfaces and enums. You can imply the -keep options for all subpackages by not letting the last wildcard match subpackages:

-keep class !com.google.zxing.**,!com.example.app.* { *; }