ProGuard: How to Keep All Implementation Class Names Except One

Introduction

ProGuard is a popular tool used to shrink, optimize, and obfuscate Java code, making it more efficient and secure. One of the most powerful features of ProGuard is its ability to configure the obfuscation process to suit specific needs. In this article, we’ll explore how to keep all implementation class names except one using ProGuard.

Why Keep Class Names?

There are several reasons why you might want to keep certain class names from being obfuscated. For example:

• Debugging: Keeping class names intact can make it easier to debug your application, as the original class names are preserved.

• API Compatibility: If your application provides a public API, you may want to keep certain class names unchanged to maintain compatibility with other systems.

• Library Dependencies: Some libraries require specific class names to function correctly. By keeping these names intact, you can ensure seamless integration with these libraries.

The Basics of ProGuard Configuration

Before diving into the specifics of keeping class names, let’s cover the basics of ProGuard configuration. ProGuard uses a configuration file (usually `proguard.cfg` or `proguard.pro`) to define the rules for obfuscation. This file consists of a series of directives, each specifying a rule for ProGuard to follow.

// Sample ProGuard configuration file
-keep class * {
    public ();
}

-keepclassmembers class * {
    public ();
}

In this example, the `-keep` directive specifies that all classes with a public constructor should be kept intact. The `-keepclassmembers` directive specifies that all class members (methods, fields, etc.) with a public constructor should also be kept intact.

Keeping All Implementation Class Names Except One

To keep all implementation class names except one, we’ll use a combination of ProGuard directives and filters. Let’s assume we want to keep all class names except for the `com.example.ExampleClass` class.

// Keep all classes except com.example.ExampleClass
-keep class !com.example.ExampleClass {
    *;
}

// Keep all class members except for those in com.example.ExampleClass
-keepclassmembers class !com.example.ExampleClass {
    *;
}

In this example, the `!` symbol is used to negate the filter, specifying that all classes except `com.example.ExampleClass` should be kept intact. The `*` wildcard is used to match all members (methods, fields, etc.) of the classes.

Using Wildcards and Patterns

ProGuard allows you to use wildcards and patterns to specify complex filters. For example, to keep all classes in the `com.example` package except for `com.example.ExampleClass`, you can use the following filter:

-keep class com.example.** { *; }
-keepclassmembers class com.example.** { *; }

-keep !class com.example.ExampleClass {
    *;
}

-keepclassmembers !class com.example.ExampleClass {
    *;
}

In this example, the `com.example.**` pattern matches all classes in the `com.example` package and its subpackages. The `!com.example.ExampleClass` filter is then used to exclude the `com.example.ExampleClass` class from the keep list.

Additional Tips and Tricks

Here are some additional tips and tricks to help you customize your ProGuard configuration:

• Use the `-keeppackagenames` directive to keep package names intact.

• Use the `-keepattributes` directive to keep specific attributes (e.g., annotations, signatures) intact.

• Use the `-printclassnames` option to print a list of all class names that ProGuard encounters during the obfuscation process.

Conclusion

In this article, we’ve covered how to keep all implementation class names except one using ProGuard. By using a combination of directives and filters, you can customize the obfuscation process to suit your specific needs. Remember to use wildcards and patterns to specify complex filters, and don’t hesitate to experiment with different configurations to achieve the desired results.

Directive	Description
-keep	Specifies classes or class members to keep intact.
-keepclassmembers	Specifies class members (methods, fields, etc.) to keep intact.
-keeppackagenames	Specifies package names to keep intact.
-keepattributes	Specifies attributes (e.g., annotations, signatures) to keep intact.
-printclassnames	Prints a list of all class names encountered during the obfuscation process.

By following these guidelines and experimenting with different configurations, you’ll be able to optimize your ProGuard setup to meet the specific needs of your project.

Frequently Asked Question

Get ready to shield your Android app’s code from prying eyes with ProGuard! But, what if you want to keep all implementation class names except one? We’ve got you covered!