Скачать или смотреть Resolving the java.lang.IllegalArgumentException Error in Proguard When Upgrading to Java 11

Encounter a `java.lang.IllegalArgumentException` while using Proguard after upgrading to Java 11? Discover the solution that works!
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Resolving the java.lang.IllegalArgumentException Error in Proguard When Upgrading to Java 11

Upgrading your Java version can sometimes lead to unexpected challenges, especially when using tools like Proguard for obfuscation and optimization of your code. A common issue that arises during this transition is the dreaded java.lang.IllegalArgumentException related to the inability to find a common superclass.

In this guide, we'll dissect this problem, the specific error message encountered, and provide a solution that will help you tackle this issue effectively.

The Problem: Encountering the IllegalArgumentException

After switching your project's Java version from 8 to 11, you might face an error while running Proguard. The stack trace reveals something critical:

[[See Video to Reveal this Text or Code Snippet]]

This indicates that Proguard is struggling to resolve the common superclass of two classes in the Akka Actor library. This is an issue often exacerbated by changes in how Java manages packages and modules.

Expected Proguard Configuration

You might be using a Proguard configuration that looks like this:

[[See Video to Reveal this Text or Code Snippet]]

That said, despite your efforts with various -keep directives specifically for Akka, the error persists.

The Solution: Adding the Right Library Jars

The key to resolving the IllegalArgumentException lies in instructing Proguard to recognize the correct Java modules. Specifically, you would need to add the following parameter to your Proguard configuration:

[[See Video to Reveal this Text or Code Snippet]]

Understanding the Solution Components

What is -libraryjars?

This option tells Proguard where to find the library jars that need to be included during the Shrink and Optimize phase.

Why $java_home_11/jmods/java.base.jmod?

In Java 11, the module system was introduced, which changes how classes are organized. Specifying the path to the java.base.jmod ensures that Proguard can correctly identify and work with classes that reside in the base module of Java, including key classes used by Akka.

Additional Suggestions

If you still encounter issues, consider using the -dontpreverify option temporarily while troubleshooting. However, be cautious with this setting as it prevents Proguard from verifying the class structure, which might lead to potential runtime errors.

Make sure your Akka library is compatible with Java 11. You may want to look into updated versions that specifically support this Java version.

Conclusion

Transitioning from Java 8 to 11 can unveil hidden compatibility issues, especially in tools like Proguard. By implementing the solution discussed, you can effectively resolve the java.lang.IllegalArgumentException.

For developers using Akka, ensuring that Proguard has access to the necessary library jars is crucial in avoiding similar roadblocks in the future. Happy coding!