Mastering R8 Configuration: A Practical Guide to Optimization and Debugging

Enabling R8 is one of the most effective steps you can take to shrink, obfuscate, and optimize your Android app. But what happens when R8's optimizations lead to a runtime crash like ClassNotFoundException or NoSuchMethodError? For many developers, the immediate fix is a broad, "catch-all" keep rule—or worse, disabling R8 altogether.

This session provides a practical, step-by-step guide to mastering R8's configuration, not just enabling it. We'll start with a sample app, enable R8, and intentionally trigger a common crash (e.g., from reflection).

You'll learn to:
- Use R8's tools like retrace to de-obfuscate the stack trace and find the true root cause.
- Analyze R8's configuration path and output files (like configuration.txt) to understand why R8 removed the specific class or method.

- Write a specific, narrow keep rule that fixes the bug without unnecessarily bloating your app.

This session will give you the tools and confidence to diagnose any R8-related issue and write precise, efficient keep rules.

Attendees will leave this session knowing how to:

- Implement R8 in a new or existing Android project correctly.
- Debug minified apps by de-obfuscating stack traces to find the real source of a crash.
- Analyze R8's build outputs to understand what code was kept, removed, and why.
- Identify the root cause of common R8 issues, especially those related to reflection, serialization, or JNI.
- Write effective, narrow keep rules that target the specific problem instead of using broad rules that harm optimization.
- Verify R8's configuration to ensure your rules are being applied as expected and are having the intended effect.