VibeCoding/.agents/skills/r8-analyzer/references/REFLECTION-GUIDE.md

A categorized summary of the keep rule examples, including the code patterns to look for (imports/usage) and the corresponding suggested rules.

1. Reflection: Classes Loaded by Name

Scenario: A library or app loads a class dynamically using a string name

• Look for: Class.forName("..."), getDeclaredConstructor().newInstance(), or interfaces used for dynamic loading.

• Example Code: kotlin val taskClass = Class.forName(className) val task = taskClass.getDeclaredConstructor().newInstance() as StartupTask

• Suggested Keep Rule: ```proguard

  -keep class * implements com.example.library.StartupTask { (); } ```

2. Reflection: Classes Passed using ::class.java

Scenario: An app passes a class reference directly to a library function.

• Look for: ::class.java (Kotlin) or .class (Java) passed as an argument.

• Example Code: kotlin fun <T> register(clazz: Class<T>) { } // Usage: register(MyService::class.java)

• Suggested Keep Rule: ```proguard

  Keep the class itself (R8 usually handles this, but explicit rules ensure stability)

  -keep class com.example.app.MyService { (); } ```

3. Annotation-Based Reflection (Methods/Classes)

Scenario: Using custom annotations to mark methods or classes for reflective execution.

Look for: Custom @interface definitions and getDeclaredMethods() filtered by annotation. Example Code: kotlin annotation class ReflectiveExecutor // Logic: find methods annotated with @ReflectiveExecutor and invoke them

• Suggested Keep Rule: ```proguard # Keep the annotation itself -keep @interface com.example.library.ReflectiveExecutor

Keep members of any class annotated with this specific annotation

-keepclassmembers class * { @com.example.library.ReflectiveExecutor *; } ```

4. Optional Dependencies (Soft Dependencies)

Scenario: A core library checks if an optional module is present in the classpath.

• Look for: try-catch blocks around Class.forName() used to toggle features.
• Example Code: ```kotlin private const val VIDEO_TRACKER_CLASS = "com.example.analytics.video.VideoEventTracker"

try { Class.forName(VIDEO_TRACKER_CLASS).getDeclaredConstructor().newInstance() } catch (e: ClassNotFoundException) { /* skip feature */ } ```

• Suggested Keep Rule: `proguard

  Preserve the optional class so the check doesn't fail due to shrinking

  -keep class com.example.analytics.video.VideoEventTracker { (); }`

5. Accessing Private Members

Scenario: Using reflection to access internal fields or methods not exposed with public APIs.

• Look for: getDeclaredField("...") or getDeclaredMethod("...") followed by isAccessible = true.

• Example Code: kotlin val secretField = instance::class.java.getDeclaredField("secretMessage") secretField.isAccessible = true

• Suggested Keep Rule: ```proguard

  Specifically keep the private field/method by name and type

  -keepclassmembers class com.example.LibraryClass { private java.lang.String secretMessage; } ```

6. Parcelable (Manual Implementation)

Scenario: Implementing Parcelable without using the @Parcelize annotation.

• Look for: implements Parcelable and a static CREATOR field.

• Example Code: kotlin class MyData : Parcelable { // Manual implementation with CREATOR field }

• Suggested Keep Rule: (Note: If using import kotlinx.parcelize.Parcelize, R8/ProGuard rules are generated automatically. If manual, use the following:) proguard -keepclassmembers class * implements android.os.Parcelable { static android.os.Parcelable$Creator CREATOR; }

7. Enums and Obfuscation

Scenario: App uses Enum.valueOf("STRING_NAME") indirectly (e.g.,using JSON deserialization) and the enum names get obfuscated.

• Look for: Unnecessary generic Enum keep rules in ProGuard files.

• Example Code: ```proguard

  Unnecessary rule

  -keepclassmembers enum * { *; } ```

• Suggested Keep Rule: *(Note: The default proguard-android-optimize.txt already contains the optimal rules for Enums (keeping values() and valueOf(String)). Any additional manual rules for Enums are redundant.) # No manual rule needed. Use default proguard-android-optimize.txt.