code-java-api-discoverylisted

# Java API Discovery Efficiently discover actual API signatures from compiled JARs using `javap`. This approach eliminates guessing and trial-and-error by examining the compiled bytecode directly. ## When to Use This Skill - Encountering compilation errors from incorrect method assumptions - Working with unfamiliar Java SDKs or libraries - Need to understand pagination patterns (offset vs cursor) - Dealing with union types or polymorphic responses - Verifying field existence before writing code - Documentation is incomplete, outdated, or ambiguous ## Core Workflow ### 1. Find the JAR ```bash # Gradle projects find ~/.gradle/caches -name "*library-name*.jar" -type f 2>/dev/null | head -5 # Maven projects find ~/.m2/repository -name "*library-name*.jar" -type f 2>/dev/null | head -5 # Project libs find . -name "*.jar" -type f 2>/dev/null ``` ### 2. List Package Contents ```bash # List all classes in a package jar tf /path/to/library.jar | grep "com/example/package" | head -20 # Find specific class jar tf /path/to/library.jar | grep -i "ClassName" ``` ### 3. Examine Class API ```bash # Show all public methods javap -cp /path/to/library.jar com.example.ClassName # Filter for getters javap -cp /path/to/library.jar com.example.ClassName | grep -E "public.*get" # Filter for setters/builders javap -cp /path/to/library.jar com.example.ClassName | grep -E "public.*(set|with|build)" # Show full signatures including generics javap -s -cp /path/to/library.jar com.example.C