Java Annotation Processing
summary
Creates a custom @Builder annotation and a processor that uses javax.annotation.processing.AbstractProcessor and Google auto-service to write .java files via the compiler Filer, keeping processing at compile-time generation instead of reflection. Demo project shows generated builder classes added during compilation, then measures runtime: reflection build ~39 ms vs generated builder ~3 ms (order-of-magnitude faster). Implementation uses a separate processor module, transforms javax Elements into plain descriptors, validates targets, and writes source files with PrintWriter; the approach works and improves performance.
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chapters (9)
- 0:00Java annotation processing
- 6:02Java annotations importance
- 14:14Compile-time vs runtime
- 24:46Gradle setup for annotation processing
- 33:15Custom Builder annotation
- 42:46Generating classes from annotations
- 51:44Performance vs reflection
- 55:04Lombok and annotation processing
- 57:39Q&A with Oscar Camacho
