New posts

2026-11-06 21:43:25 +05:30
parent dfd3a830cd
commit d7d5689f05
40 changed files with 1359 additions and 0 deletions
@@ -0,0 +1,40 @@
+# annotation-processor
+
+Companion code for the ankurm.com post *"Custom Annotations and Annotation Processors in Java:
+Generate Code at Compile Time."* A module of `java-core-examples`; itself a small two-module Maven build.
+
+## Versions this was built and tested against
+
+| Component | Version |
+|---|---|
+| JDK | 25.0.5+8 (Temurin, LTS) |
+| Maven | 3.9.11 |
+| maven-compiler-plugin | 3.16.0 |
+| maven-surefire-plugin | 3.6.1 |
+| JUnit Jupiter | 6.1.3 |
+
+## Run it
+
+```bash
+export JAVA_HOME=/path/to/jdk-25
+mvn -B clean test          # from this directory: builds the processor, then the demo that uses it
+scripts/run-all.sh         # also regenerates every file in output/
+```
+
+## Files
+
+| Path | What it is |
+|---|---|
+| `processor/.../GenerateBuilder.java` | The annotation (SOURCE retention, TYPE target, two members with defaults) |
+| `processor/.../BuilderProcessor.java` | The `AbstractProcessor` that writes `<Type>Builder` through `Filer`, reports problems through `Messager` |
+| `processor/src/main/resources/META-INF/services/javax.annotation.processing.Processor` | Registration |
+| `processor/src/test/.../Compilation.java`, `ProcessorCompileTest.java` | In-memory `javax.tools.JavaCompiler` harness and its tests (writes `output/09`) |
+| `demo/.../Person.java`, `Pizza.java` | Consumers of `@GenerateBuilder` (a record and a class) |
+| `demo/.../annotations/*` | SOURCE / CLASS / RUNTIME annotations, `@Inherited`, `@Repeatable`, members and defaults |
+| `demo/.../RetentionDemo.java`, `RuntimeValidatorDemo.java` | What reflection sees; a reflection-based validator |
+| `demo/src/test/...` | Runtime tests of the generated builders and of the reflection behaviour |
+| `bad/Shape.java` | Deliberately invalid input for the compile-error transcript |
+| `output/01..10` | Captured runs; the post quotes these verbatim |
+
+`demo/pom.xml` has two throwaway profiles (`classpath-only`, `classpath-proc-full`) used only to capture
+`output/08`.