COMPILE Time @Annotation Processing

Compile the annotation processor class.

javac src/FinalMethodAnnotationProcessor.java src/FinalMethod.java -d classes

Compile the source code with -processor key specifiing the annotation processor class

javac -cp classes/ -processor FinalMethodAnnotationProcessor -d classes src/Sample.java

Experiment

with FinalMethodAnnotationProcessor :

• Remove the final modifer of close method from the class Sample.java

• Compile the annoation processor, then compile the source code with preceding command.

with RetentionPolicy

• Change the retenion policy to (SOURCE, CLASS, RUNTIME) in the class FinalMethod.java.

• Compile the annotation processor, then compile the source code with preceding command.

• Run the command java -v classes/Sample then output may vary according to retention policy.

Example:

• When RetentionPolicy.CLASS the output will be:

  RuntimeInvisibleAnnotations:
  0: #27()
    FinalMethod

Note	Annotations with CLASS retention policy are included in the class file but are not accessible at runtime.

• When RetentionPolicy.RUNTIME the output will be:

  RuntimeVisibleAnnotations:
    0: #27()
      FinalMethod

Note	Annotations with RUNTIME retention policy are included in the class file and are accessible at runtime via reflection.

• When RetentionPolicy.SOURCE annotation is not visible in class file.

Note	Annotations with SOURCE retention policy are discarded by the compiler and are not included in the class file.