Annotation Processor - How to get the Class it is processing

Question

I am trying to write a custom Anntoation processor. The annotation processor will process each class file at compile time to check annotations, But how am i able to get the class that it is currently processing? I am only able to get the class name in the following codes.

public class AnnotationProcessor extends AbstractProcessor {
  ......
    @Override
     public boolean process(Set<? extends TypeElement> annotations,
        RoundEnvironment roundEnv) {

     Set<? extends Element> rootE=roundEnv.getRootElements();
       for(Element e: rootE) {
        if(e.getKind()==ElementKind.CLASS) {
            String className= e.getSimpleName().toString();
            processingEnv.getMessager().printMessage( javax.tools.Diagnostic.Kind.WARNING,className, e); 
        }
     }
}

Answer 1

You are unable to access the Class the Annotation Processor is processing because the Class has not been compiled yet. Instead Java offers the analogous Elements api for reflection-style inspection of the input source.

The Element (which you found by using roundEnv.getRootElements()) has much more information about the class being compiled than just its name. A ton of useful information can be found by using the ElementVisitors:

http://docs.oracle.com/javase/6/docs/api/javax/lang/model/element/ElementVisitor.html http://docs.oracle.com/javase/6/docs/api/javax/lang/model/util/ElementKindVisitor6.html

Including the classes constructor, methods, fields, etc.

Here's how to use it:

public class AnnotationProcessor extends AbstractProcessor {
......
    @Override
     public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {

         Set<? extends Element> rootE=roundEnv.getRootElements();
         for(Element e: rootE) {
             for(Element subElement : e.getEnclosedElements()){
                 subElement.accept(new ExampleVisitor(), null); // implement ExampleVisitor
             }
        }
    }
}