Java Reference
In-Depth Information
public class App {
@Unfinished(message = "Make sure that this
element is not null")
String size;
@Unfinished
public static void main(String[] args) {
System.out.println("Hello World
annotation!");
}
}
Although our annotation already looks like a standard annotation, it is not yet oper-
ational. For this, a class called
processor
must be available to the compiler. This
class will describe the action to take when an item is annotated with our custom an-
notation.
To achieve a custom processor for Java 6 annotation, we mainly need to implement
the
process()
methodofthe
javax.annotation.processing.Processor
in-
terface and define the annotations supported by this processor with the
@Suppor-
tedAnnotationTypes
annotation. The following code shows the processor of our
custom
Unfinished
annotation. As you can see, for the implementation of the
process()
method, we used the abstract class
AbstractProcessor
that imple-
ments the
Processor
interface. (This prevents us from having to implement all the
methods defined in this interface.)
@SupportedAnnotationTypes("com.packt.ch07.annotations.Unfinished")
public class UnfinishedProcessor extends
AbstractProcessor {
/**
* For the ServiceLoader
*/
public UnfinishedProcessor() {
}
@Override
