What are some examples of annotation processing in Java?

What are some examples of annotation processing in Java?

Annotation processing in Java allows developers to generate code, XML files, and other resources at compile time. Examples include generating getters and setters, creating custom annotations, and processing them with tools like Lombok.

Can you show me a simple example of a custom annotation?

Sure! Here's a simple example:

import java.lang.annotation.*;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface MyCustomAnnotation {
    String value();
}

This defines a custom annotation that can be applied to classes.

How do I process this annotation?

You can process the annotation using an annotation processor. Here's a basic example:

import javax.annotation.processing.*;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.TypeElement;

@SupportedAnnotationTypes("MyCustomAnnotation")
@SupportedSourceVersion(SourceVersion.RELEASE_8)
public class MyAnnotationProcessor extends AbstractProcessor {
    @Override
    public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
        // Processing logic here
        return true;
    }
}

What tools can I use for annotation processing?

You can use tools like Lombok, Dagger, and AutoValue for annotation processing in Java. They simplify code generation and dependency injection.