Java 自訂 Annotation

http://www.coderanch.com/t/528859/java/java/Create-custom-annotation

@Retention(RetentionPolicy.RUNTIME)   
@interface Todo {   
    String value();   
}   

import java.lang.annotation.*;   
   
@Todo("Hello world")   
public class Example {   
    public static void main(String[] args) {   
        Todo task = Example.class.getAnnotation(Todo.class);   
        System.out.println("Found annotation: " + task.value());   
    }   
}