http://katieleonard.ca/blog/2017/annotating-java/

CustomAnnotation.java

package com.keighty;

import java.lang.annotation.Documented;

@Documented
@interface CustomAnnotation {
    int id();
    String description();
    String author() default "[unknown]";
}

main.java

package com.keighty;

import com.sun.istack.internal.NotNull;

public class Main {

    @NotNull
    private final String message;

    public static void main(String[] args) {
	    Main main = new Main("This is a strong message");
        main.printSlogan();
        main.printBanner();
    }

    public Main(@NotNull String message) {
        this.message = message;
    }

    @CustomAnnotation(id = 1, description = "Custom description")
    public void printSlogan() {
        System.out.println("This method uses a @CustomAnnotation");
    }

    @CustomAnnotation(id = 2, description = "Custom banner", author = "keighty")
    public void printBanner() {
        System.out.println("This is a printed banner for: " + message);
    }

}