Understanding Java Annotations and Creating Custom Annotations

Java annotations are a powerful and flexible feature introduced in Java 5. They provide a way to add metadata to your code, making it more expressive and allowing tools and frameworks to generate code, perform validations, and more. In this extensive exploration, we will delve into the world of Java annotations, exploring what they are, how they work, and ultimately, how to create custom annotations with a high level of depth.

The Basics of Java Annotations
Annotations in Java are a form of metadata, providing information about the code to the compiler, runtime, or other tools. They are represented by the @ symbol followed by the annotation name. Some built-in annotations in Java include @Override, @Deprecated, and @SuppressWarnings.

Annotations can be applied to various program elements such as classes, methods, fields, parameters, and more. They serve multiple purposes, from indicating code relationships to providing hints for code analysis tools.

To use an annotation, you simply place it above the code element you want to annotate. For instance, the @Deprecated annotation can be applied to a method to indicate that it is no longer recommended for use:

@Deprecated
public void oldMethod() {
    // Deprecated method implementation
}

How Annotations Work
Annotations in Java are processed at compile time or runtime, depending on their retention policy. The retention policy is…