# Annotation Processing 101

DevFeed: [Annotation Processing 101](<https://devfeed.tech/articles/annotation-processing-101-25468.md>)

Original publisher: [Read original article](<https://hannesdorfmann.com/annotation-processing/annotationprocessing101/>)

Author: Hannes Dorfmann

Published: 2015-01-10T09:00:00Z

Content type: tutorial

Language: en

Sources: [Hannes Dorfmann](<https://devfeed.tech/sources/hannes-dorfmann.md>)

Topics: [Java](<https://devfeed.tech/topics/java.md>), [Compiler](<https://devfeed.tech/topics/compiler.md>), [Code](<https://devfeed.tech/topics/code.md>)

Tags: [annotation-processor](<https://devfeed.tech/tags/annotation-processor.md>), [blog](<https://devfeed.tech/tags/blog.md>), [compiler](<https://devfeed.tech/tags/compiler.md>), [files](<https://devfeed.tech/tags/files.md>), [generate](<https://devfeed.tech/tags/generate.md>), [how-to](<https://devfeed.tech/tags/how-to.md>), [java](<https://devfeed.tech/tags/java.md>), [reflections](<https://devfeed.tech/tags/reflections.md>)

## AI overview

This tutorial explains Java annotation processing, including how it works at compile time, what annotation processors can generate, and what they cannot change in existing classes. It then begins a step-by-step implementation of a simple processor.

## Source excerpt

In this blog entry I would like to explain how to write an annotation processor. First, I am going to explain to you what annotation processing is, what you can do with that powerful tool and finally what you cannot do with it. In a second step we will implement a simple annotation processor step by step.