innovationhilt.blogg.se - Java annotations for in development code

JAVA ANNOTATIONS FOR IN DEVELOPMENT CODE HOW TO
JAVA ANNOTATIONS FOR IN DEVELOPMENT CODE CODE

You will not use the annotation often, but now you know it exists, if you should need it. When generating JavaDoc for the MySuperClass class, the is now included in the JavaDoc. When an annotation type is annotated with meta annotation Retention, RetentionPolicy has three possible values: ( RetentionPolicy. This meta annotation denotes the level till which this annotation will be carried.

When a class is annotated with annotation of type that is annotated with Inherited, then its super class will be queried till a matching annotation is found. This meta annotation denotes that the annotation type can be inherited from super class. When a annotation type is annotated with then wherever this annotation is used those elements should be documented using Javadoc tool.

JAVA ANNOTATIONS FOR IN DEVELOPMENT CODE CODE

IDE benefits using this javadoc as it is able to render information about the code as we develop. Javadoc facility gives option for understanding the code in an external way, instead of opening the code the javadoc document can be used separately. Therefore, we can use a tool and parse those comments and prepare a javadoc document which can be distributed separately. The way we need to add is organized using a syntax. Javadoc is an additional step over it, where we add information about the class, methods, variables in the source code. We have basic java comments infrastructure using which we add information about the code / logic so that in future, another programmer or the same programmer can understand the code in a better way. It can be parsed by the compiler, annotation processing tools and can also be made available at run-time too. In other words, organized data about the code, embedded within the code itself.

Filer: Like the name suggests with Filer you can create files.Annotation is code about the code, that is metadata about the program itself.

Types: A utils class to work with TypeMirror (more information later).

Elements: A utils class to work with Element classes (more information later).

Handy, isn’t it? In getSupportedAnnotationTypes() we specify that is processed by this processor. We can use annotation processors in our annotation processor. This AutoService annotation processor has been developed by Google and generates the META-INF/services/ file. In the first line you see What’s that? It’s an annotation from another annotation processor. Package com.example public class MyProcessor extends AbstractProcessor Every Processor extends from AbstractProcessor as follows: The generated java file will be compiled by javac as any other hand written java source file. So you can not manipulate an existing Java class for instance adding a method. What does that exactly means? You can generate Java code! The generated java code is in a generated. So it has become popular in the last few years.Īn annotation processor for a certain annotation takes java code (or compiled byte code) as input and generate files (usually. It took some time until the java world realized the power of annotation processing.

Annotation processing is already available since Java 5 but a useable API is available since Java 6 (released in December 2006). If you are not familar with annotations you can find more information in the official java documentation.

JAVA ANNOTATIONS FOR IN DEVELOPMENT CODE HOW TO

At this point I assume that you already know what an annotation is and how to declare an annotation type. You can register your own annotation processor for certain annotations. Annotation processing takes place at compile time (compile time = the time when the java compiler compiles your java source code).Īnnotation processing is a tool build in javac for scanning and processing annotations at compile time. To clarify a very important thing from the very beginning: we are not talking about evaluating annotations by using reflections at runtime (run time = the time when the application runs). In a second step we will implement a simple annotation processor step by step. 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 this blog entry I would like to explain how to write an annotation processor.