jsf JSF Annotations Introduction to annotations

Example

Why annotations?

Generally we use annotation to facilitate the development and to make the code more clear and clean.

What are annotations?

Java 5 annotations provide standardization of metadata in a general goal. This metadata associated with Java features can be exploited in the compilation or execution.

Java was modified to allow the implementation of annotations:

• A dedicated syntax was added in Java to allow the definition and use of annotations.
• bytecode is enhanced to allow storage of annotations.

Where can annotations be used?

Annotations can be used with :

packages, classes, interfaces, constructors, methods, fields, parameters, variables or annotations themselves.

Categories of annotation

There are three categories of annotation:

• Markers: These annotations do not have an attribute

For example @Deprecated, @Override ...

• Single value annotation: these annotations have only one attribute

For example @MyAnnotation ( "test")

• Full annotations: these annotations have multiple attributes

For example @MyAnnotation (arg1 = "test 3", arg2 = "test 2", arg3 = "test3")

Like we see before you can create your own annotation