What does the @ sign means in java?

Question

Below is the code snippet.

@Intercepts({@Signature(
type= Executor.class,
method = \"update\",
args = {MappedStatement.class,Object.class})})
public class
<         


        

Answer 1

It's an Annotation.

Annotations are a form of metadata. They provide data about a program that is not part of the program itself. Annotations have no direct effect on the operation of the code they annotate.

Annotations do affect the way programs are treated by tools and libraries, which can in turn affect the semantics of the running program. Annotations can be read from source files, class files, or reflectively at run time.