How to create additional parameters for your own annotations?

Question

Below is the annotation code

public @interface ColumnName { String value(); String datatype(); } 

I would like to make datatype optional parameter like

 @ColumnName(value="password") 

must be a valid code.

Answer 1

It seems that the first example in the official documentation says it all ...

 /** * Describes the Request-For-Enhancement(RFE) that led * to the presence of the annotated API element. */ public @interface RequestForEnhancement { int id(); String synopsis(); String engineer() default "[unassigned]"; String date() default "[unimplemented]"; } 

Answer 2

To make this optional, you can give it a default value:

 public @interface ColumnName { String value(); String datatype() default "String"; } 

Then, when using the annotation, you do not need to specify it.