How to create optional parameters for own annotations?

Question

Following is the annotation code

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

I would like to make datatype an optional parameter, for example

@ColumnName(value="password")  

should be a valid code.

Answer 1

Seems like 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 it optional you can assign it a default value like that:

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

Then it doesn't need to be specified when using the Annotation.