Procedure 13.5. Create a Constraint Annotation

1. Open a Java project in Red Hat JBoss Developer Studio.

2. Create a Data Set

   A constraint annotation requires a data set that defines the acceptable values.
   1. Right click on the project root folder in the Project Explorer panel.
   2. Select New → Enum.
   3. Configure the following elements:
      • Package:
      • Name:
   4. Click the Add... button to add any required interfaces.
   5. Click Finish to create the file.
   6. Add a set of values to the data set and click Save.

   Example 13.25. Example Data Set

   package com.example;
   
   public enum CaseMode {
       UPPER,
       LOWER;
   }
   

3. Create the Annotation File

   Create a new Java class.
4. Configure the constraint annotation and click Save.

   Example 13.26. Example Constraint Annotation File

   package com.mycompany;
   
   import static java.lang.annotation.ElementType.*;
   import static java.lang.annotation.RetentionPolicy.*;
   
   import java.lang.annotation.Documented;
   import java.lang.annotation.Retention;
   import java.lang.annotation.Target;
   
   import javax.validation.Constraint;
   import javax.validation.Payload;
   
   @Target( { METHOD, FIELD, ANNOTATION_TYPE })
   @Retention(RUNTIME)
   @Constraint(validatedBy = CheckCaseValidator.class)
   @Documented
   public @interface CheckCase {
   
       String message() default "{com.mycompany.constraints.checkcase}";
   
       Class<?>[] groups() default {};
   
       Class<? extends Payload>[] payload() default {};
       
       CaseMode value();
   
   }