javax.validation to validate list of values?

Question

is there a way to use javax.validation to validate a variable of type string called colour that needs to have these values only(red, blue, green, pink) using annotations?

Answer 1

You can create a custom validation annotation. I will write it here (untested code!):

@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER })
@Retention(RUNTIME)
@Documented
@Constraint(validatedBy = InConstraintValidator.class)
public @interface In
{
    String message() default "YOURPACKAGE.In.message}";

    Class[] groups() default { };

    Class[] payload() default {};

    Object[] values(); // TODO not sure if this is possible, might be restricted to String[]
}

public class InConstraintValidator implements ConstraintValidator
{

    private Object[] values;

    public final void initialize(final In annotation)
    {
        values = annotation.values();
    }

    public final boolean isValid(final String value, final ConstraintValidatorContext context)
    {
        if (value == null)
        {
            return true;
        }
        return ...; // check if value is in this.values
    }

}