Jakarta Bean Validation

The focus of Bean Validation 2.0 is supporting and taking advantage of Java SE 8.

For instance type annotations are used to validate the elements of generic containers: List<@NotNull @Email String> emails. There are new built-in constraints (e.g. @NotBlank, @NotEmpty, @Email, @Positive and @Negative) and all built-in constraints are repeatable annotations now. Bean Validation 2.0 also supports the new Java 8 date and time types (JSR 310), the property types defined by JavaFX (StringProperty etc.) as well as java.util.Optional.

To learn more about all the new features in Bean Validation 2.0, check out this presentation which I recently gave at the jdk.io conference.

Since the Public Review Draft (Beta 2) we’ve primarily focused on improving the new Bean Validation 2.0 features, e.g. by clarifying ambiguities in the spec, fixing bugs in the API, adding more examples etc.

In terms of API changes, we’ve followed up on our community survey on the new built-in constraints @Positive and @Negative and removed the strict() attribute in favor of separate annotations: @PositiveOrZero and @NegativeOrZero. As suggested by the community feedback, we’ve found that those separate annotations improve readability of code using the constraints. In order to stay consistent, we’ve also removed orPresent() from @Past and @Future in favor of @PastOrPresent and @FutureOrPresent. We think the same argument of readability applies; if you have any thoughts on these changes, please let us know.

Another API change (BVAL-655) relates to how container element constraints are exposed in the constraint metadata API. In case an overriding method of a sub-type specializes the return type of the overridden method (co-variant return type) it’s now possible to obtain the constraint metadata for the return type of the super-type method as well as of the sub-type method. Refer to the spec for the complete metadata API definition and an extensive example of its usage.

The complete list of all 38 issues resolved for the CR 1 release can be found in the BVAL JIRA project. Corresponding releases of our reference implementation Hibernate Validator 6 and the TCK can be expected within the next few days.

The Proposed Final Draft is pretty much what the expert group thinks should make up Bean Validation 2.0, i.e. it should be considered feature-complete. Any further changes will essentially be bug fixes, further clarifications in the wording, formatting and other polishing. If you’d like to help, reviewing the specification changes would be the best thing to do at this point. Also it’d be of great help if you tried out the reference implementation in your applications and let us know how it works. Any feedback is welcomed!

To post your feedback, just add a comment below, send a message to our mailing list or post in the Bean Validation forum. If you find a bug or have a specific feature request, please raise it in the issue tracker.

Everything in Bean Validation is open source, so you also can send in actual patches: be it to the API, the spec document, the TCK or the reference implementation. If you are interested, you can find out all the details to get started in the contribution guide.

Finally, let me say a huge "Thank You" to all the fine folks who helped to deliver this Proposed Final Draft:

Your efforts are greatly appreciated!