Hibernate Validator 6 is going to be the Reference Implementation of Bean Validation 2.0. This Alpha2 release is coordinated with the 2.0.0.Alpha2 release of the Bean Validation specification.

It is also a playground used to validate future enhancements of the Bean Validation specification so feedback on the subjects presented here is very welcome!

Note that Hibernate Validator 6 requires JDK 8 or above.

If you missed the Alpha1 release, consulting its announcement might be beneficial to you before continuing your reading.

What’s new since Alpha1

Improved container element validation support

Container element validation support is the big new feature of Bean Validation 2.0 and it got some more love during this cycle.

Programmatic API and XML support

To obtain the equivalent of:

public class FishTank {

    private Optional<@Valid FishTankModel> model;

    private Map<@Size(min = 3, max = 10) String, @Min(1) Integer> fishCountByType;

it is now possible to declare container element type constraints and cascaded validation either via an XML mapping configuration (which is part of the Bean Validation 2.0 specification):

    <bean class="com.acme.FishTank" ignore-annotations="false">
        <field name="model">
                <valid />
        <field name="fishCountByType">
            <containerElementType typeArgumentIndex="0">
                <constraint annotation="javax.validation.constraints.Size">
                    <element name="min">
                    <element name="max">
            <containerElementType typeArgumentIndex="1">
                <constraint annotation="javax.validation.constraints.Min">
                    <element name="value">

or via the (implementation specific) programmatic API:

ConstraintMapping newMapping = config.createConstraintMapping();
    .type( FishTank.class )
        .property( "model", FIELD )
        .property( "fishCountByType", FIELD )
            .containerElementType( 0 )
                .constraint( new SizeDef().min( 3 ).max( 10 ) )
            .containerElementType( 1 )
                .constraint( new MinDef().value( 1 ) );

Other improvements

We also made a couple of more minor improvements:

  • the TYPE_ARGUMENT node type has been renamed to CONTAINER_ELEMENT (type argument don’t make sense for annotated array elements)

  • we allow per context custom value extractors

  • we allow value extractors to be contributed using the service loader mechanism

  • we allow to specify value extractors using XML configuration

  • we explore the parent classes and interfaces to search the ValueExtractor definition

Support for the new constraints added to Bean Validation 2.0

In the Alpha2 release of Bean Validation 2.0, we introduced the following new constraints:

  • @NotBlank: check that a char sequence is not blank (i.e. not null, and length of trimmed char sequence > 0)

  • @NotEmpty: check that an element (char sequence, collection, array) is not null and not empty

  • @Email: check that a char sequence is a valid email

  • @Positive: check that a number is positive

  • @Negative: check that a number is negative

We added support for these new constraints to Hibernate Validator.

Performance improvements

We started to run a few benchmarks on Hibernate Validator 6 and we fixed a few performance regressions.

6.0.0.Alpha2 is now significantly faster than 5.4, mostly thanks to the new ValueExtractor design.

Getting 6.0.0.Alpha2

To get the release with Maven, Gradle etc. use the GAV coordinates org.hibernate.validator:{hibernate-validator|hibernate-validator-cdi|hibernate-validator-annotation-processor}:6.0.0.Alpha2. Note that the group id has changed from org.hibernate (Hibernate Validator 5 and earlier) to org.hibernate.validator (from Hibernate Validator 6 onwards).

Alternatively, a distribution bundle containing all the bits is provided on SourceForge (TAR.GZ, ZIP).

Feedback, issues, ideas?

To get in touch, use the usual channels:

What’s next?

Bean Validation 2.0 and Hibernate Validator 6 are still under active development. We will release new alphas on a regular basis.

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