Hibernate MappingException

I'm getting this Hibernate error:

org.hibernate.MappingException: Could not determine type for: 
a.b.c.Results$BusinessDate, for columns: [org.hibernate.mapping.Column(businessDate)]

The class is below. Does anyone know why I'm getting this error??

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = {
    "businessDate"
})
@XmlRootElement(name = "Results")
@Entity(name = "Results")
@Table(name = "RESULT")
@Inheritance(strategy = InheritanceType.JOINED)
@Cache(usage = CacheConcurrencyStrategy.READ_ONLY)
public class Results implements Equals, HashCode
{

    @XmlElement(name = "BusinessDate", required = true)
    protected Results.BusinessDate businessDate;

    public Results.BusinessDate getBusinessDate() {
        return businessDate;
    }

    public void setBusinessDate(Results.BusinessDate value) {
        this.businessDate = value;
    }

    @XmlAccessorType(XmlAccessType.FIELD)
    @XmlType(name = "", propOrder = {
        "raw",
        "display"
    })
    @Entity(name = "Results$BusinessDate")
    @Table(name = "BUSINESSDATE")
    @Inheritance(strategy = InheritanceType.JOINED)
    public static class BusinessDate implements Equals, HashCode
    {

    ....

Update: This code was generated by HyperJaxB. So I don't claim to understand it all, just trying to make some changes to it!

Update2: Here's the full (yah it's big) src file

Solution

Using a static nested class as a field type is fine and supported. But Hibernate won't know how to map such a complex type to a column type (which is what the error message says). So you'll need either to create a user type to handle this or to annotate the Results.BusinessDate field with a @OneToOne annotation to persist it in another table (I would also remove the @Inheritance which is useless but this is not the problem here).

Update: Just to clarify, using a user type or mapping the complex type with @OneToOne does work. The following code works perfectly (tested):

@Entity
public class EntityWithStaticNestedClass implements Serializable {
    @Id
    @GeneratedValue
    private Long id;

    @OneToOne
    private EntityWithStaticNestedClass.StaticNestedClass nested;

    public Long getId() { return id; }

    public void setId(Long id) { this.id = id; }

    public EntityWithStaticNestedClass.StaticNestedClass getNested() { 
        return nested;
    }

    public void setNested(EntityWithStaticNestedClass.StaticNestedClass nested) {
        this.nested = nested;
    }

    @Entity
    public static class StaticNestedClass implements Serializable {
        @Id
        @GeneratedValue
        private Long id;

        public Long getId() { return id; }

        public void setId(Long id) { this.id = id; }
    }
}

And both entities get well persisted in their respective tables. But you're not showing the entire code nor the exact error so I can't say why it didn't for you (maybe you're missing @Id etc).

That being said, if you don't want businessDate to be persisted at all, annotate it with @Transient (with JPA, fields are persistent by default):

Update: You can't mix field and property access. So you need to annotate getBusinessDate() with @Transienthere. Sorry, I couldn't guess that from the shown code and I thought it would be obvious.