@Target(value={METHOD,FIELD}) @Retention(value=RUNTIME) public @interface MapKeyClass
java.util.Map
. The map key can be a
basic type, an embeddable class, or an entity. If the map is specified using Java generics, the
MapKeyClass
annotation and associated type need not be specified; otherwise they must be
specified.
The MapKeyClass
annotation is used in conjunction with ElementCollection
or one
of the collection-valued relationship annotations (OneToMany
or ManyToMany
). The
MapKey
annotation is not used when MapKeyClass
is specified and vice versa.
Example 1: @Entity public class Item { @Id int id; ... @ElementCollection(targetClass=String.class) @MapKeyClass(String.class) Map images; // map from image name to image filename ... } Example 2: // MapKeyClass and target type of relationship can be defaulted @Entity public class Item { @Id int id; ... @ElementCollection Map<String, String> images; ... } Example 3: @Entity public class Company { @Id int id; ... @OneToMany(targetEntity=com.example.VicePresident.class) @MapKeyClass(com.example.Division.class) Map organization; } Example 4: // MapKeyClass and target type of relationship are defaulted @Entity public class Company { @Id int id; ... @OneToMany Map<Division, VicePresident> organization; }
ElementCollection
,
OneToMany
,
ManyToMany
public abstract Class value
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