Copyright (c) 2008 - 2013 Oracle Corporation. All rights reserved.
This program and the accompanying materials are made available under the
terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
which accompanies this distribution.
The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
and the Eclipse Distribution License is available at
http://www.eclipse.org/org/documents/edl-v10.php.
Contributors:
    Linda DeMichiel - Java Persistence 2.1
    Linda DeMichiel - Java Persistence 2.0
/*******************************************************************************
 * Copyright (c) 2008 - 2013 Oracle Corporation. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Linda DeMichiel - Java Persistence 2.1
 *     Linda DeMichiel - Java Persistence 2.0
 *
 ******************************************************************************/ 
package javax.persistence;

import java.lang.annotation.Target;
import java.lang.annotation.Retention;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import static javax.persistence.EnumType.ORDINAL;

Specifies the enum type for a map key whose basic type is an enumerated type.
The MapKeyEnumerated annotation can be applied to an 
element collection or relationship of type java.util.Map, in 
conjunction with the ElementCollection, OneToMany, or 
ManyToMany annotation.
If the enumerated type is not specified or the MapKeyEnumerated
annotation is not used, the enumerated type is assumed to be
ORDINAL.
  Example:
  public enum ProjectStatus {COMPLETE, DELAYED, CANCELLED, IN_PROGRESS}
  public enum SalaryRate {JUNIOR, SENIOR, MANAGER, EXECUTIVE}
  @Entity public class Employee {
      @ManyToMany
      public Projects<ProjectStatus, Project> getProjects() {...}
      
      @OneToMany
      @MapKeyEnumerated(STRING)
      public Map<SalaryRate, Employee> getEmployees() {...}
      ...
  }

See Also:
ElementCollection
OneToMany
ManyToMany
Since:
Java Persistence 2.0/**
 * Specifies the enum type for a map key whose basic type is an enumerated type.
 * 
 * The <code>MapKeyEnumerated</code> annotation can be applied to an 
 * element collection or relationship of type <code>java.util.Map</code>, in 
 * conjunction with the <code>ElementCollection</code>, <code>OneToMany</code>, or 
 * <code>ManyToMany</code> annotation.
 * If the enumerated type is not specified or the <code>MapKeyEnumerated</code>
 * annotation is not used, the enumerated type is assumed to be
 * <code>ORDINAL</code>.
 *
 * <pre>
 *   Example:
 *
 *   public enum ProjectStatus {COMPLETE, DELAYED, CANCELLED, IN_PROGRESS}
 *
 *   public enum SalaryRate {JUNIOR, SENIOR, MANAGER, EXECUTIVE}
 *
 *   &#064;Entity public class Employee {
 *       &#064;ManyToMany
 *       public Projects&#060;ProjectStatus, Project&#062; getProjects() {...}
 *       
 *       &#064;OneToMany
 *       &#064;MapKeyEnumerated(STRING)
 *       public Map&#060;SalaryRate, Employee&#062; getEmployees() {...}
 *       ...
 *   }
 * </pre>
 *
 * @see ElementCollection
 * @see OneToMany
 * @see ManyToMany
 *
 * @since Java Persistence 2.0
 */
@Target({METHOD, FIELD}) @Retention(RUNTIME)
public @interface MapKeyEnumerated {
    
    
(Optional) The type used in mapping a map key enum type. /** (Optional) The type used in mapping a map key enum type. */
    EnumType value() default ORDINAL;
}