src/javax/persistence/MapKeyEnumerated.java

/*
 * Copyright (c) 2008, 2018 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0,
 * or the Eclipse Distribution License v. 1.0 which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
 */

// 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 <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. */
    EnumType value() default ORDINAL;
}