001/*
002 * Copyright (c) 2008, 2009, 2011 Oracle, Inc. All rights reserved.
003 *
004 * This program and the accompanying materials are made available under the
005 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
006 * which accompanies this distribution.  The Eclipse Public License is available
007 * at http://www.eclipse.org/legal/epl-v10.html and the Eclipse Distribution License
008 * is available at http://www.eclipse.org/org/documents/edl-v10.php.
009 */
010package javax.persistence;
011
012import java.lang.annotation.Retention;
013import java.lang.annotation.Target;
014
015import static java.lang.annotation.ElementType.FIELD;
016import static java.lang.annotation.RetentionPolicy.RUNTIME;
017import static javax.persistence.FetchType.LAZY;
018
019/**
020 * Defines a collection of instances of a basic type or embeddable class. Must be specified if the collection
021 * is to be mapped by means of a collection table.
022 * <p>
023 * <pre>
024 *    Example:
025 *
026 *    &#064;Entity public class Person {
027 *       &#064;Id protected String ssn;
028 *       protected String name;
029 *       ...
030 *       &#064;ElementCollection
031 *       protected Set&#060;String&#062; nickNames = new HashSet();
032 *         ...
033 *    }
034 * </pre>
035 *
036 * @since Java Persistence 2.0
037 */
038@Target({FIELD})
039@Retention(RUNTIME)
040public @interface ElementCollection {
041
042  /**
043   * (Optional) The basic or embeddable class that is the element type of the collection. This element is
044   * optional only if the collection field or property is defined using Java generics, and must be specified
045   * otherwise. It defaults to the paramterized type of the collection when defined using generics.
046   *
047   * @return target class
048   */
049  Class targetClass() default void.class;
050
051  /**
052   * (Optional) Whether the collection should be lazily loaded or must be eagerly fetched. The EAGER
053   * strategy is a requirement on the persistence provider runtime that the collection elements must be
054   * eagerly fetched. The LAZY strategy is a hint to the persistence provider runtime.
055   *
056   * @return fetch type
057   */
058  FetchType fetch() default LAZY;
059}