Java tutorial
/******************************************************************************* * 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; /** * Specifies the primary key of an entity. * The field or property to which the <code>Id</code> annotation is applied * should be one of the following types: any Java primitive type; * any primitive wrapper type; * <code>String</code>; * <code>java.util.Date</code>; * <code>java.sql.Date</code>; * <code>java.math.BigDecimal</code>; * <code>java.math.BigInteger</code>. * * <p>The mapped column for the primary key of the entity is assumed * to be the primary key of the primary table. If no <code>Column</code> annotation * is specified, the primary key column name is assumed to be the name * of the primary key property or field. * * <pre> * Example: * * @Id * public Long getId() { return id; } * </pre> * * @see Column * @see GeneratedValue * * @since Java Persistence 1.0 */ @Target({ METHOD, FIELD }) @Retention(RUNTIME) public @interface Id { }