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.METHOD; import static java.lang.annotation.ElementType.FIELD; import static java.lang.annotation.RetentionPolicy.RUNTIME; /** * Specifies the version field or property of an entity class that * serves as its optimistic lock value. The version is used to ensure * integrity when performing the merge operation and for optimistic * concurrency control. * * <p> Only a single <code>Version</code> property or field * should be used per class; applications that use more than one * <code>Version</code> property or field will not be portable. * * <p> The <code>Version</code> property should be mapped to * the primary table for the entity class; applications that * map the <code>Version</code> property to a table other than * the primary table will not be portable. * * <p> The following types are supported for version properties: * <code>int</code>, <code>Integer</code>, <code>short</code>, * <code>Short</code>, <code>long</code>, <code>Long</code>, * <code>java.sql.Timestamp</code>. * * <pre> * Example: * * @Version * @Column(name="OPTLOCK") * protected int getVersionNum() { return versionNum; } * </pre> * * @since Java Persistence 1.0 */ @Target({ METHOD, FIELD }) @Retention(RUNTIME) public @interface Version { }