Java tutorial
/* * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. * * Copyright (c) 1997-2010 Oracle and/or its affiliates. All rights reserved. * * The contents of this file are subject to the terms of either the GNU * General Public License Version 2 only ("GPL") or the Common Development * and Distribution License("CDDL") (collectively, the "License"). You * may not use this file except in compliance with the License. You can * obtain a copy of the License at * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html * or packager/legal/LICENSE.txt. See the License for the specific * language governing permissions and limitations under the License. * * When distributing the software, include this License Header Notice in each * file and include the License file at packager/legal/LICENSE.txt. * * GPL Classpath Exception: * Oracle designates this particular file as subject to the "Classpath" * exception as provided by Oracle in the GPL Version 2 section of the License * file that accompanied this code. * * Modifications: * If applicable, add the following below the License Header, with the fields * enclosed by brackets [] replaced by your own identifying information: * "Portions Copyright [year] [name of copyright owner]" * * Contributor(s): * If you wish your version of this file to be governed by only the CDDL or * only the GPL Version 2, indicate your decision by adding "[Contributor] * elects to include this software in this distribution under the [CDDL or GPL * Version 2] license." If you don't indicate a single choice of license, a * recipient has the option to distribute your version of this file under * either the CDDL, the GPL Version 2 or to extend the choice of license to * its licensees as provided above. However, if you add GPL Version 2 code * and therefore, elected the GPL Version 2 license, then the option applies * only if the new code is made subject to such option by the copyright * holder. * * * This file incorporates work covered by the following copyright and * permission notice: * * Copyright 2004 The Apache Software Foundation * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package javax.servlet.jsp.el; /** * <p>The abstract class for a prepared expression.</p> * * <p>An instance of an Expression can be obtained via from an * ExpressionEvaluator instance.</p> * * <p>An Expression may or not have done a syntactic parse of the expression. * A client invoking the evaluate() method should be ready for the case * where ELParseException exceptions are raised. </p> * * @deprecated As of JSP 2.1, replaced by {@link javax.el.ValueExpression} * @since JSP 2.0 */ public abstract class Expression { /** * Evaluates an expression that was previously prepared. In some * implementations preparing an expression involves full syntactic * validation, but others may not do so. Evaluating the expression may * raise an ELParseException as well as other ELExceptions due to * run-time evaluation. * * @param vResolver A VariableResolver instance that can be used at * runtime to resolve the name of implicit objects into Objects. * @return The result of the expression evaluation. * * @exception ELException Thrown if the expression evaluation failed. */ public abstract Object evaluate(VariableResolver vResolver) throws ELException; }