1/* 2 * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25package com.sun.beans.decoder; 26 27/** 28 * This class is intended to handle <null> element. 29 * This element specifies {@code null} value. 30 * It should not contain body or inner elements. 31 * For example:<pre> 32 * <null/></pre> 33 * is equivalent to {@code null} in Java code. 34 * <p>The following attribute is supported: 35 * <dl> 36 * <dt>id 37 * <dd>the identifier of the variable that is intended to store the result 38 * </dl> 39 * 40 * @since 1.7 41 * 42 * @author Sergey A. Malenkov 43 */ 44class NullElementHandler extends ElementHandler implements ValueObject { 45 46 /** 47 * Returns the value of this element. 48 * 49 * @return the value of this element 50 */ 51 @Override 52 protected final ValueObject getValueObject() { 53 return this; 54 } 55 56 /** 57 * Returns {@code null} 58 * as a value of <null> element. 59 * This method should be overridden in those handlers 60 * that extend behavior of this element. 61 * 62 * @return {@code null} by default 63 */ 64 public Object getValue() { 65 return null; 66 } 67 68 /** 69 * Returns {@code void} state of this value object. 70 * 71 * @return {@code false} always 72 */ 73 public final boolean isVoid() { 74 return false; 75 } 76} 77