1 /* 2 * Copyright 2001-2004 The Apache Software Foundation 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 package org.apache.commons.cache.adt; 17 18 /** 19 * An base implementation of {@link Listable}, supporting 20 * doubly-linked lists. 21 * 22 * @version $Id: WListableBase.java 155435 2005-02-26 13:17:27Z dirkv $ 23 * @author Rodney Waldhoff 24 */ 25 public class WListableBase extends ListableBase implements Listable, Cloneable { 26 27 /** My preceeding sibling. */ 28 protected transient Listable _prev = null; 29 30 /** 31 * No arg constructor. 32 * Equivalent to {@link #WListableBase(Listable,Listable) <tt>WListableBase(null,null)</tt>}. 33 */ 34 public WListableBase() { 35 } 36 37 /** 38 * Constructor. 39 * @param prev the prev element in the list. 40 * @param next the next element in the list. 41 */ 42 public WListableBase(Listable prev, Listable next) { 43 super(next); 44 _prev = prev; 45 } 46 47 public Listable getPrev() { 48 return _prev; 49 } 50 51 public boolean hasPrev() { 52 return (null != _prev); 53 } 54 55 public void setPrev(Listable prev) { 56 _prev = prev; 57 } 58 }