001    /**
002     * Copyright (c) 2000-2010 Liferay, Inc. All rights reserved.
003     *
004     * This library is free software; you can redistribute it and/or modify it under
005     * the terms of the GNU Lesser General Public License as published by the Free
006     * Software Foundation; either version 2.1 of the License, or (at your option)
007     * any later version.
008     *
009     * This library is distributed in the hope that it will be useful, but WITHOUT
010     * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
011     * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
012     * details.
013     */
014    
015    package com.liferay.util;
016    
017    /**
018     * @author Brian Wing Shun Chan
019     */
020    public class FiniteUniqueStack<E> extends FiniteStack<E> {
021    
022            public FiniteUniqueStack(int maxSize) {
023                    super(maxSize);
024            }
025    
026            public E push(E item) {
027                    if (!contains(item)) {
028                            super.push(item);
029                    }
030                    else {
031                            if (!item.equals(peek())) {
032                                    remove(item);
033                                    super.push(item);
034                            }
035                    }
036    
037                    return item;
038            }
039    
040    }