001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.commons.collections; 018 019 /** 020 * Defines a collection for priority queues, which can insert, peek and pop. 021 * <p> 022 * This interface is now replaced by the <code>Buffer</code> interface. 023 * 024 * @deprecated Replaced by the Buffer interface and implementations in buffer subpackage. 025 * Due to be removed in v4.0. 026 * @since Commons Collections 1.0 027 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ 028 * 029 * @author Peter Donald 030 */ 031 public interface PriorityQueue { 032 033 /** 034 * Clear all elements from queue. 035 */ 036 void clear(); 037 038 /** 039 * Test if queue is empty. 040 * 041 * @return true if queue is empty else false. 042 */ 043 boolean isEmpty(); 044 045 /** 046 * Insert an element into queue. 047 * 048 * @param element the element to be inserted 049 * 050 * @throws ClassCastException if the specified <code>element</code>'s 051 * type prevents it from being compared to other items in the queue to 052 * determine its relative priority. 053 */ 054 void insert(Object element); 055 056 /** 057 * Return element on top of heap but don't remove it. 058 * 059 * @return the element at top of heap 060 * @throws java.util.NoSuchElementException if <code>isEmpty() == true</code> 061 */ 062 Object peek(); 063 064 /** 065 * Return element on top of heap and remove it. 066 * 067 * @return the element at top of heap 068 * @throws java.util.NoSuchElementException if <code>isEmpty() == true</code> 069 */ 070 Object pop(); 071 072 }