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My first initial commit with all of mine experimental changes.

Dmitry Kabak (userdima committed 13 years ago

Commit d37b88d1 parent 3f5b46618352 files · +2598093 −-8690Browse files

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1+/*
2+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3+ *
4+ * This code is free software; you can redistribute it and/or modify it
5+ * under the terms of the GNU General Public License version 2 only, as
6+ * published by the Free Software Foundation. Oracle designates this
7+ * particular file as subject to the "Classpath" exception as provided
8+ * by Oracle in the LICENSE file that accompanied this code.
9+ *
10+ * This code is distributed in the hope that it will be useful, but WITHOUT
11+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13+ * version 2 for more details (a copy is included in the LICENSE file that
14+ * accompanied this code).
15+ *
16+ * You should have received a copy of the GNU General Public License version
17+ * 2 along with this work; if not, write to the Free Software Foundation,
18+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19+ *
20+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21+ * or visit www.oracle.com if you need additional information or have any
22+ * questions.
23+ */
24+
25+/*
26+ * This file is available under and governed by the GNU General Public
27+ * License version 2 only, as published by the Free Software Foundation.
28+ * However, the following notice accompanied the original version of this
29+ * file:
30+ *
31+ * Written by Doug Lea with assistance from members of JCP JSR-166
32+ * Expert Group and released to the public domain, as explained at
33+ * http://creativecommons.org/publicdomain/zero/1.0/
34+ */
35+
36+package java.util;
37+
38+/**
39+ * A collection designed for holding elements prior to processing.
40+ * Besides basic {@link java.util.Collection Collection} operations,
41+ * queues provide additional insertion, extraction, and inspection
42+ * operations. Each of these methods exists in two forms: one throws
43+ * an exception if the operation fails, the other returns a special
44+ * value (either <tt>null</tt> or <tt>false</tt>, depending on the
45+ * operation). The latter form of the insert operation is designed
46+ * specifically for use with capacity-restricted <tt>Queue</tt>
47+ * implementations; in most implementations, insert operations cannot
48+ * fail.
49+ *
50+ * <p>
51+ * <table BORDER CELLPADDING=3 CELLSPACING=1>
52+ * <tr>
53+ * <td></td>
54+ * <td ALIGN=CENTER><em>Throws exception</em></td>
55+ * <td ALIGN=CENTER><em>Returns special value</em></td>
56+ * </tr>
57+ * <tr>
58+ * <td><b>Insert</b></td>
59+ * <td>{@link #add add(e)}</td>
60+ * <td>{@link #offer offer(e)}</td>
61+ * </tr>
62+ * <tr>
63+ * <td><b>Remove</b></td>
64+ * <td>{@link #remove remove()}</td>
65+ * <td>{@link #poll poll()}</td>
66+ * </tr>
67+ * <tr>
68+ * <td><b>Examine</b></td>
69+ * <td>{@link #element element()}</td>
70+ * <td>{@link #peek peek()}</td>
71+ * </tr>
72+ * </table>
73+ *
74+ * <p>Queues typically, but do not necessarily, order elements in a
75+ * FIFO (first-in-first-out) manner. Among the exceptions are
76+ * priority queues, which order elements according to a supplied
77+ * comparator, or the elements' natural ordering, and LIFO queues (or
78+ * stacks) which order the elements LIFO (last-in-first-out).
79+ * Whatever the ordering used, the <em>head</em> of the queue is that
80+ * element which would be removed by a call to {@link #remove() } or
81+ * {@link #poll()}. In a FIFO queue, all new elements are inserted at
82+ * the <em> tail</em> of the queue. Other kinds of queues may use
83+ * different placement rules. Every <tt>Queue</tt> implementation
84+ * must specify its ordering properties.
85+ *
86+ * <p>The {@link #offer offer} method inserts an element if possible,
87+ * otherwise returning <tt>false</tt>. This differs from the {@link
88+ * java.util.Collection#add Collection.add} method, which can fail to
89+ * add an element only by throwing an unchecked exception. The
90+ * <tt>offer</tt> method is designed for use when failure is a normal,
91+ * rather than exceptional occurrence, for example, in fixed-capacity
92+ * (or &quot;bounded&quot;) queues.
93+ *
94+ * <p>The {@link #remove()} and {@link #poll()} methods remove and
95+ * return the head of the queue.
96+ * Exactly which element is removed from the queue is a
97+ * function of the queue's ordering policy, which differs from
98+ * implementation to implementation. The <tt>remove()</tt> and
99+ * <tt>poll()</tt> methods differ only in their behavior when the
100+ * queue is empty: the <tt>remove()</tt> method throws an exception,
101+ * while the <tt>poll()</tt> method returns <tt>null</tt>.
102+ *
103+ * <p>The {@link #element()} and {@link #peek()} methods return, but do
104+ * not remove, the head of the queue.
105+ *
106+ * <p>The <tt>Queue</tt> interface does not define the <i>blocking queue
107+ * methods</i>, which are common in concurrent programming. These methods,
108+ * which wait for elements to appear or for space to become available, are
109+ * defined in the {@link java.util.concurrent.BlockingQueue} interface, which
110+ * extends this interface.
111+ *
112+ * <p><tt>Queue</tt> implementations generally do not allow insertion
113+ * of <tt>null</tt> elements, although some implementations, such as
114+ * {@link LinkedList}, do not prohibit insertion of <tt>null</tt>.
115+ * Even in the implementations that permit it, <tt>null</tt> should
116+ * not be inserted into a <tt>Queue</tt>, as <tt>null</tt> is also
117+ * used as a special return value by the <tt>poll</tt> method to
118+ * indicate that the queue contains no elements.
119+ *
120+ * <p><tt>Queue</tt> implementations generally do not define
121+ * element-based versions of methods <tt>equals</tt> and
122+ * <tt>hashCode</tt> but instead inherit the identity based versions
123+ * from class <tt>Object</tt>, because element-based equality is not
124+ * always well-defined for queues with the same elements but different
125+ * ordering properties.
126+ *
127+ *
128+ * <p>This interface is a member of the
129+ * <a href="{@docRoot}/../technotes/guides/collections/index.html">
130+ * Java Collections Framework</a>.
131+ *
132+ * @see java.util.Collection
133+ * @see LinkedList
134+ * @see PriorityQueue
135+ * @see java.util.concurrent.LinkedBlockingQueue
136+ * @see java.util.concurrent.BlockingQueue
137+ * @see java.util.concurrent.ArrayBlockingQueue
138+ * @see java.util.concurrent.LinkedBlockingQueue
139+ * @see java.util.concurrent.PriorityBlockingQueue
140+ * @since 1.5
141+ * @author Doug Lea
142+ * @param <E> the type of elements held in this collection
143+ */
144+public interface Queue<E> extends Collection<E> {
145+ /**
146+ * Inserts the specified element into this queue if it is possible to do so
147+ * immediately without violating capacity restrictions, returning
148+ * <tt>true</tt> upon success and throwing an <tt>IllegalStateException</tt>
149+ * if no space is currently available.
150+ *
151+ * @param e the element to add
152+ * @return <tt>true</tt> (as specified by {@link Collection#add})
153+ * @throws IllegalStateException if the element cannot be added at this
154+ * time due to capacity restrictions
155+ * @throws ClassCastException if the class of the specified element
156+ * prevents it from being added to this queue
157+ * @throws NullPointerException if the specified element is null and
158+ * this queue does not permit null elements
159+ * @throws IllegalArgumentException if some property of this element
160+ * prevents it from being added to this queue
161+ */
162+ boolean add(E e);
163+
164+ /**
165+ * Inserts the specified element into this queue if it is possible to do
166+ * so immediately without violating capacity restrictions.
167+ * When using a capacity-restricted queue, this method is generally
168+ * preferable to {@link #add}, which can fail to insert an element only
169+ * by throwing an exception.
170+ *
171+ * @param e the element to add
172+ * @return <tt>true</tt> if the element was added to this queue, else
173+ * <tt>false</tt>
174+ * @throws ClassCastException if the class of the specified element
175+ * prevents it from being added to this queue
176+ * @throws NullPointerException if the specified element is null and
177+ * this queue does not permit null elements
178+ * @throws IllegalArgumentException if some property of this element
179+ * prevents it from being added to this queue
180+ */
181+ boolean offer(E e);
182+
183+ /**
184+ * Retrieves and removes the head of this queue. This method differs
185+ * from {@link #poll poll} only in that it throws an exception if this
186+ * queue is empty.
187+ *
188+ * @return the head of this queue
189+ * @throws NoSuchElementException if this queue is empty
190+ */
191+ E remove();
192+
193+ /**
194+ * Retrieves and removes the head of this queue,
195+ * or returns <tt>null</tt> if this queue is empty.
196+ *
197+ * @return the head of this queue, or <tt>null</tt> if this queue is empty
198+ */
199+ E poll();
200+
201+ /**
202+ * Retrieves, but does not remove, the head of this queue. This method
203+ * differs from {@link #peek peek} only in that it throws an exception
204+ * if this queue is empty.
205+ *
206+ * @return the head of this queue
207+ * @throws NoSuchElementException if this queue is empty
208+ */
209+ E element();
210+
211+ /**
212+ * Retrieves, but does not remove, the head of this queue,
213+ * or returns <tt>null</tt> if this queue is empty.
214+ *
215+ * @return the head of this queue, or <tt>null</tt> if this queue is empty
216+ */
217+ E peek();
218+}