1.1 --- a/emul/compact/src/main/java/java/util/Queue.java Mon Feb 25 19:00:08 2013 +0100
1.2 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000
1.3 @@ -1,218 +0,0 @@
1.4 -/*
1.5 - * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.6 - *
1.7 - * This code is free software; you can redistribute it and/or modify it
1.8 - * under the terms of the GNU General Public License version 2 only, as
1.9 - * published by the Free Software Foundation. Oracle designates this
1.10 - * particular file as subject to the "Classpath" exception as provided
1.11 - * by Oracle in the LICENSE file that accompanied this code.
1.12 - *
1.13 - * This code is distributed in the hope that it will be useful, but WITHOUT
1.14 - * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.15 - * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.16 - * version 2 for more details (a copy is included in the LICENSE file that
1.17 - * accompanied this code).
1.18 - *
1.19 - * You should have received a copy of the GNU General Public License version
1.20 - * 2 along with this work; if not, write to the Free Software Foundation,
1.21 - * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.22 - *
1.23 - * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.24 - * or visit www.oracle.com if you need additional information or have any
1.25 - * questions.
1.26 - */
1.27 -
1.28 -/*
1.29 - * This file is available under and governed by the GNU General Public
1.30 - * License version 2 only, as published by the Free Software Foundation.
1.31 - * However, the following notice accompanied the original version of this
1.32 - * file:
1.33 - *
1.34 - * Written by Doug Lea with assistance from members of JCP JSR-166
1.35 - * Expert Group and released to the public domain, as explained at
1.36 - * http://creativecommons.org/publicdomain/zero/1.0/
1.37 - */
1.38 -
1.39 -package java.util;
1.40 -
1.41 -/**
1.42 - * A collection designed for holding elements prior to processing.
1.43 - * Besides basic {@link java.util.Collection Collection} operations,
1.44 - * queues provide additional insertion, extraction, and inspection
1.45 - * operations. Each of these methods exists in two forms: one throws
1.46 - * an exception if the operation fails, the other returns a special
1.47 - * value (either <tt>null</tt> or <tt>false</tt>, depending on the
1.48 - * operation). The latter form of the insert operation is designed
1.49 - * specifically for use with capacity-restricted <tt>Queue</tt>
1.50 - * implementations; in most implementations, insert operations cannot
1.51 - * fail.
1.52 - *
1.53 - * <p>
1.54 - * <table BORDER CELLPADDING=3 CELLSPACING=1>
1.55 - * <tr>
1.56 - * <td></td>
1.57 - * <td ALIGN=CENTER><em>Throws exception</em></td>
1.58 - * <td ALIGN=CENTER><em>Returns special value</em></td>
1.59 - * </tr>
1.60 - * <tr>
1.61 - * <td><b>Insert</b></td>
1.62 - * <td>{@link #add add(e)}</td>
1.63 - * <td>{@link #offer offer(e)}</td>
1.64 - * </tr>
1.65 - * <tr>
1.66 - * <td><b>Remove</b></td>
1.67 - * <td>{@link #remove remove()}</td>
1.68 - * <td>{@link #poll poll()}</td>
1.69 - * </tr>
1.70 - * <tr>
1.71 - * <td><b>Examine</b></td>
1.72 - * <td>{@link #element element()}</td>
1.73 - * <td>{@link #peek peek()}</td>
1.74 - * </tr>
1.75 - * </table>
1.76 - *
1.77 - * <p>Queues typically, but do not necessarily, order elements in a
1.78 - * FIFO (first-in-first-out) manner. Among the exceptions are
1.79 - * priority queues, which order elements according to a supplied
1.80 - * comparator, or the elements' natural ordering, and LIFO queues (or
1.81 - * stacks) which order the elements LIFO (last-in-first-out).
1.82 - * Whatever the ordering used, the <em>head</em> of the queue is that
1.83 - * element which would be removed by a call to {@link #remove() } or
1.84 - * {@link #poll()}. In a FIFO queue, all new elements are inserted at
1.85 - * the <em> tail</em> of the queue. Other kinds of queues may use
1.86 - * different placement rules. Every <tt>Queue</tt> implementation
1.87 - * must specify its ordering properties.
1.88 - *
1.89 - * <p>The {@link #offer offer} method inserts an element if possible,
1.90 - * otherwise returning <tt>false</tt>. This differs from the {@link
1.91 - * java.util.Collection#add Collection.add} method, which can fail to
1.92 - * add an element only by throwing an unchecked exception. The
1.93 - * <tt>offer</tt> method is designed for use when failure is a normal,
1.94 - * rather than exceptional occurrence, for example, in fixed-capacity
1.95 - * (or "bounded") queues.
1.96 - *
1.97 - * <p>The {@link #remove()} and {@link #poll()} methods remove and
1.98 - * return the head of the queue.
1.99 - * Exactly which element is removed from the queue is a
1.100 - * function of the queue's ordering policy, which differs from
1.101 - * implementation to implementation. The <tt>remove()</tt> and
1.102 - * <tt>poll()</tt> methods differ only in their behavior when the
1.103 - * queue is empty: the <tt>remove()</tt> method throws an exception,
1.104 - * while the <tt>poll()</tt> method returns <tt>null</tt>.
1.105 - *
1.106 - * <p>The {@link #element()} and {@link #peek()} methods return, but do
1.107 - * not remove, the head of the queue.
1.108 - *
1.109 - * <p>The <tt>Queue</tt> interface does not define the <i>blocking queue
1.110 - * methods</i>, which are common in concurrent programming. These methods,
1.111 - * which wait for elements to appear or for space to become available, are
1.112 - * defined in the {@link java.util.concurrent.BlockingQueue} interface, which
1.113 - * extends this interface.
1.114 - *
1.115 - * <p><tt>Queue</tt> implementations generally do not allow insertion
1.116 - * of <tt>null</tt> elements, although some implementations, such as
1.117 - * {@link LinkedList}, do not prohibit insertion of <tt>null</tt>.
1.118 - * Even in the implementations that permit it, <tt>null</tt> should
1.119 - * not be inserted into a <tt>Queue</tt>, as <tt>null</tt> is also
1.120 - * used as a special return value by the <tt>poll</tt> method to
1.121 - * indicate that the queue contains no elements.
1.122 - *
1.123 - * <p><tt>Queue</tt> implementations generally do not define
1.124 - * element-based versions of methods <tt>equals</tt> and
1.125 - * <tt>hashCode</tt> but instead inherit the identity based versions
1.126 - * from class <tt>Object</tt>, because element-based equality is not
1.127 - * always well-defined for queues with the same elements but different
1.128 - * ordering properties.
1.129 - *
1.130 - *
1.131 - * <p>This interface is a member of the
1.132 - * <a href="{@docRoot}/../technotes/guides/collections/index.html">
1.133 - * Java Collections Framework</a>.
1.134 - *
1.135 - * @see java.util.Collection
1.136 - * @see LinkedList
1.137 - * @see PriorityQueue
1.138 - * @see java.util.concurrent.LinkedBlockingQueue
1.139 - * @see java.util.concurrent.BlockingQueue
1.140 - * @see java.util.concurrent.ArrayBlockingQueue
1.141 - * @see java.util.concurrent.LinkedBlockingQueue
1.142 - * @see java.util.concurrent.PriorityBlockingQueue
1.143 - * @since 1.5
1.144 - * @author Doug Lea
1.145 - * @param <E> the type of elements held in this collection
1.146 - */
1.147 -public interface Queue<E> extends Collection<E> {
1.148 - /**
1.149 - * Inserts the specified element into this queue if it is possible to do so
1.150 - * immediately without violating capacity restrictions, returning
1.151 - * <tt>true</tt> upon success and throwing an <tt>IllegalStateException</tt>
1.152 - * if no space is currently available.
1.153 - *
1.154 - * @param e the element to add
1.155 - * @return <tt>true</tt> (as specified by {@link Collection#add})
1.156 - * @throws IllegalStateException if the element cannot be added at this
1.157 - * time due to capacity restrictions
1.158 - * @throws ClassCastException if the class of the specified element
1.159 - * prevents it from being added to this queue
1.160 - * @throws NullPointerException if the specified element is null and
1.161 - * this queue does not permit null elements
1.162 - * @throws IllegalArgumentException if some property of this element
1.163 - * prevents it from being added to this queue
1.164 - */
1.165 - boolean add(E e);
1.166 -
1.167 - /**
1.168 - * Inserts the specified element into this queue if it is possible to do
1.169 - * so immediately without violating capacity restrictions.
1.170 - * When using a capacity-restricted queue, this method is generally
1.171 - * preferable to {@link #add}, which can fail to insert an element only
1.172 - * by throwing an exception.
1.173 - *
1.174 - * @param e the element to add
1.175 - * @return <tt>true</tt> if the element was added to this queue, else
1.176 - * <tt>false</tt>
1.177 - * @throws ClassCastException if the class of the specified element
1.178 - * prevents it from being added to this queue
1.179 - * @throws NullPointerException if the specified element is null and
1.180 - * this queue does not permit null elements
1.181 - * @throws IllegalArgumentException if some property of this element
1.182 - * prevents it from being added to this queue
1.183 - */
1.184 - boolean offer(E e);
1.185 -
1.186 - /**
1.187 - * Retrieves and removes the head of this queue. This method differs
1.188 - * from {@link #poll poll} only in that it throws an exception if this
1.189 - * queue is empty.
1.190 - *
1.191 - * @return the head of this queue
1.192 - * @throws NoSuchElementException if this queue is empty
1.193 - */
1.194 - E remove();
1.195 -
1.196 - /**
1.197 - * Retrieves and removes the head of this queue,
1.198 - * or returns <tt>null</tt> if this queue is empty.
1.199 - *
1.200 - * @return the head of this queue, or <tt>null</tt> if this queue is empty
1.201 - */
1.202 - E poll();
1.203 -
1.204 - /**
1.205 - * Retrieves, but does not remove, the head of this queue. This method
1.206 - * differs from {@link #peek peek} only in that it throws an exception
1.207 - * if this queue is empty.
1.208 - *
1.209 - * @return the head of this queue
1.210 - * @throws NoSuchElementException if this queue is empty
1.211 - */
1.212 - E element();
1.213 -
1.214 - /**
1.215 - * Retrieves, but does not remove, the head of this queue,
1.216 - * or returns <tt>null</tt> if this queue is empty.
1.217 - *
1.218 - * @return the head of this queue, or <tt>null</tt> if this queue is empty
1.219 - */
1.220 - E peek();
1.221 -}