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| <div id="overview"><a href="../../../../../apidocs/org/apache/mina/util/Queue.html">View Javadoc</a></div><pre> |
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| <a name="1" href="#1">1</a> <em class="comment">/*</em>
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| <a name="2" href="#2">2</a> <em class="comment"> * @(#) $Id: Queue.java 210062 2005-07-11 03:52:38Z trustin $</em>
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| <a name="3" href="#3">3</a> <em class="comment"> *</em>
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| <a name="4" href="#4">4</a> <em class="comment"> * Copyright 2004 The Apache Software Foundation</em>
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| <a name="5" href="#5">5</a> <em class="comment"> *</em>
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| <a name="6" href="#6">6</a> <em class="comment"> * Licensed under the Apache License, Version 2.0 (the "License");</em>
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| <a name="7" href="#7">7</a> <em class="comment"> * you may not use this file except in compliance with the License.</em>
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| <a name="8" href="#8">8</a> <em class="comment"> * You may obtain a copy of the License at</em>
|
| <a name="9" href="#9">9</a> <em class="comment"> *</em>
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| <a name="10" href="#10">10</a> <em class="comment"> * <a href="http://www.apache.org/licenses/LICENSE-2.0" target="alexandria_uri">http://www.apache.org/licenses/LICENSE-2.0</a></em>
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| <a name="11" href="#11">11</a> <em class="comment"> *</em>
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| <a name="12" href="#12">12</a> <em class="comment"> * Unless required by applicable law or agreed to in writing, software</em>
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| <a name="13" href="#13">13</a> <em class="comment"> * distributed under the License is distributed on an "AS IS" BASIS,</em>
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| <a name="14" href="#14">14</a> <em class="comment"> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.</em>
|
| <a name="15" href="#15">15</a> <em class="comment"> * See the License for the specific language governing permissions and</em>
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| <a name="16" href="#16">16</a> <em class="comment"> * limitations under the License.</em>
|
| <a name="17" href="#17">17</a> <em class="comment"> *</em>
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| <a name="18" href="#18">18</a> <em class="comment"> */</em>
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| <a name="19" href="#19">19</a> <strong>package</strong> <a href="../../../../org/apache/mina/util/package-summary.html">org.apache.mina.util</a>;
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| <a name="20" href="#20">20</a>
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| <a name="21" href="#21">21</a> <strong>import</strong> java.io.Serializable;
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| <a name="22" href="#22">22</a> <strong>import</strong> java.util.Arrays;
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| <a name="23" href="#23">23</a>
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| <a name="24" href="#24">24</a> <em>/**<em>*</em></em>
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| <a name="25" href="#25">25</a> <em> * A unbounded circular queue.</em>
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| <a name="26" href="#26">26</a> <em> * </em>
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| <a name="27" href="#27">27</a> <em> * @author Trustin Lee (trustin@apache.org)</em>
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| <a name="28" href="#28">28</a> <em> * @version $Rev: 210062 $, $Date: 2005-07-11 12:52:38 +0900 $</em>
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| <a name="29" href="#29">29</a> <em> */</em>
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| <a name="30" href="#30">30</a> <strong>public</strong> <strong>class</strong> <a href="../../../../org/apache/mina/util/Queue.html">Queue</a> implements Serializable
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| <a name="31" href="#31">31</a> {
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| <a name="32" href="#32">32</a> <strong>private</strong> <strong>static</strong> <strong>final</strong> <strong>long</strong> serialVersionUID = 3835151744526464313L;
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| <a name="33" href="#33">33</a>
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| <a name="34" href="#34">34</a> <strong>private</strong> <strong>static</strong> <strong>final</strong> <strong>int</strong> DEFAULT_CAPACITY = 4;
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| <a name="35" href="#35">35</a>
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| <a name="36" href="#36">36</a> <strong>private</strong> <strong>static</strong> <strong>final</strong> <strong>int</strong> DEFAULT_MASK = DEFAULT_CAPACITY - 1;
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| <a name="37" href="#37">37</a>
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| <a name="38" href="#38">38</a> <strong>private</strong> Object[] items;
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| <a name="39" href="#39">39</a>
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| <a name="40" href="#40">40</a> <strong>private</strong> <strong>int</strong> mask;
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| <a name="41" href="#41">41</a>
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| <a name="42" href="#42">42</a> <strong>private</strong> <strong>int</strong> first = 0;
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| <a name="43" href="#43">43</a>
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| <a name="44" href="#44">44</a> <strong>private</strong> <strong>int</strong> last = 0;
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| <a name="45" href="#45">45</a>
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| <a name="46" href="#46">46</a> <strong>private</strong> <strong>int</strong> size = 0;
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| <a name="47" href="#47">47</a>
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| <a name="48" href="#48">48</a> <em>/**<em>*</em></em>
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| <a name="49" href="#49">49</a> <em> * Construct a new, empty queue.</em>
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| <a name="50" href="#50">50</a> <em> */</em>
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| <a name="51" href="#51">51</a> <strong>public</strong> <a href="../../../../org/apache/mina/util/Queue.html">Queue</a>()
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| <a name="52" href="#52">52</a> {
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| <a name="53" href="#53">53</a> items = <strong>new</strong> Object[ DEFAULT_CAPACITY ];
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| <a name="54" href="#54">54</a> mask = DEFAULT_MASK;
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| <a name="55" href="#55">55</a> }
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| <a name="56" href="#56">56</a>
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| <a name="57" href="#57">57</a> <em>/**<em>*</em></em>
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| <a name="58" href="#58">58</a> <em> * Returns the capacity of this queue.</em>
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| <a name="59" href="#59">59</a> <em> */</em>
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| <a name="60" href="#60">60</a> <strong>public</strong> <strong>int</strong> capacity()
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| <a name="61" href="#61">61</a> {
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| <a name="62" href="#62">62</a> <strong>return</strong> items.length;
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| <a name="63" href="#63">63</a> }
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| <a name="64" href="#64">64</a>
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| <a name="65" href="#65">65</a> <em>/**<em>*</em></em>
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| <a name="66" href="#66">66</a> <em> * Clears this queue.</em>
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| <a name="67" href="#67">67</a> <em> */</em>
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| <a name="68" href="#68">68</a> <strong>public</strong> <strong>void</strong> clear()
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| <a name="69" href="#69">69</a> {
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| <a name="70" href="#70">70</a> Arrays.fill( items, <strong>null</strong> );
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| <a name="71" href="#71">71</a> first = 0;
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| <a name="72" href="#72">72</a> last = 0;
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| <a name="73" href="#73">73</a> size = 0;
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| <a name="74" href="#74">74</a> }
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| <a name="75" href="#75">75</a>
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| <a name="76" href="#76">76</a> <em>/**<em>*</em></em>
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| <a name="77" href="#77">77</a> <em> * Dequeues from this queue.</em>
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| <a name="78" href="#78">78</a> <em> * </em>
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| <a name="79" href="#79">79</a> <em> * @return <code>null</code>, if this queue is empty or the element is</em>
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| <a name="80" href="#80">80</a> <em> * really <code>null</code>.</em>
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| <a name="81" href="#81">81</a> <em> */</em>
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| <a name="82" href="#82">82</a> <strong>public</strong> Object pop()
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| <a name="83" href="#83">83</a> {
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| <a name="84" href="#84">84</a> <strong>if</strong>( size == 0 )
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| <a name="85" href="#85">85</a> {
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| <a name="86" href="#86">86</a> <strong>return</strong> <strong>null</strong>;
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| <a name="87" href="#87">87</a> }
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| <a name="88" href="#88">88</a>
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| <a name="89" href="#89">89</a> Object ret = items[ first ];
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| <a name="90" href="#90">90</a> items[ first ] = <strong>null</strong>;
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| <a name="91" href="#91">91</a> first = ( first + 1 ) & mask;
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| <a name="92" href="#92">92</a>
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| <a name="93" href="#93">93</a> size--;
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| <a name="94" href="#94">94</a>
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| <a name="95" href="#95">95</a> <strong>return</strong> ret;
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| <a name="96" href="#96">96</a> }
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| <a name="97" href="#97">97</a>
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| <a name="98" href="#98">98</a> <em>/**<em>*</em></em>
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| <a name="99" href="#99">99</a> <em> * Enqueue into this queue.</em>
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| <a name="100" href="#100">100</a> <em> */</em>
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| <a name="101" href="#101">101</a> <strong>public</strong> <strong>void</strong> push( Object obj )
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| <a name="102" href="#102">102</a> {
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| <a name="103" href="#103">103</a> <strong>if</strong>( size == items.length )
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| <a name="104" href="#104">104</a> {
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| <a name="105" href="#105">105</a> <em class="comment">// expand queue</em>
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| <a name="106" href="#106">106</a> <strong>final</strong> <strong>int</strong> oldLen = items.length;
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| <a name="107" href="#107">107</a> Object[] tmp = <strong>new</strong> Object[ oldLen * 2 ];
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| <a name="108" href="#108">108</a>
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| <a name="109" href="#109">109</a> <strong>if</strong>( first < last )
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| <a name="110" href="#110">110</a> {
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| <a name="111" href="#111">111</a> System.arraycopy( items, first, tmp, 0, last - first );
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| <a name="112" href="#112">112</a> }
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| <a name="113" href="#113">113</a> <strong>else</strong>
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| <a name="114" href="#114">114</a> {
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| <a name="115" href="#115">115</a> System.arraycopy( items, first, tmp, 0, oldLen - first );
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| <a name="116" href="#116">116</a> System.arraycopy( items, 0, tmp, oldLen - first, last );
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| <a name="117" href="#117">117</a> }
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| <a name="118" href="#118">118</a>
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| <a name="119" href="#119">119</a> first = 0;
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| <a name="120" href="#120">120</a> last = oldLen;
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| <a name="121" href="#121">121</a> items = tmp;
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| <a name="122" href="#122">122</a> mask = tmp.length - 1;
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| <a name="123" href="#123">123</a> }
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| <a name="124" href="#124">124</a>
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| <a name="125" href="#125">125</a> items[ last ] = obj;
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| <a name="126" href="#126">126</a> last = ( last + 1 ) & mask;
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| <a name="127" href="#127">127</a> size++;
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| <a name="128" href="#128">128</a> }
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| <a name="129" href="#129">129</a>
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| <a name="130" href="#130">130</a> <em>/**<em>*</em></em>
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| <a name="131" href="#131">131</a> <em> * Returns the first element of the queue.</em>
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| <a name="132" href="#132">132</a> <em> * </em>
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| <a name="133" href="#133">133</a> <em> * @return <code>null</code>, if the queue is empty, or the element is</em>
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| <a name="134" href="#134">134</a> <em> * really <code>null</code>.</em>
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| <a name="135" href="#135">135</a> <em> */</em>
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| <a name="136" href="#136">136</a> <strong>public</strong> Object first()
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| <a name="137" href="#137">137</a> {
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| <a name="138" href="#138">138</a> <strong>if</strong>( size == 0 )
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| <a name="139" href="#139">139</a> {
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| <a name="140" href="#140">140</a> <strong>return</strong> <strong>null</strong>;
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| <a name="141" href="#141">141</a> }
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| <a name="142" href="#142">142</a>
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| <a name="143" href="#143">143</a> <strong>return</strong> items[ first ];
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| <a name="144" href="#144">144</a> }
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| <a name="145" href="#145">145</a>
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| <a name="146" href="#146">146</a> <strong>public</strong> Object last()
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| <a name="147" href="#147">147</a> {
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| <a name="148" href="#148">148</a> <strong>if</strong>( size == 0 )
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| <a name="149" href="#149">149</a> {
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| <a name="150" href="#150">150</a> <strong>return</strong> <strong>null</strong>;
|
| <a name="151" href="#151">151</a> }
|
| <a name="152" href="#152">152</a>
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| <a name="153" href="#153">153</a> <strong>return</strong> items[ ( last + items.length - 1 ) & mask ];
|
| <a name="154" href="#154">154</a> }
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| <a name="155" href="#155">155</a>
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| <a name="156" href="#156">156</a> <strong>public</strong> Object get( <strong>int</strong> idx )
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| <a name="157" href="#157">157</a> {
|
| <a name="158" href="#158">158</a> <strong>return</strong> items[ ( first + idx ) & mask ];
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| <a name="159" href="#159">159</a> }
|
| <a name="160" href="#160">160</a>
|
| <a name="161" href="#161">161</a> <em>/**<em>*</em></em>
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| <a name="162" href="#162">162</a> <em> * Returns <code>true</code> if the queue is empty.</em>
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| <a name="163" href="#163">163</a> <em> */</em>
|
| <a name="164" href="#164">164</a> <strong>public</strong> <strong>boolean</strong> isEmpty()
|
| <a name="165" href="#165">165</a> {
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| <a name="166" href="#166">166</a> <strong>return</strong> ( size == 0 );
|
| <a name="167" href="#167">167</a> }
|
| <a name="168" href="#168">168</a>
|
| <a name="169" href="#169">169</a> <em>/**<em>*</em></em>
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| <a name="170" href="#170">170</a> <em> * Returns the number of elements in the queue.</em>
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| <a name="171" href="#171">171</a> <em> */</em>
|
| <a name="172" href="#172">172</a> <strong>public</strong> <strong>int</strong> size()
|
| <a name="173" href="#173">173</a> {
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| <a name="174" href="#174">174</a> <strong>return</strong> size;
|
| <a name="175" href="#175">175</a> }
|
| <a name="176" href="#176">176</a>
|
| <a name="177" href="#177">177</a> <strong>public</strong> String toString()
|
| <a name="178" href="#178">178</a> {
|
| <a name="179" href="#179">179</a> <strong>return</strong> <span class="string">"first="</span> + first + <span class="string">", last="</span> + last + <span class="string">", size="</span> + size + <span class="string">", mask = "</span> + mask;
|
| <a name="180" href="#180">180</a> }
|
| <a name="181" href="#181">181</a> }
|
| </pre> |
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