随机数发生器代码,Java代码库,德仔网

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【Java】随机数发生器
作者: / 发布于2011/1/14/ 534
<div><span style="color: #0000ff">import</span><span style="color: #000000"> java.util.Arrays;
</span><span style="color: #0000ff">import</span><span style="color: #000000"> java.util.Random;
</span><span style="color: #008000">/**</span><span style="color: #008000">
* RandomUtil - Random Tool Class.
* </span><span style="color: #808080">@author</span><span style="color: #008000"> SageZk
* </span><span style="color: #808080">@version</span><span style="color: #008000"> 1.0
</span><span style="color: #008000">*/</span><span style="color: #000000">
</span><span style="color: #0000ff">public</span><span style="color: #000000"> </span><span style="color: #0000ff">class</span><span style="color: #000000"> RandomUtil {

 </span><span style="color: #0000ff">private</span><span style="color: #000000"> RandomUtil() {}

 </span><span style="color: #0000ff">private</span><span style="color: #000000"> </span><span style="color: #0000ff">static</span><span style="color: #000000"> Random rnd </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #0000ff">null</span><span style="color: #000000">;

 </span><span style="color: #008000">/**</span><span style="color: #008000">
 * 初始化随机数发生器。
 </span><span style="color: #008000">*/</span><span style="color: #000000">
 </span><span style="color: #0000ff">private</span><span style="color: #000000"> </span><span style="color: #0000ff">static</span><span style="color: #000000"> </span><span style="color: #0000ff">void</span><span style="color: #000000"> initRnd() {
 </span><span style="color: #0000ff">if</span><span style="color: #000000"> (rnd </span><span style="color: #000000">==</span><span style="color: #000000"> </span><span style="color: #0000ff">null</span><span style="color: #000000">) rnd </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #0000ff">new</span><span style="color: #000000"> Random();
 }

 </span><span style="color: #008000">/**</span><span style="color: #008000">
 * 计算并返回无重复值的以 min 为下限 max 为上限的随机整数数组。
 * </span><span style="color: #808080">@param</span><span style="color: #008000"> min 随机整数下限（包含）
 * </span><span style="color: #808080">@param</span><span style="color: #008000"> max 随机整数上限（包含）
 * </span><span style="color: #808080">@param</span><span style="color: #008000"> len 结果数组长度
 * </span><span style="color: #808080">@return</span><span style="color: #008000"> 结果数组
 </span><span style="color: #008000">*/</span><span style="color: #000000">
 </span><span style="color: #0000ff">public</span><span style="color: #000000"> </span><span style="color: #0000ff">static</span><span style="color: #000000"> </span><span style="color: #0000ff">int</span><span style="color: #000000">[] getLotteryArray(</span><span style="color: #0000ff">int</span><span style="color: #000000"> min, </span><span style="color: #0000ff">int</span><span style="color: #000000"> max, </span><span style="color: #0000ff">int</span><span style="color: #000000"> len) {
 </span><span style="color: #008000">//</span><span style="color: #008000">参数校验及性能优化</span><span style="color: #008000">
</span><span style="color: #000000"> </span><span style="color: #0000ff">if</span><span style="color: #000000"> (len </span><span style="color: #000000"><</span><span style="color: #000000"> </span><span style="color: #000000">0</span><span style="color: #000000">) </span><span style="color: #0000ff">return</span><span style="color: #000000"> </span><span style="color: #0000ff">null</span><span style="color: #000000">; </span><span style="color: #008000">//</span><span style="color: #008000">长度小于 0 的数组不存在</span><span style="color: #008000">
</span><span style="color: #000000"> </span><span style="color: #0000ff">if</span><span style="color: #000000"> (len </span><span style="color: #000000">==</span><span style="color: #000000"> </span><span style="color: #000000">0</span><span style="color: #000000">) </span><span style="color: #0000ff">return</span><span style="color: #000000"> </span><span style="color: #0000ff">new</span><span style="color: #000000"> </span><span style="color: #0000ff">int</span><span style="color: #000000">[</span><span style="color: #000000">0</span><span style="color: #000000">]; </span><span style="color: #008000">//</span><span style="color: #008000">返回长度为 0 的数组</span><span style="color: #008000">
</span><span style="color: #000000"> </span><span style="color: #0000ff">if</span><span style="color: #000000"> (min </span><span style="color: #000000">></span><span style="color: #000000"> max) { </span><span style="color: #008000">//</span><span style="color: #008000">校正参数 min max</span><span style="color: #008000">
</span><span style="color: #000000"> </span><span style="color: #0000ff">int</span><span style="color: #000000"> t </span><span style="color: #000000">=</span><span style="color: #000000"> min;
 min </span><span style="color: #000000">=</span><span style="color: #000000"> max;
 max </span><span style="color: #000000">=</span><span style="color: #000000"> t;
 }
 </span><span style="color: #0000ff">final</span><span style="color: #000000"> </span><span style="color: #0000ff">int</span><span style="color: #000000"> LEN </span><span style="color: #000000">=</span><span style="color: #000000"> max </span><span style="color: #000000">-</span><span style="color: #000000"> min </span><span style="color: #000000">+</span><span style="color: #000000"> </span><span style="color: #000000">1</span><span style="color: #000000">; </span><span style="color: #008000">//</span><span style="color: #008000">种子个数</span><span style="color: #008000">
</span><span style="color: #000000"> </span><span style="color: #0000ff">if</span><span style="color: #000000"> (len </span><span style="color: #000000">></span><span style="color: #000000"> LEN) </span><span style="color: #0000ff">return</span><span style="color: #000000"> </span><span style="color: #0000ff">null</span><span style="color: #000000">; </span><span style="color: #008000">//</span><span style="color: #008000">如果出现 35 选 36 的情况就返回 null
 </span><span style="color: #008000">//</span><span style="color: #008000">计算无重复值随机数组</span><span style="color: #008000">
</span><span style="color: #000000"> initRnd(); </span><span style="color: #008000">//</span><span style="color: #008000">初始化随机数发生器</span><span style="color: #008000">
</span><span style="color: #000000"> </span><span style="color: #0000ff">int</span><span style="color: #000000">[] seed </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #0000ff">new</span><span style="color: #000000"> </span><span style="color: #0000ff">int</span><span style="color: #000000">[LEN]; </span><span style="color: #008000">//</span><span style="color: #008000">种子数组</span><span style="color: #008000">
</span><span style="color: #000000"> </span><span style="color: #0000ff">for</span><span style="color: #000000"> (</span><span style="color: #0000ff">int</span><span style="color: #000000"> i </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #000000">0</span><span style="color: #000000">, n </span><span style="color: #000000">=</span><span style="color: #000000"> min; i </span><span style="color: #000000"><</span><span style="color: #000000"> LEN;) seed[i</span><span style="color: #000000">++</span><span style="color: #000000">] </span><span style="color: #000000">=</span><span style="color: #000000"> n</span><span style="color: #000000">++</span><span style="color: #000000">; </span><span style="color: #008000">//</span><span style="color: #008000">初始化种子数组</span><span style="color: #008000">
</span><span style="color: #000000"> </span><span style="color: #0000ff">for</span><span style="color: #000000"> (</span><span style="color: #0000ff">int</span><span style="color: #000000"> i </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #000000">0</span><span style="color: #000000">, j </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #000000">0</span><span style="color: #000000">, t </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #000000">0</span><span style="color: #000000">; i </span><span style="color: #000000"><</span><span style="color: #000000"> len; </span><span style="color: #000000">++</span><span style="color: #000000">i) {
 j </span><span style="color: #000000">=</span><span style="color: #000000"> rnd.nextInt(LEN </span><span style="color: #000000">-</span><span style="color: #000000"> i) </span><span style="color: #000000">+</span><span style="color: #000000"> i;
 t </span><span style="color: #000000">=</span><span style="color: #000000"> seed[i];
 seed[i] </span><span style="color: #000000">=</span><span style="color: #000000"> seed[j];
 seed[j] </span><span style="color: #000000">=</span><span style="color: #000000"> t;
 }
 </span><span style="color: #0000ff">return</span><span style="color: #000000"> Arrays.copyOf(seed, len); </span><span style="color: #008000">//</span><span style="color: #008000">注意：copyOf 需要 JRE1.6</span><span style="color: #008000">
</span><span style="color: #000000"> }

 </span><span style="color: #008000">//</span><span style="color: #008000">Unit Testing</span><span style="color: #008000">
</span><span style="color: #000000"> </span><span style="color: #0000ff">public</span><span style="color: #000000"> </span><span style="color: #0000ff">static</span><span style="color: #000000"> </span><span style="color: #0000ff">void</span><span style="color: #000000"> main(String[] args) {
 </span><span style="color: #0000ff">final</span><span style="color: #000000"> </span><span style="color: #0000ff">int</span><span style="color: #000000"> N </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #000000">10000</span><span style="color: #000000">; </span><span style="color: #008000">//</span><span style="color: #008000">测试次数</span><span style="color: #008000">
</span><span style="color: #000000"> </span><span style="color: #0000ff">for</span><span style="color: #000000"> (</span><span style="color: #0000ff">int</span><span style="color: #000000"> i </span><span style="color: #000000">=</span><span style="color: #000000"> </span><span style="color: #000000">0</span><span style="color: #000000">; i </span><span style="color: #000000"><</span><span style="color: #000000"> N; </span><span style="color: #000000">++</span><span style="color: #000000">i) {
 </span><span style="color: #0000ff">int</span><span style="color: #000000">[] la </span><span style="color: #000000">=</span><span style="color: #000000"> RandomUtil.getLotteryArray(</span><span style="color: #000000">1</span><span style="color: #000000">, </span><span style="color: #000000">35</span><span style="color: #000000">, </span><span style="color: #000000">7</span><span style="color: #000000">);
 </span><span style="color: #0000ff">if</span><span style="color: #000000"> (la </span><span style="color: #000000">==</span><span style="color: #000000"> </span><span style="color: #0000ff">null</span><span style="color: #000000">) </span><span style="color: #0000ff">continue</span><span style="color: #000000">;
 </span><span style="color: #0000ff">for</span><span style="color: #000000"> (</span><span style="color: #0000ff">int</span><span style="color: #000000"> v : la) System.out.printf(</span><span style="color: #000000">"</span><span style="color: #000000">%0$02d </span><span style="color: #000000">"</span><span style="color: #000000">, v);
 System.out.println();
 }
 }

}</span>
</div>
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