[code]二分法:從已排好序的String數組中查詢要搜尋的字串的下標

package utils.find;<br />import java.lang.reflect.Array;<br />/**<br /> * ArrayUtil <br/><br /> * Generated on: 2010.05.07<br /> *<br /> * @author loocao<br /> */<br />public class ArrayUtil {<br />/**<br /> * @param args<br /> */<br />public static void main(String[] args) {<br />String[] arrString = new String[] { "abc0", "cde1", "efg2", "hij3",<br />"lmn4", "opq5", "rst6", "uvw7", "xyz8" };<br />String findStr = "rst6";<br />System.out.println(indexOfStringArray(arrString, findStr));<br />}<br />/**<br /> * 從已排好序的String數組中查詢要搜尋的字串的下標<br /> *<br /> * @param args<br /> * 已經排序的字串數組<br /> * @param findStr<br /> * 要尋找的字串<br /> * @return 字串所在<b>下標<b><br /> */<br />public static int indexOfStringArray(String[] args, String findStr) {<br />if (findStr == null || args == null || args.length == 0)<br />return -1;<br />int index = args.length % 2 == 0 ? args.length / 2<br />: (args.length - 1) / 2;<br />if (args[index].equals(findStr)) {<br />return index;<br />} else {<br />int temp, result = 0, start = 0, length = 0;<br />if (findStr.compareTo(args[index]) < 0) {<br />start = 0;<br />length = index;// index之前的數組長度<br />temp = indexOfStringArray(subArray(args, start, length),<br />findStr);<br />result = temp;<br />} else if (findStr.compareTo(args[index]) > 0) {<br />start = index + 1;<br />length = args.length - start;// index之後的數組length<br />temp = indexOfStringArray(subArray(args, start, length),<br />findStr);<br />if (temp == -1)<br />result = temp;<br />else<br />result = temp + index + 1;<br />}<br />return result;<br />}<br />}<br />/**<br /> * 截取數組<br /> *<br /> * 感謝enihs( http://hi.csdn.net/shine333 )指點,<br /> * System.arraycopy: http://doc.java.sun.com/DocWeb/api/java.lang.System?lang=zh_cn&mode=Read#T3<br /> *<br /> * @param c<br /> * args數組中元素的類型class<br /> * @param args<br /> * 要截取的數組<br /> * @param start<br /> * 開始下標<br /> * @param length<br /> * 要複製的數組長度<br /> * @return args 中下標從 start 到 start+length-1 的數組<br /> */<br />@SuppressWarnings("unchecked")<br />public static <T> T[] subArray(T[] args, int start, int length) {<br />T[] temp = (T[]) Array.newInstance(args.getClass().getComponentType(),<br />length);<br />// for (int i = start; i <= start + length - 1; i++) {<br />// temp[i - start] = args[i];<br />// }</p><p>// 將數組args從start到length-1複製到temp中,由enihs指點<br />System.arraycopy(args, start, temp, 0, length);<br />return temp;<br />}<br />}