二分查找

这个代码是为了复习算法。

public static void main(String[] args) {int[] test = { 1, 2, 3, 4, 5, 6, 7, 8 };System.out.println(middle(test, 9));}public static int middle(int[] a, int key) {if (null == a || a.length < 1) {return -1;}int start = 0;int end = a.length - 1;int middle = 0;while (start <= end) {middle = (start + end) >> 1;if (key == a[middle]) {return middle;}if (key < a[middle]) {end = middle - 1;}if (key > a[middle]) {start = middle + 1;}}return -1;}