Java实现二分查找

public class BinarySearch {
        /**
        * 二分查找算法
        *
        * @param srcArray 有序数组
        * @param key 查找元素
        * @return key的数组下标，没找到返回-1
        */
        public static void main(String[] args) {
            int srcArray[] = {3,5,11,17,21,23,28,30,32,50,64,78,81,95,101};
            System.out.println(binSearch(srcArray, 0, srcArray.length - 1, 81));
        } 

        // 二分查找递归实现
        public static int binSearch(int srcArray[], int start, int end, int key) {   

            int mid = (end - start) / 2 + start;
            if (srcArray[mid] == key) {
                return mid;
            }
            if (start >= end) {
                return -1;
            } else if (key > srcArray[mid]) {
                return binSearch(srcArray, mid + 1, end, key);
            } else if (key < srcArray[mid]) {
                return binSearch(srcArray, start, mid - 1, key);
            }
            return -1;
        } 

        // 二分查找普通循环实现
        public static int binSearch(int srcArray[], int key) {
            int mid = srcArray.length / 2;
            if (key == srcArray[mid]) {
                return mid;
            }   

            int start = 0;
            int end = srcArray.length - 1;
            while (start <= end) {
                mid = (end - start) / 2 + start;
                if (key < srcArray[mid]) {
                   end = mid - 1;
                } else if (key > srcArray[mid]) {
                    start = mid + 1;
                } else {
                    return mid;
                }
            }
            return -1;
        }
    }