public int find(long searchKey){                int i;        int begin = 0;        int end = nElems - 1;                        while(true){            i = (begin + end) / 2;                        if (searchKey == a[i]){                return i;            } else if (begin > end) {                return -1;            } else if (searchKey > a[i]) {                begin = i + 1;            } else if (searchKey < a[i]) {                end = i - 1;             }        }    }

其中a是待查有序数组，searchKey是待查数值。

查询次数为num = log2(a.length)即数组长度的对数