二分查找java代码

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