二分查找

java实现一个简单的二分查找

public static int bsearch(int[] a, int n, int value) {//a是查找目标数组,n是数组长度,value是查找的值
        int low = 0;
        int high = n - 1;

        while (low <= high) {
          int mid = (low + high) / 2;
          if (a[mid] == value) {
            return mid;
          } else if (a[mid] < value) {
            low = mid + 1;
          } else {
            high = mid - 1;
          }
        }

        return -1;
      }

    @Test
    public void test1(){
        int[] a={1,2,3,4,5,6,7,8,9};
        int value=9;
        System.out.println(bsearch(a,a.length,value));
    }