请帮忙看下代码有什么东东

//二分查找class  SecondFind{    public static void main(String[] args)     {        //定义数组        int [] data=new int[]{2,3,4,5,6,7,8,9};        int index=getIndex(data,77);        System.out.print("index="+index);    }    public static int getIndex(int []arr,int num){        int min=0,max=arr.length-1;        int mid=(min+max)/2;        while(arr[max]>=arr[min]){            mid=(min+max)/2;            if(num>arr[mid])                min=mid+1;            else if (num<arr[mid])                max=mid-1;            else                 return mid;            }            return -1;                 }        }