折半查找_Java

public class Search002 {
public static void main(String [] args){
int [] a={1,2,3,4,5,6,7,8,9};
int num=8;
int res=search(a,7);
System.out.println(res);
}
public static int search(int [] a,int num){
int low=0;
int high=a.length-1;
while(low<=high){
int mid=(low+high)/2;
if(a[mid]<num)
low=mid+1;
else if(a[mid]>num)
high=mid-1;
else
return mid;
}
return -1;
}
}