Java实现折半查找（二分法）

package test;
/*
 * 二分法查找（折半查找）
 * TGmoving
 * */
public class halfSearch {

    public static int HalfSearch(int a[],int data){
        
        int length = a.length;
        int start = 0;
        int end = length - 1;
        int middle = (start + end) / 2;
        int count = 1; //用于计数，折半查找次数超过20次仍未找到视为不存在该元素
        
        while(data!=a[middle]){ 
            if(start > end || count > 20){
                return -1;
            }else{
                if(data < a[middle]){
                    end = middle;
                    middle = (start + end) / 2;
                    System.out.println("第"+(count+1)+"次查找 data < a[middle]: "+ "索引为："+middle);
                }else if(data > a[middle]){
                    start = middle + 1;
                    middle = (start + end ) / 2;
                    System.out.println("第"+(count+1)+"次查找 data > a[middle]: "+ "索引为："+middle);
                }
            }
            count++;
        }
        count = 0;
        return middle;
    }
    
    
    public static void main(String[]Args){
        
        int a[] = {1,2,3,4,5,6,7};
        int index = HalfSearch(a, 7);
        System.out.println("isExist:"+ index );
        
    }
}