如何在给定数组中执行二元搜索？

public class BinarySearch {	public int binarySearch(int a,int[] arr){        int index = -1;		int head = 0;		int end = arr.length - 1;		int binary =(end + head)/2;                // 使用二分查找进行搜索        while(true){			if( a <arr[head] || a > arr[end]){				break;		}		// 判断是否已经查找到					if(arr[binary] == a){			index = binary;			break;        }        else{			if(arr[binary] > a){				end = binary - 1;            		}            		else{				head = binary + 1;			}				binary =( end + head)/2;		}	}	return index;	}}