Java二分法查找

public class demo3 {
    public static void main(String[] args) {
        int[] a=new int[]{1,2,3,4,5,6,7,8,9};
    //二分法查找,所查找的数组必须有序
        boolean b=true;
        int target=4;
        int head=0;//定义初始化位置
        int end=a.length-1;//定义末端位置
        while(head<=end){
            int middle=(head+end)/2;
            if (target==a[middle]){
             	b=false;
         		System.out.println("找到了,目标位置为："+middle);
                break;
                }else if(a[middle]>target){
                end=middle-1;
            }
            else {
                head = middle + 1;
            }
        }
        if(b) {
            System.out.println("很遗憾，没找到目标位置");
        }
    }
}