java 二分查找

package day04;

public class ArrTest2 {
    /*
    数组的二分法查找： 查找注意事项：
    1.对于一个有序的数组从中间查找，如果目标值比中间的索引值大，则说明值在右边，否则值在左边，继续往下查找
     */
    public static void main(String[] args) {


        int [] arr = new int[] {-34,-31,1,5,8,34,67,78,98,145,234,321};

        int target =146;
        int index = -1;
        int end = arr.length-1;
        int begin = 0;
        boolean isFlage =true;  //找到标志位
        while (begin <=end){
            int mid = (end+begin)/2;
            if(target==arr[mid]){
                System.out.println("找到了");
                isFlage =false;
                break;
            }else if(arr[mid] > target){
                end = mid-1;
            }else {
                begin =mid+1;
            }

        }
        if(isFlage){
            System.out.println("没有找到哦");
        }


    }
}