帮写一个二分查找算法java

public class BinarySearch {
public static int binarySearch(int[] arr, int target) {
int left = 0;
int right = arr.length - 1;
while (left <= right) {
int mid = (left + right) / 2;
if (arr[mid] == target)
return mid;
else if (arr[mid] < target)
left = mid + 1;
else
right = mid - 1;
}
return -1;
}
}

// 测试
public class Main {
public static void main(String[] args) {
int[] arr = {1, 2, 3, 4, 5, 6, 7, 8, 9};
int target = 6;
int index = BinarySearch.binarySearch(arr, target);
if (index == -1)
System.out.println("未找到");
else
System.out.println("目标元素下标为：" + index);
}
}