Dart 二进制搜索 function 不工作

Question

This is my function and it always returns -1. It prints right value of mid, but never returns it.

int binarySearch(List<int> arr, int userValue, int min, int max) {
    if (min >= 0) {
      int mid = ((max + min) / 2).floor();
      if (userValue == arr[mid]) {
        print(mid);
        return mid;
      } else if (userValue > arr[mid]) {
        binarySearch(arr, userValue, mid + 1, max);
      } else {
        binarySearch(arr, userValue, min, mid - 1);
      }
    }
    return -1;
  }

Usage of function

int result = binarySearch(dates, 22, 0, 30);

Answer 1

Binarysearch function

void Binarysearch(

    List list,
    int value,
    int min,
    int max

) 

Implementation

void Binarysearch(List list, int value, int min, int max)
{
  if(min > max) // Checking the list size with min and max
  {
    return null;
  }

  int mid = (max + min) ~/ 2;  // taking the mid value using min and max values of the list

  if(value < list[mid])  // Checking the given value is lessthen the mid value
  {
     return Binarysearch(list, value, min, mid - 1);  // ittarating the search method untill value is find
  }
  else if(value > list[mid])  // Checking the given value is greaterthen the mid value
  {
    return Binarysearch(list, value, mid + 1, max);  //ittarating the search method untill value is find
  }
  else
  {
    print("The $value is find at possition :$mid");  // finaly return the value
  }
}