c# - Dictionary> 到 IDictionary>？

Question

请考虑以下代码:

class Student
{
}

enum StudentType
{
}

static void foo(IDictionary<StudentType, IList<Student>> students)
{   
}

static void Main(string[] args)
{
    Dictionary<StudentType, List<Student>> studentDict = 
                     new Dictionary<StudentType, List<Student>>();

    foo(studentDict);

    ...
}

出现错误:

error CS1503: Argument '1': cannot convert from 'System.Collections.Generic.Dictionary>' to 'System.Collections.Generic.IDictionary>'

有什么方法可以调用foo函数吗？

Answer 1

您可以使用 Linq ToDictionary 方法创建一个新字典，其中的值具有正确的类型:

static void Main(string[] args)
{
  Dictionary<StudentType, List<Student>> studentDict = new Dictionary<StudentType, List<Student>>();
  var dicTwo = studentDict.ToDictionary(item => item.Key, item => (IList<Student>)item.Value);
  foo(dicTwo);
}