IComparable<Student>是Student的父类,所以IComparable<Student>可以接收Student。
但是在使用CompareTo方法的时候,必须传入Student,不允许传入父类IComparable<Student>。
public interface IComparable<in T>
public class Student : IComparable<Student> { public int Id { get; set; } public int CompareTo(Student other) { return Id - other.Id; } } class Test { public Test() { IComparable<Student> student1 = new Student() {Id = 1}; IComparable<Student> student2 = new Student() {Id = 2}; int result = student1.CompareTo(student2); } }