对集合排序，可能最先想到的是使用OrderBy方法。
class Program
{
static void Main(string[] args)
{
IEnumerable<Student> result = GetStudents().OrderBy(r => r.Score);
foreach (var item in result)
{
Console.WriteLine(item.Name + "--" + item.Score);
}
Console.ReadKey();
}
private static List<Student> GetStudents()
{
return new List<Student>()
{
new Student(){Id = 1, Name = "张三",Age = 15, Score = 80},
new Student(){Id = 2, Name = "李四",Age = 16, Score = 70},
new Student(){Id = 3, Name = "赵武",Age = 14, Score = 90}
};
}
}
public class Student
{
public int Id { get; set; }
public string Name { get; set; }
public int Age { get; set; }
public int Score { get; set; }
}
以上，OrderBy返回的类型是IEnumerable<Student>。
如果想使用List<T>的Sort方法，就需要让Student实现IComparable<Student>接口。
class Program
{
static void Main(string[] args)
{
List<Student> result = GetStudents();
result.Sort();
foreach (var item in result)
{
Console.WriteLine(item.Name + "--" + item.Score);
}
Console.ReadKey();
}
private static List<Student> GetStudents()
{
return new List<Student>()
{
new Student(){Id = 1, Name = "张三",Age = 15, Score = 80},
new Student(){Id = 2, Name = "李四",Age = 16, Score = 70},
new Student(){Id = 3, Name = "赵武",Age = 14, Score = 90}
};
}
}
public class Student : IComparable<Student>
{
public int Id { get; set; }
public string Name { get; set; }
public int Age { get; set; }
public int Score { get; set; }
public int CompareTo(Student other)
{
return this.Score.CompareTo(other.Score);
}
}
让Student实现IComparable<Student>接口固然很好，如果Student是一个密封类，我们无法让其实现IComparable<Student>接口呢？不用担心，Sort方法提供了一个重载，可以接收IComparer接口类型。
class Program
{
static void Main(string[] args)
{
List<Student> result = GetStudents();
result.Sort(new StudentSorter());
foreach (var item in result)
{
Console.WriteLine(item.Name + "--" + item.Score);
}
Console.ReadKey();
}
private static List<Student> GetStudents()
{
return new List<Student>()
{
new Student(){Id = 1, Name = "张三",Age = 15, Score = 80},
new Student(){Id = 2, Name = "李四",Age = 16, Score = 70},
new Student(){Id = 3, Name = "赵武",Age = 14, Score = 90}
};
}
}
public class Student
{
public int Id { get; set; }
public string Name { get; set; }
public int Age { get; set; }
public int Score { get; set; }
}
public class StudentSorter : IComparer<Student>
{
public int Compare(Student x, Student y)
{
return x.Score.CompareTo(y.Score);
}
}
综上，如果我们想对一个集合排序，大致有三种方式：
1、使用OrderBy方法，返回IEnumerable<T>类型。
2、让集合元素实现IComparable<T>接口，再使用Sort方法，返回void。
3、集合元素不实现IComparable<T>接口，针对集合元素类型写一个实现IComparer<T>接口的类，把该类实例作为Sort方法的参数。