Provide different IComparer for a Class : Generic IComparer : Generic C# Examples

    
using  System;
using  System.Collections.Generic;

public  class  Employee  :  IComparable<Employee>
{
        private  string  name;
        private  int  level;

        private  class  AscendingLevelComparer  :  IComparer<Employee>
        {
                public  int  Compare(Employee  x,  Employee  y)
                {
                        if  (x  ==  null  &&  y  ==  null)  
                              return  0;
                        else  if  (x  ==  null)  
                              return  -1;
                        else  if  (y  ==  null)  
                              return  1;

                        if  (x  ==  y)  
                              return  0;

                        return  x.level  -  y.level;
                }
        }

        public  Employee(string  name,  int  level)
        {
                this.name  =  name;
                this.level  =  level;
        }

        public  static  IComparer<Employee>  LevelSorter
        {
                get  {  return  new  AscendingLevelComparer();  }
        }

        public  override  string  ToString()
        {
                return  string.Format("{0}:  Level  =  {1}",  name,  level);
        }

        public  int  CompareTo(Employee  other)
        {
                if  (other  ==  null)  
                        return  1;

                if  (other  ==  this)  
                        return  0;
                return  string.Compare(this.name,  other.name,  true);
        }
}

public  class  MainClass
{
        public  static  void  Main()
        {
                List<Employee>  employeeList  =  new  List<Employee>();

                employeeList.Add(new  Employee("A",  1));
                employeeList.Add(new  Employee("B",  5));
                employeeList.Add(new  Employee("C",  2));
                employeeList.Add(new  Employee("D",  8));
                employeeList.Add(new  Employee("E",  5));

                
                Console.WriteLine("Unsorted  employee  list:");
                foreach  (Employee  n  in  employeeList)
                {
                        Console.WriteLine("    "  +  n);
                }

                Console.WriteLine(Environment.NewLine);  
                Console.WriteLine("Employee  list  sorted  by  name  (default  order):");
                employeeList.Sort();
                foreach  (Employee  n  in  employeeList)
                {
                        Console.WriteLine("    "  +  n);
                }

                Console.WriteLine(Environment.NewLine);  
                Console.WriteLine("Employee  list  sorted  by  level:");
                employeeList.Sort(Employee.LevelSorter);
                foreach  (Employee  n  in  employeeList)
                {
                        Console.WriteLine("    "  +  n);
                }
      }
}