创建三个自定义类和集合。

animal类。

using System;namespace a{	public abstract class Animal	{		protected string name;		public string Name		{			get			{				return name;			}			set			{				name=value;			}		}		public Animal()		{			name="The animal with no name";		}		public Animal (string newName)		{			name=newName;		}		public void Feed()		{			Console.WriteLine("{0} has been fed.",name);		}	}}

chicken类。

using System;namespace a{	public class Chicken:Animal	{		public void LayEgg()		{			Console.WriteLine("{0} has laid an egg.",name);		}		public Chicken(string newName):base(newName)		{		}	}}

cow类。

using System;namespace a{	public class Cow:Animal	{		public void Milk()		{			Console.WriteLine("{0} has been milked.",name);		}		public Cow(string newName):base(newName)		{		}	}}

programe.cs.

using System;using System.Collections;using System.Collections.Generic;using System.Text;namespace a{	class Program	{		static void Main(string[] args)		{			Console.WriteLine("Create an Array type collection of Animal"+"objects and use it:");			Animal[] animalArray=new Animal[2];			Cow myCow1=new Cow("Deirdre");			animalArray[0]=myCow1;			animalArray[1]=new Chicken("ken");			foreach(Animal myAnimal in animalArray)			{				Console.WriteLine("New {0} object added to Array collection,"+"Name={1}",myAnimal.ToString(),myAnimal.Name);			}			Console.WriteLine("Array collection contains {0} objects.",animalArray.Length);			animalArray[0].Feed();			((Chicken)animalArray[1]).LayEgg();			Console.WriteLine();			Console.WriteLine("Create an ArrayList type collection of Animal"+"objects and use it:");			ArrayList animalArrayList=new ArrayList();			Cow myCow2=new Cow("Hayleg");			animalArrayList.Add(myCow2);			animalArrayList.Add(new Chicken("Roy"));			foreach (Animal myAnimal in animalArrayList)			{				Console.WriteLine("New {0} object added to ArrayList collection,"+"Name={1}",myAnimal.ToString(),myAnimal.Name);			}			Console.WriteLine("ArrayList collection contains {0} objects.",animalArrayList.Count);			((Animal)animalArrayList[0]).Feed();			((Chicken)animalArrayList[1]).LayEgg();			Console.WriteLine();			Console.WriteLine("Additional manipulation of ArrayList:");			animalArrayList.RemoveAt(0);			((Animal)animalArrayList[0]).Feed();			animalArrayList.AddRange(animalArray);			((Chicken)animalArrayList[2]).LayEgg();			Console.WriteLine("The animal called {0} is at index {1}.",myCow1.Name,animalArrayList.IndexOf(myCow1));			myCow1.Name="Janice";			Console.WriteLine("The animal is now called {0}.",((Animal)animalArrayList[1]).Name);			Console.ReadKey();		}	}}