集合数组使用的区别

System.Collections 命名空间的一个类System.Collections.ArrayList实现了IList、Icollection、IEnumerable接口，但实现的方式比System.Array复杂。

数组的大小是固定的（不能增加或者删除元素）

ArrayLIst可以用于表示大小可变的项目列表；

下面用代码演示此结果

///  
    /// 抽象类
    ///  
     public abstract class Animal
    {
        private 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);
        }
    }

 ///  
    /// 派生类
    /// 
     public class Cow : Animal
    {
        public void Milk()
        {
            Console.WriteLine("{0} has been milked",Name);
        }
        public Cow(string newName)
            : base(newName)
        {
        }
    }
    /// 
    /// 派生类
    /// 
     public class Chicken : Animal
    {
        public void LayEgg()
        {
            Console.WriteLine("{0} has laid an egg", Name);
        }
        public Chicken(string newName)
            : base(newName)
        {
        }
    }

 

 实现方式：

 static void Main(string[] args)
        {
            Console.WriteLine("Create an Array type collection of Animal objects and use it:");
            Animal[] animalArray = new Animal[2];
            animalArray[0] = new Cow("Deirdre");
            animalArray[1] = new Chicken("Ken");
            foreach (Animal myAni in animalArray)
            {
                Console.WriteLine("New {0} object added to Array collection, Name= {1}", myAni.ToString(), myAni.Name);
            }
            animalArray[0].Feed();
            ((Cow)animalArray[0]).Milk();
            animalArray[1].Feed();
            ((Chicken)animalArray[1]).LayEgg();

            Console.WriteLine("Create an ArrayList type collection of Animal objects and use it:");
            ArrayList list = new ArrayList();
            list.Add(new Cow("HayLey"));
            list.Add(new Chicken("Roy"));
            foreach (Animal item in list)
            {
                Console.WriteLine("New {0} object added to ArrayList collection ,Name = {1} ", item.ToString(), item.Name);
            }
            Console.WriteLine("ArrayList collection contains {0} objects.", list.Count);
            ((Animal)list[0]).Feed();
            ((Cow)list[0]).Milk();
            ((Animal)list[1]).Feed();
            ((Chicken)list[1]).LayEgg();

            list.RemoveAt(0);
            ((Animal)list[0]).Feed();
            ((Chicken)list[0]).LayEgg();
            list.AddRange(animalArray);
            Cow c = new Cow("small cow");
            list.Add(c);
            c.Name = "Big cow";
            ((Cow)list[3]).Milk();
        }