集合 ArrayList

1.使用集合：

添加三个类Animal.cs  Cow.cs  Chiken.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace collection
{
    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 feed.", name);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace collection
{
    class Cow : Animal
    {
        public void Milk()
        {
            Console.WriteLine("{0} has been milkd", name);
        }

        public Cow(string newName)
            : base(newName)
        {
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace collection
{
    public class Chiken:Animal
    {
        public void LayEgg()
        {
            Console.WriteLine("{0} has laid an egg.",name);
        }

        public Chiken(string newName):base(newName)
        { }
    }
}

输出端

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace collection
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("创造一个Array类型收集的动物 " +
                "对象并使用它:");
            Animal[] animalArray = new Animal[2];
            Cow myCow1 = new Cow("Deirdre");
            animalArray[0] = myCow1;
            animalArray[1] = new Chiken("Ken");

            foreach (Animal myAnimal in animalArray)
            {
                Console.WriteLine("New {0} object added to Array collection, " +
                    "Name = {1}", myAnimal.ToString(), myAnimal.Name);
            }
            //Array.Length
            Console.WriteLine("Array collection contains {0} objects.", animalArray.Length);
            //Array调用方法时，类型转换
            animalArray[0].Feed();
            ((Chiken)animalArray[1]).LayEgg();
            Console.WriteLine("===================");

            Console.WriteLine("创造一个ArrayList类型收集的动物" +
                "对象并使用它:");

            ArrayList animalArrayList = new ArrayList();
            Cow myCow2 = new Cow("Hayley");
            animalArrayList.Add(myCow2);
            animalArrayList.Add(new Chiken("Roy"));

            foreach (Animal myAnimal in animalArrayList)
            {
                Console.WriteLine("New {0} object added to ArrayList collection," +
                    "Name = {1}", myAnimal.ToString(), myAnimal.Name);
            }
            //ArrayList.Count
            Console.WriteLine("ArrayList collection contains {0} objects.", animalArrayList.Count);
            //ArrayList调用方法时，类型转换
            ((Animal)animalArrayList[0]).Feed();
            ((Chiken)animalArrayList[1]).LayEgg();
            Console.WriteLine("===================");

            Console.WriteLine("其他的处理ArrayList的:");
            //RemoveAt
            animalArrayList.RemoveAt(0);
            ((Animal)animalArrayList[0]).Feed();
            //AddRange
            animalArrayList.AddRange(animalArray);
            ((Chiken)animalArrayList[2]).LayEgg();
            Console.WriteLine("=========animalArrayList列表内容==========");
            foreach (Animal item in animalArrayList)
            {
                Console.Write(item+" : "+item.Name+" \n" );
            }
            Console.WriteLine("========IndexOf===========");
            //IndexOf
            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.Read();
        }
    }
}

 

2.定义集合：

CollectionBase类有接口IEnumerable、 IList 和 ICollection 。

存储Animal对象的集合如下

public class Animals:CollectionBase
    {
        public Animals()
        {

        }
        public void Add(Animal newAnimal)
        {
            List.Add(newAnimal);
        }
        public void Remove(Animal oldAnimal)
        {
            List.Remove(oldAnimal);
        }
}

CollectionBase类可以对派生的集合使用 foreach语句，

Animals animalCollection = new Animals();
            animalCollection.Add(new Cow("Tang"));
            animalCollection.Add(new Chiken("San"));
            foreach (Animal  item in animalCollection)
            {
                
                Console.WriteLine("{0},{1}", item.ToString(), item.Name);
            }

但是不能使用

animalCollection[0].Feed();
要以这种方式实现，必须使用索引符。

3.索引符

public Animal this[int animalIndex]
        {
            get
            {
                return (Animal)List[animalIndex];
            }
            set
            {
                List[animalIndex] = value;
            }
        }

所以，在原有的3个Animal.cs，Cow.cs，Chiken.cs上，添加一个Animals.cs

using System;
using System.Collections.Generic;
using System.Collections;
using System.Linq;
using System.Text;

namespace Ch11Ex2
{
    public class Animals:CollectionBase
    {
        public Animals()
        {

        }
        public void Add(Animal newAnimal)
        {
            List.Add(newAnimal);
        }
        public void Remove(Animal oldAnimal)
        {
            List.Remove(oldAnimal);
        }
        public Animal this[int animalIndex]
        {
            get
            {
                return (Animal)List[animalIndex];
            }
            set
            {
                List[animalIndex] = value;
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Ch11Ex2
{
    class Program
    {
        static void Main(string[] args)
        {
            Animals animalCollection = new Animals();
            animalCollection.Add(new Cow("AAAAAA"));
            animalCollection.Add(new Chiken("BBBBBB"));
            foreach (Animal  item in animalCollection)
            {
                //item.Feed();
                Console.WriteLine("{0},{1}", item.ToString(), item.Name);
            }
            //只有实现索引符(indexer)
            //public Animal this[int animalIndex]
            //才可以使用下面的方法
            animalCollection[0].Feed();
            Console.Read();
        }
    }
}