属性 索引的使用

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

namespace Model
{
    public class ArticleCollection : CollectionBase
    {
        private int articleCount;
        /// <summary>
        /// 文章数量
        /// </summary>
        public int ArticleCount
        {
            get { return articleCount; }
            set { articleCount = value; }
        }

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

        public void Add(ArticleModel article)
        {
            List.Add(article);
        }

        public ArticleModel GetArticleModelByArticleID(int articleID)
        {
            ArticleModel article = new ArticleModel();
            foreach (ArticleModel am in List)
            {
                if (am.ArticleID == articleID)
                {
                    article = am;
                }
            }
            return article;
        }
    }
}