对类库的学习--IComparer-优快云博客

本文介绍如何通过实现 System.Collections.IComparer 接口来自定义 ArrayList 中 Person 对象的排序方式，并提供了一个降序排列的具体实例。

最近无聊翻了翻MSDN中的.NET Framework SDK文档，随便看了看那些类库，看来看去很多空间下的接口好像重来没主动用过，于是了就找了一个接口System.Collections.IComparer学习学习，留下笔记，加深一下印象。

public partial class WebForm1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

}

        protected void Button1_Click(object sender, EventArgs e)
        {
            ArrayList list = new ArrayList();
            for (int i = 1; i < 10; i++)
            {
                Person person = new Person(i);
                list.Add(person);
            }
            foreach (Person person in list)
            {
                Response.Write(person.Value+"<br/>");
            }

System.Collections.IComparer myComparer = new PersonComparer();
//使用指定的比较器对整个 ArrayList 中的元素进行排序

            list.Sort(myComparer);
            Response.Write("After sorting.....................<br/>");
            foreach (Person personTmp in list)
            {
                Response.Write(person.Value+"<br/>");
            }

        }
    }
    public class PersonComparer : System.Collections.IComparer
    {

        public int Compare(object x, object y)
        {
            Person personX = x as Person;
            if (personX == null)
            {
                throw new ArgumentException("Error", "x");
            }
            Person personY = y as Person;
            if (personY == null)
            {
                throw new ArgumentException("Error", "y");
            }
            Int32 xy = personX.Value.CompareTo(personY.Value);
            return -xy;//降序

            //return xy 升序
        }
    }

public class Person
{

       public Person(int i)
        {
            this._value= i;
        }

        private int _value;
        public int Value
        {
            get
            {
                return _value;
            }
            set
            {
                _value= value;
            }
        }
    }