对Silverlight中ObservableCollection自己的一点理解

            本篇学习了ObservableCollection<T>相关知识，因为在项目开发中我碰到一些问题，后来发现时我的理解偏差！所以做下笔记！

（一）代码：

using Sy<a href="http://code.js-code.com/tag/stem/" target="_blank" class="keywords">stem</a>; using Sy<a href="http://code.js-code.com/tag/stem/" target="_blank" class="keywords">stem</a>.Collection<a href="http://code.js-code.com/tag/s/" target="_blank" class="keywords">s.</a>Generi<a href="http://code.js-code.com/tag/c/" target="_blank" class="keywords">c;</a> using Sy<a href="http://code.js-code.com/tag/stem/" target="_blank" class="keywords">stem</a>.Linq; using Sy<a href="http://code.js-code.com/tag/stem/" target="_blank" class="keywords">stem</a>.Net; using Sy<a href="http://code.js-code.com/tag/stem/" target="_blank" class="keywords">stem</a>.Windows; using Sy<a href="http://code.js-code.com/tag/stem/" target="_blank" class="keywords">stem</a>.Window<a href="http://code.js-code.com/tag/s/" target="_blank" class="keywords">s.</a>Controls; using Sy<a href="http://code.js-code.com/tag/stem/" target="_blank" class="keywords">stem</a>.Window<a href="http://code.js-code.com/tag/s/" target="_blank" class="keywords">s.</a>Documents; using Sy<a href="http://code.js-code.com/tag/stem/" target="_blank" class="keywords">stem</a>.Window<a href="http://code.js-code.com/tag/s/" target="_blank" class="keywords">s.</a>Input; using Sy<a href="http://code.js-code.com/tag/stem/" target="_blank" class="keywords">stem</a>.Window<a href="http://code.js-code.com/tag/s/" target="_blank" class="keywords">s.</a>Media; using Sy<a href="http://code.js-code.com/tag/stem/" target="_blank" class="keywords">stem</a>.Window<a href="http://code.js-code.com/tag/s/" target="_blank" class="keywords">s.</a>Media.Animation; using Sy<a href="http://code.js-code.com/tag/stem/" target="_blank" class="keywords">stem</a>.Window<a href="http://code.js-code.com/tag/s/" target="_blank" class="keywords">s.</a>Shapes; //<a href="http://code.js-code.com/tag/tianjia/" target="_blank" class="keywords">添加</a>命名空间 using Sy<a href="http://code.js-code.com/tag/stem/" target="_blank" class="keywords">stem</a>.Collection<a href="http://code.js-code.com/tag/s/" target="_blank" class="keywords">s.</a>Ob<a href="http://code.js-code.com/tag/je/" target="_blank" class="keywords">je</a>ctModel; using Sy<a href="http://code.js-code.com/tag/stem/" target="_blank" class="keywords">stem</a>.ComponentModel; namespace CatalogTest <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> public partial class ObservableCollectionVSList : UserControl <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> ObservableCollection<<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent> <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dents = new ObservableCollection<<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent>(<a href="http://code.js-code.com/tag/" target="_blank" class="keywords">);</a> //List<<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent> <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dents = new List<<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent>(<a href="http://code.js-code.com/tag/" target="_blank" class="keywords">);</a> <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent <a href="http://code.js-code.com/tag/SELE/" target="_blank" class="keywords">SELE</a>cted<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent = null; public ObservableCollectionVSList() <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> InitializeComponent(<a href="http://code.js-code.com/tag/" target="_blank" class="keywords">);</a> thi<a href="http://code.js-code.com/tag/s/" target="_blank" class="keywords">s.</a>Loaded += new RoutedEventHandler(ObservableCollectionVSList_Loaded<a href="http://code.js-code.com/tag/" target="_blank" class="keywords">);</a> } void ObservableCollectionVSList_Loaded(ob<a href="http://code.js-code.com/tag/je/" target="_blank" class="keywords">je</a>ct sender,RoutedEventArgs <a href="http://code.js-code.com/tag/E/" target="_blank" class="keywords">E)</a> <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent1 = new <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent() <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentID = "001",<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentName = "<a href="http://code.js-code.com/tag/zhangsan/" target="_blank" class="keywords">张三</a>" }; <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent2 = new <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent() <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentID = "002",<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentName = "<a href="http://code.js-code.com/tag/lisi/" target="_blank" class="keywords">李四</a>" }; <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent3 = new <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent() <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentID = "003",<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentName = "<a href="http://code.js-code.com/tag/wangwu/" target="_blank" class="keywords">王五</a>" }; <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent<a href="http://code.js-code.com/tag/s/" target="_blank" class="keywords">s.</a>Add(<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent1<a href="http://code.js-code.com/tag/" target="_blank" class="keywords">);</a> <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent<a href="http://code.js-code.com/tag/s/" target="_blank" class="keywords">s.</a>Add(<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent2<a href="http://code.js-code.com/tag/" target="_blank" class="keywords">);</a> <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent<a href="http://code.js-code.com/tag/s/" target="_blank" class="keywords">s.</a>Add(<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent3<a href="http://code.js-code.com/tag/" target="_blank" class="keywords">);</a> //绑定 list<a href="http://code.js-code.com/tag/Box/" target="_blank" class="keywords">Box</a>1.Items<a href="http://code.js-code.com/tag/sourc/" target="_blank" class="keywords">sourc</a>e = <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dents; list<a href="http://code.js-code.com/tag/Box/" target="_blank" class="keywords">Box</a>1.Displa<a href="http://code.js-code.com/tag/ym/" target="_blank" class="keywords">ym</a>emberPath = "<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentName"; //<a href="http://code.js-code.com/tag/zhuce/" target="_blank" class="keywords">注册</a>选择项事件 thi<a href="http://code.js-code.com/tag/s/" target="_blank" class="keywords">s.</a>list<a href="http://code.js-code.com/tag/Box/" target="_blank" class="keywords">Box</a>1.<a href="http://code.js-code.com/tag/SELE/" target="_blank" class="keywords">SELE</a>ctionChanged += new <a href="http://code.js-code.com/tag/SELE/" target="_blank" class="keywords">SELE</a>ctionChangedEventHandler(list<a href="http://code.js-code.com/tag/Box/" target="_blank" class="keywords">Box</a>1_<a href="http://code.js-code.com/tag/SELE/" target="_blank" class="keywords">SELE</a>ctionChanged<a href="http://code.js-code.com/tag/" target="_blank" class="keywords">);</a> } void list<a href="http://code.js-code.com/tag/Box/" target="_blank" class="keywords">Box</a>1_<a href="http://code.js-code.com/tag/SELE/" target="_blank" class="keywords">SELE</a>ctionChanged(ob<a href="http://code.js-code.com/tag/je/" target="_blank" class="keywords">je</a>ct sender,<a href="http://code.js-code.com/tag/SELE/" target="_blank" class="keywords">SELE</a>ctionChangedEventArgs <a href="http://code.js-code.com/tag/E/" target="_blank" class="keywords">E)</a> <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> <a href="http://code.js-code.com/tag/SELE/" target="_blank" class="keywords">SELE</a>cted<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent = thi<a href="http://code.js-code.com/tag/s/" target="_blank" class="keywords">s.</a>list<a href="http://code.js-code.com/tag/Box/" target="_blank" class="keywords">Box</a>1.<a href="http://code.js-code.com/tag/SELE/" target="_blank" class="keywords">SELE</a>ctedItem as <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent; } //<a href="http://code.js-code.com/tag/shanchu/" target="_blank" class="keywords">删除</a> private void btnDel_Click(ob<a href="http://code.js-code.com/tag/je/" target="_blank" class="keywords">je</a>ct sender,RoutedEventArgs <a href="http://code.js-code.com/tag/E/" target="_blank" class="keywords">E)</a> <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> if <a href="http://code.js-code.com/tag/SELE/" target="_blank" class="keywords">(SELE</a>cted<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">!=</a> null) <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent<a href="http://code.js-code.com/tag/s/" target="_blank" class="keywords">s.</a>Remove<a href="http://code.js-code.com/tag/SELE/" target="_blank" class="keywords">(SELE</a>cted<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent<a href="http://code.js-code.com/tag/" target="_blank" class="keywords">);</a> } } //<a href="http://code.js-code.com/tag/xiugai/" target="_blank" class="keywords">修改</a> private void btnEdit_Click(ob<a href="http://code.js-code.com/tag/je/" target="_blank" class="keywords">je</a>ct sender,RoutedEventArgs <a href="http://code.js-code.com/tag/E/" target="_blank" class="keywords">E)</a> <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> if <a href="http://code.js-code.com/tag/SELE/" target="_blank" class="keywords">(SELE</a>cted<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">!=</a> null) <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> int myIndex = <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent<a href="http://code.js-code.com/tag/s/" target="_blank" class="keywords">s.</a>IndexOf<a href="http://code.js-code.com/tag/SELE/" target="_blank" class="keywords">(SELE</a>cted<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent<a href="http://code.js-code.com/tag/" target="_blank" class="keywords">);</a> <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dents[myIndex].<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentName = "我改名了！"; } } //<a href="http://code.js-code.com/tag/tianjia/" target="_blank" class="keywords">添加</a> private void btnAdd_Click(ob<a href="http://code.js-code.com/tag/je/" target="_blank" class="keywords">je</a>ct sender,RoutedEventArgs <a href="http://code.js-code.com/tag/E/" target="_blank" class="keywords">E)</a> <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent = new <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent() <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentID="009",<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentName="Joetao"}; <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent<a href="http://code.js-code.com/tag/s/" target="_blank" class="keywords">s.</a>Add(<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent<a href="http://code.js-code.com/tag/" target="_blank" class="keywords">);</a> } } public class <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> public <a href="http://code.js-code.com/tag/Stri/" target="_blank" class="keywords">Stri</a>ng <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentID <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> get; set; } public <a href="http://code.js-code.com/tag/Stri/" target="_blank" class="keywords">Stri</a>ng <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentName <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> get; set; } } //分别采用 ObservableCollection<<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent>与List<<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent>作为绑定数据源 //当我们用List<T>作为数据源绑定UI控件时：当做增删改操作来<a href="http://code.js-code.com/tag/xiugai/" target="_blank" class="keywords">修改</a><a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dents绑定数据源时，数据源都不能<a href="http://code.js-code.com/tag/tongzhi/" target="_blank" class="keywords">通知</a>UI更新。 //当我们用ObservableCollection<T>作为数据绑定UI控件时：当做增删改操作来<a href="http://code.js-code.com/tag/xiugai/" target="_blank" class="keywords">修改</a><a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dents绑定数据源时,Add()和Remove()操作<a href="http://code.js-code.com/tag/xiugai/" target="_blank" class="keywords">修改</a>的数据源能<a href="http://code.js-code.com/tag/tongzhi/" target="_blank" class="keywords">通知</a>UI更新，而改操作不能更新UI. // //这一点正说明了MSDN上对ObservableCollection<T>类介绍:"表示<a href="http://code.js-code.com/tag/yige/" target="_blank" class="keywords">一个</a>动态数据集合，在<a href="http://code.js-code.com/tag/tianjia/" target="_blank" class="keywords">添加</a>项、移除项或刷新整个列表时，此集合将提供<a href="http://code.js-code.com/tag/tongzhi/" target="_blank" class="keywords">通知</a>。" //我<a href="http://code.js-code.com/tag/zaichuli/" target="_blank" class="keywords">在处理</a>这个问题理解偏差： //在一开始的时候我对这句话：“实现您自己的集合之前，应<a href="http://code.js-code.com/tag/kao/" target="_blank" class="keywords">考</a>虑使用 ObservableCollection<T> 类，该类具有 INotifyCollectionChanged 和 INotifyPropertyChanged 的内置实现。“ //被我理解为了只要用了ObservableCollection<T>，这个类集合以及类集合中的所有成员<a href="http://code.js-code.com/tag/shuxing/" target="_blank" class="keywords">属性</a>就具有更改<a href="http://code.js-code.com/tag/tongzhi/" target="_blank" class="keywords">通知</a>的<a href="http://code.js-code.com/tag/gongneng/" target="_blank" class="keywords">功能</a>，这个理解是<a href="http://code.js-code.com/tag/cuowu/" target="_blank" class="keywords">错误</a>。ObservableCollection<T>只是针对T类型而言，并非给予了 //<a href="http://code.js-code.com/tag/leichengyuan/" target="_blank" class="keywords">类成员</a><a href="http://code.js-code.com/tag/shuxing/" target="_blank" class="keywords">属性</a>更改<a href="http://code.js-code.com/tag/tongzhi/" target="_blank" class="keywords">通知</a>的<a href="http://code.js-code.com/tag/gongneng/" target="_blank" class="keywords">功能</a>，要想<a href="http://code.js-code.com/tag/leichengyuan/" target="_blank" class="keywords">类成员</a><a href="http://code.js-code.com/tag/shuxing/" target="_blank" class="keywords">属性</a>具有更改UI<a href="http://code.js-code.com/tag/gongneng/" target="_blank" class="keywords">功能</a>还得让类继承INotifyPropertyChanged接口，并用 (NotifyCollectionChangedEventArgs) 的事件数据报告有关集合更改的特性的信息 }

（二）实现类成员更改通知UI:

          要想实现类属性值修改，我们必须修改student类，如下：

  public class <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dent : INotifyPropertyChanged <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> private <a href="http://code.js-code.com/tag/Stri/" target="_blank" class="keywords">Stri</a>ng <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentID; public <a href="http://code.js-code.com/tag/Stri/" target="_blank" class="keywords">Stri</a>ng <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentID <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> get <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> return <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentID; } set <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentID = value; NotifyPropertyChange("<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentID"<a href="http://code.js-code.com/tag/" target="_blank" class="keywords">);</a> } } private <a href="http://code.js-code.com/tag/Stri/" target="_blank" class="keywords">Stri</a>ng <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentName; public <a href="http://code.js-code.com/tag/Stri/" target="_blank" class="keywords">Stri</a>ng <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentName <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> get <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> return <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentName; } set <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> <a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentName = value; NotifyPropertyChange("<a href="http://code.js-code.com/tag/stu/" target="_blank" class="keywords">stu</a>dentName"<a href="http://code.js-code.com/tag/" target="_blank" class="keywords">);</a> } } public event PropertyChangedEventHandler PropertyChanged; private void NotifyPropertyChange(<a href="http://code.js-code.com/tag/Stri/" target="_blank" class="keywords">Stri</a>ng property<a href="http://code.js-code.com/tag/Name/" target="_blank" class="keywords">Name)</a> <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> if (PropertyChanged <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">!=</a> null) <a href="http://code.js-code.com/tag/" target="_blank" class="keywords">{</a> PropertyChanged(this,new PropertyChangedEventArgs(property<a href="http://code.js-code.com/tag/Name/" target="_blank" class="keywords">Name)</a><a href="http://code.js-code.com/tag/" target="_blank" class="keywords">);</a> } } }

（三）总结：

          本篇学习了 ObservableCollection<T>与List<T>作为绑定数据源的不同，实例充分说明了 ObservableCollection<T>在Silverlight中作为绑定数据源的优势！ 并例举了自己最初对ObservableCollection<T>的误解。并说明了怎样实现类属性成员的修改更改UI的实现方法！这里绑定可以是OneTime,OneWay,TwoWay.具体    理解可以看我的另一篇文章Silverlight中OneTime,TwoWay及INotifyPropertyChanged 接口的理解