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="/tag/stem/" target="_blank" class="keywords">stem</a>; using Sy<a href="/tag/stem/" target="_blank" class="keywords">stem</a>.Collections.Generic; using Sy<a href="/tag/stem/" target="_blank" class="keywords">stem</a>.Linq; using Sy<a href="/tag/stem/" target="_blank" class="keywords">stem</a>.Net; using Sy<a href="/tag/stem/" target="_blank" class="keywords">stem</a>.Windows; using Sy<a href="/tag/stem/" target="_blank" class="keywords">stem</a>.Windows.Controls; using Sy<a href="/tag/stem/" target="_blank" class="keywords">stem</a>.Windows.Documents; using Sy<a href="/tag/stem/" target="_blank" class="keywords">stem</a>.Windows.Input; using Sy<a href="/tag/stem/" target="_blank" class="keywords">stem</a>.Windows.Media; using Sy<a href="/tag/stem/" target="_blank" class="keywords">stem</a>.Windows.Media.Animation; using Sy<a href="/tag/stem/" target="_blank" class="keywords">stem</a>.Windows.Shapes; //<a href="/tag/tianjia/" target="_blank" class="keywords">添加</a>命名空间 using Sy<a href="/tag/stem/" target="_blank" class="keywords">stem</a>.Collections.ObjectModel; using Sy<a href="/tag/stem/" target="_blank" class="keywords">stem</a>.ComponentModel; namespace CatalogTest { public partial class ObservableCollectionVSList : UserControl { ObservableCollection<Student> students = new ObservableCollection<Student>(); //List<Student> students = new List<Student>(); Student selectedStudent = null; public ObservableCollectionVSList() { InitializeComponent(); this.Loaded += new RoutedEventHandler(ObservableCollectionVSList_Loaded); } void ObservableCollectionVSList_Loaded(object sender,RoutedEventArgs e) { Student student1 = new Student() { StudentID = "001",StudentName = "张三" }; Student student2 = new Student() { StudentID = "002",StudentName = "李四" }; Student student3 = new Student() { StudentID = "003",StudentName = "王五" }; students.Add(student1); students.Add(student2); students.Add(student3); //绑定 list<a href="/tag/Box/" target="_blank" class="keywords">Box</a>1.ItemsSource = students; list<a href="/tag/Box/" target="_blank" class="keywords">Box</a>1.<a href="/tag/dis/" target="_blank" class="keywords">dis</a>playMemberPath = "StudentName"; //<a href="/tag/zhuce/" target="_blank" class="keywords">注册</a>选择项事件 this.list<a href="/tag/Box/" target="_blank" class="keywords">Box</a>1.SelectionChanged += new SelectionChangedEventHandler(list<a href="/tag/Box/" target="_blank" class="keywords">Box</a>1_SelectionChanged); } void list<a href="/tag/Box/" target="_blank" class="keywords">Box</a>1_SelectionChanged(object sender,SelectionChangedEventArgs e) { selectedStudent = this.list<a href="/tag/Box/" target="_blank" class="keywords">Box</a>1.SelectedItem as Student; } //<a href="/tag/shanchu/" target="_blank" class="keywords">删除</a> private void btnDel_Click(object sender,RoutedEventArgs e) { if (selectedStudent != null) { students.Remove(selectedStudent); } } //<a href="/tag/xiugai/" target="_blank" class="keywords">修改</a> private void btnEdit_Click(object sender,RoutedEventArgs e) { if (selectedStudent != null) { int myIndex = students.IndexOf(selectedStudent); students[myIndex].StudentName = "我改名了！"; } } //<a href="/tag/tianjia/" target="_blank" class="keywords">添加</a> private void btnAdd_Click(object sender,RoutedEventArgs e) { Student student = new Student() { StudentID="009",StudentName="Joetao"}; students.Add(student); } } public class Student { public string StudentID { get; set; } public string StudentName { get; set; } } //分别采用 ObservableCollection<Student>与List<Student>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="/tag/xiugai/" target="_blank" class="keywords">修改</a>students绑定数据源时，数据源都不能<a href="/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="/tag/xiugai/" target="_blank" class="keywords">修改</a>students绑定数据源时,Add()和Remove()操作<a href="/tag/xiugai/" target="_blank" class="keywords">修改</a>的数据源能<a href="/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="/tag/yige/" target="_blank" class="keywords">一个</a>动态数据集合，在<a href="/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="/tag/tongzhi/" target="_blank" class="keywords">通知</a>。" //我在处理这个问题理解偏差： //在一开始的时候我对这句话：“实现您自己的集合之前，应考虑使用 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="/tag/shuxing/" target="_blank" class="keywords">属性</a>就具有更改<a href="/tag/tongzhi/" target="_blank" class="keywords">通知</a>的<a href="/tag/gongneng/" target="_blank" class="keywords">功能</a>，这个理解是<a href="/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="/tag/leichengyuan/" target="_blank" class="keywords">类成员</a><a href="/tag/shuxing/" target="_blank" class="keywords">属性</a>更改<a href="/tag/tongzhi/" target="_blank" class="keywords">通知</a>的<a href="/tag/gongneng/" target="_blank" class="keywords">功能</a>，要想<a href="/tag/leichengyuan/" target="_blank" class="keywords">类成员</a><a href="/tag/shuxing/" target="_blank" class="keywords">属性</a>具有更改UI<a href="/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 Student : INotifyPropertyChanged { private string studentID; public string StudentID { get { return studentID; } set { studentID = value; NotifyPropertyChange("StudentID"); } } private string studentName; public string StudentName { get { return studentName; } set { studentName = value; NotifyPropertyChange("StudentName"); } } public event PropertyChangedEventHandler PropertyChanged; private void NotifyPropertyChange(string propertyName) { if (PropertyChanged != null) { PropertyChanged(this,new PropertyChangedEventArgs(propertyName)); } } }

（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