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：

 

1.  using System;using System.Collections.Generic;using System.Linq;using System.Net;using System.Windows;using System.Windows.Controls;using System.Windows.Documents;using System.Windows.Input;using System.Windows.Media;using System.Windows.Media.Animation;using System.Windows.Shapes;//添加命名空间using System.Collections.ObjectModel;using System.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 listBox1.ItemsSource = students; listBox1.DisplayMemberPath = "StudentName"; //注册选择项事件 this.listBox1.SelectionChanged += new SelectionChangedEventHandler(listBox1_SelectionChanged); } void listBox1_SelectionChanged(object sender, SelectionChangedEventArgs e) { selectedStudent = this.listBox1.SelectedItem as Student; } //删除 private void btnDel_Click(object sender, RoutedEventArgs e) { if (selectedStudent != null) { students.Remove(selectedStudent); } } //修改 private void btnEdit_Click(object sender, RoutedEventArgs e) { if (selectedStudent != null) { int myIndex = students.IndexOf(selectedStudent); students[myIndex].StudentName = "我改名了！"; } } //添加 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：当做增删改操作来修改students绑定数据源时，数据源都不能通知UI更新。 //当我们用ObservableCollection<T>作为数据绑定UI控件时：当做增删改操作来修改students绑定数据源时,Add()和Remove()操作修改的数据源能通知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:"表示一个动态数据集合，在添加项、移除项或刷新整个列表时，此集合将提供通知。" //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属性就具有更改通知的功能，这个理解是错误。ObservableCollection<T>只是针对T类型而言，并非给予了 //类成员属性更改通知的功能，要想类成员属性具有更改UI功能还得让类继承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.