ObservableCollection<T>泛型集合是一个经常使用的集合,表示一个动态数据集合,它可在添加、删除项目或刷新整个列表时提供通知。它继承了INotifyCollectionChanged和INotifyPropertyChanged,表示它在元素数量发生变化时,前端界面也会同步发生变化。
一、ObservableCollection<T>的定义
public class ObservableCollection<T> : Collection<T>, INotifyCollectionChanged, INotifyPropertyChanged
{
public ObservableCollection();
public ObservableCollection(List<T> list);
public ObservableCollection(IEnumerable<T> collection);
public event NotifyCollectionChangedEventHandler CollectionChanged;
protected event PropertyChangedEventHandler PropertyChanged;
public void Move(int oldIndex, int newIndex);
protected IDisposable BlockReentrancy();
protected void CheckReentrancy();
protected override void ClearItems();
protected override void InsertItem(int index, T item);
protected virtual void MoveItem(int oldIndex, int newIndex);
protected virtual void OnCollectionChanged(NotifyCollectionChangedEventArgs e);
protected virtual void OnPropertyChanged(PropertyChangedEventArgs e);
protected override void RemoveItem(int index);
protected override void SetItem(int index, T item);
}
它除了继承两个属性通知接口,还继承了一大波的接口,例如:IList, ICollection, IEnumerable, IEnumerable, IList, ICollection, IReadOnlyList, IReadOnlyCollection。所以,它拥有List集合同等的功能,而且,ObservableCollection还可以很方便的转换成List集合。
二、ObservableCollection示例
我们来创建一个ObservableCollection集合,利用之前学过的ListView控件,演示一下这个集合的功能。
前端代码
<Window x:Class="HelloWorld.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:HelloWorld"
xmlns:forms="clr-namespace:System.Windows.Forms;assembly=System.Windows.Forms"
mc:Ignorable="d" FontSize="14"
Title="WPF中文网之数据绑定 - www.wpfsoft.com" Height="350" Width="500">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition/>
<ColumnDefinition Width="200"/>
</Grid.ColumnDefinitions>
<ListView ItemsSource="{Binding Persons}" SelectedItem="{Binding Person}">
<ListView.View>
<GridView>
<GridViewColumn Header="姓名" DisplayMemberBinding="{Binding Name}" Width="60"/>
<GridViewColumn Header="年龄" DisplayMemberBinding="{Binding Age}" Width="auto"/>
<GridViewColumn Header="地址" DisplayMemberBinding="{Binding Address}" Width="auto"/>
</GridView>
</ListView.View>
</ListView>
<StackPanel Grid.Column="1" x:Name="panel" VerticalAlignment="Center" Margin="5,0">
<StackPanel Orientation="Horizontal">
<TextBlock Text="姓名:" Margin="5"/>
<TextBox Text="{Binding Person.Name,UpdateSourceTrigger=PropertyChanged}" Width="145" Height="25"/>
</StackPanel>
<StackPanel Orientation="Horizontal">
<TextBlock Text="年龄:" Margin="5"/>
<TextBox Text="{Binding Person.Age,UpdateSourceTrigger=LostFocus}" Width="145" Height="25"/>
</StackPanel>
<StackPanel Orientation="Horizontal">
<TextBlock Text="地址:" Margin="5"/>
<TextBox Text="{Binding Person.Address,UpdateSourceTrigger=Default}" Width="145" Height="25"/>
</StackPanel>
<TextBlock Margin="5" >
<Run Text="姓名:"/>
<Run Text="{Binding Person.Name}"/>
</TextBlock>
<TextBlock Margin="5" >
<Run Text="年龄:"/>
<Run Text="{Binding Person.Age}"/>
</TextBlock>
<TextBlock Margin="5" >
<Run Text="住址:"/>
<Run Text="{Binding Person.Address}"/>
</TextBlock>
<Button Content="增加用户" Click="Button_Click" Margin="5,0"/>
</StackPanel>
</Grid>
</Window>
后端代码
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.IO;
using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Threading;
namespace HelloWorld
{
public class ObservableObject : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public void RaisePropertyChanged([CallerMemberName] string propertyName = "")
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
public class Person : ObservableObject
{
private string name;
public string Name
{
get { return name; }
set { name = value;RaisePropertyChanged(); }
}
private int age;
public int Age
{
get { return age; }
set { age = value; RaisePropertyChanged(); }
}
private string address;
public string Address
{
get { return address; }
set { address = value; RaisePropertyChanged(); }
}
}
public class MainViewModel : ObservableObject
{
private Person person;
public Person Person
{
get { return person; }
set { person = value; RaisePropertyChanged(); }
}
public ObservableCollection<Person> Persons { get; set; } = new ObservableCollection<Person>();
public MainViewModel()
{
}
}
/// <summary>
/// MainWindow.xaml 的交互逻辑
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
this.DataContext = new MainViewModel();
}
private void Button_Click(object sender, RoutedEventArgs e)
{
var vm = DataContext as MainViewModel;
if (vm == null) return;
Person person = new Person();
person.Name = "新人";
person.Age = new Random().Next(1, 100);
person.Address = DateTime.Now.ToString();
vm.Persons.Add(person);
}
}
}
当增加用户时,向Persons集合中增加一个Person对象,此时,前端的ListView便会同步增加一个用户。
当前课程源码下载:(注明:本站所有源代码请按标题搜索)
文件名:054-《ObservableCollection泛型集合》-源代码
链接:https://pan.baidu.com/s/1yu-q4tUtl0poLVgmcMfgBA
提取码:wpff
——重庆教主 2023年9月14日