我正在尝试编写一个绑定类的演示继承接口。 这是接口代码:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace App1
{
public interface BaseClass
{
string AAA { get; set; }
}
}
这是Page的代码隐藏:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
// The Blank Page item template is documented at https://go.microsoft.com/fwlink/?LinkId=402352&clcid=0x409
namespace App1
{
/// <summary>
/// An empty page that can be used on its own or navigated to within a Frame.
/// </summary>
public sealed partial class MainPage : Page, INotifyPropertyChanged
{
public BaseClass BC;
public static MainPage MP;
public MainPage()
{
this.InitializeComponent();
MP = this;
BC = new ChildClass();
}
public event PropertyChangedEventHandler PropertyChanged;
protected void RaisePropertyChanged(string name)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
}
public class ChildClass : BaseClass
{
string _AAA = "123";
public string AAA
{
get { return _AAA; }
set { _AAA = value; MP.RaisePropertyChanged("AAA"); }
}
}
private void Button_Click(object sender, RoutedEventArgs e)
{
BC.AAA = "456";
}
}
}
最后这里是XAML:
<Page
x:Class="App1.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:App1"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<Grid>
<Grid.RowDefinitions>
<RowDefinition></RowDefinition>
<RowDefinition></RowDefinition>
</Grid.RowDefinitions>
<TextBlock Text="{x:Bind BC.AAA,Mode=OneWay}"></TextBlock>
<Button Grid.Row="1" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Click="Button_Click">123</Button>
</Grid>
</Page>
运行程序后,它将成功显示默认的AAA字符串。但是,当我单击按钮时,它无法将文本更改为“456”。 我想知道是否存在INotifyPropertyChanged问题。但我不知道它有什么问题。 你能告诉我这有什么问题吗?谢谢。
2个错误:
第一:
请注意,ChidClass
调用MP.RaisePropertyChanged("AAA")
,而不是BaseClass
。所以,而不是像BC一样宣布BC
public BaseClass BC;
做
public ChildClass BC;
代替。
第二:属性AAA
不属于MainPage
类,它属于ChildClass
,所以不是在INotifyPropertyChanged
中实现MainPage
,而是在ChildClass
中实现它:
public class ChildClass : BaseClass, INotifyPropertyChanged
{
string _AAA = "123";
public string AAA
{
get { return _AAA; }
set { _AAA = value; RaisePropertyChanged("AAA"); }
}
public event PropertyChangedEventHandler PropertyChanged;
protected void RaisePropertyChanged(string name)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
}
}
这应该工作。
编辑:你犯的第一个错误,如果是故意,因为你想将UI绑定到这个界面,那么抱歉,你不能这样做。
为什么?因为,要实现这一点,您需要在该接口中引发INotifyPropertyChanged
事件,但c#中的接口(当前为c#7.3)不允许您执行任何默认实现,这意味着您无法编写任何代码来引发该事件。话虽如此,不久的将来,C#8.0将具备此功能。你能等到那么吗?