如何在自定義類上實現依賴對象/屬性？

Question

這裏是我的Person類：

public class Person 
{ 
    private string _lastName; 

    public string LastName 
    { 
     get { return _lastName; } 
     set { _lastName = value; } 

    } 
}//close class 

這是我的XAML：

 <StackPanel> 
     <TextBox x:Name="txtLastName" 
       Height="50" Width="300" 
       DataContext="{Binding ElementName=_this, Path=PersonObject}" 
       Text="{Binding Path=LastName}" /> 

     <Button Height="50" Width="100" x:Name="btnChangeValue" Content="Change Value" Click="btnChangeValue_Click"/> 
    </StackPanel> 

這裏是我的XAML.CS

public partial class ClassDependency : Window 
{ 
    public Person objPerson = new Person(); 
    public ClassDependency() 
    { 
     objPerson.LastName = "testing..."; 
     InitializeComponent(); 

    } 

    public Person PersonObject 
    { 
     get { return objPerson; } 
     set { objPerson = value; } 
    } 

    private void btnChangeValue_Click(object sender, RoutedEventArgs e) 
    { 
     objPerson.LastName = "New value after click...."; 
    } 
}//close class 

我的問題是：點擊 「btnChangeValue」 它之後在我的代碼後面更改Last Name，但它不反映我的文本框「txtLastName」。我怎樣才能解決這個問題？？？我應該在我的xaml.cs文件中實現依賴屬性？我也試過，但沒用。

public static readonly DependencyProperty PersonObjectProperty = DependencyProperty.Register("PersonObject", typeof(object), typeof(ClassDependency)); 
    public Person PersonObject 
    { 
     get { return (Person)GetValue(PersonObjectProperty); } 
     set { SetValue(PersonObjectProperty, value); } 
    } 

我該怎麼辦？請指點..

Answer 1

試試這個：

public class Person : INotifyPropertyChanged 
{ 
    public event PropertyChangedEventHandler PropertyChanged; 

    private string _lastName; 

    public string LastName 
    { 
     get { return _lastName; } 
     set 
     { 
      _lastName = value; 
      if (PropertyChanged != null) 
      { 
       PropertyChanged(this, new PropertyChangedEventArgs("LastName")); 
      } 
     } 
    } 
} 

這樣，框架得到通知的屬性發生變化時。請參閱INotifyPropertyChanged Interface。

Answer 2

與您的代碼的問題是，你是不是引發PropertyChanged事件，所以用戶界面是不知道的值更改的，對你的依賴的setter屬性提高PropertyChanged事件，如下圖所示：

public class Person : INotifyPropertyChanged 
{ 
    private string _lastName; 

    public string LastName 
    { 
     get { return _lastName; } 
     set 
     { 
      _lastName = value; 
      if (PropertyChanged != null) 
      { 
       PropertyChanged(this, new PropertyChangedEventArgs("LastName")); 
      } 
     } 
    } 
}