ListBox 不显示绑定数据 [英] ListBox does not display the binding data

问题描述

在我的 Xaml 中，我有这个，

In my Xaml i have this,

<ComboBox x:Name="masterCB" HorizontalAlignment="Left" Margin="5,127,0,0" VerticalAlignment="Top" Width="106" Height="22" Background="White" ItemsSource="{Binding Masters}" FontSize="11" SelectedIndex="{Binding Action}"/>
        <Label Content="Select Action:" HorizontalAlignment="Left" VerticalAlignment="Top" Height="26" Width="116" Margin="0,151,0,0" Background="{x:Null}" FontWeight="Bold"/>

<ListBox x:Name="actionBox" HorizontalAlignment="Left" Height="250" VerticalAlignment="Top" Width="116" Margin="5,177,0,0" ScrollViewer.HorizontalScrollBarVisibility="Disabled" 
            ItemsSource="{Binding ActionList}" AlternationCount="2" MouseDoubleClick="actionBox_DoubleClick">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <Grid Background="{x:Null}">
                        <TextBlock Text="{Binding}" TextTrimming="WordEllipsis" TextWrapping="Wrap" Height="40" FontSize="11" />
                    </Grid>
                </DataTemplate>
            </ListBox.ItemTemplate>
            <ListBox.ItemContainerStyle>
                <Style TargetType="{x:Type ListBoxItem}">
                    <Style.Triggers>
                        <Trigger Property="ItemsControl.AlternationIndex" Value="1">
                            <Setter Property="Background" Value="Silver"/>
                        </Trigger>
                    </Style.Triggers>
                </Style>
            </ListBox.ItemContainerStyle>

在我的数据类中，我有这个，

In my data class i have this,

private List<String> actionList;
public int Action 
   { 
       get{return this.action;} 
       set
       {
           action = value;
           populateActionList();
       } 
   }
 public List<String> ActionList
   {
       get { return actionList; }
       set { this.actionList = value; }
   private void populateActionList()
   {
       if (this.action == 0)
       {
           actionList = new List<String> { 
       "Chinese",
       "Indian",
       "Malay",
       "Indian",
       };
       if (this.action == 1)
       {
           actionList = new List<String> { 
       "Dog",
       "Cats",
       "Pigs",
       "Horses",
       "Fish",
       "Lion"};
       }
   }

当我执行打印行时，我的 actionList 已更改，但 ListBox 项未设置为我的 actionList.只想知道 UI 不更新的原因和原因?我在某处读到您必须更改为 DataContext 和 ObservableCollections，但我尝试了那个，但它仍然没有更新.有谁知道为什么?

When i do a printline, my actionList is changed, but the ListBox item is not set to my actionList. Would just like to know why and how come the UI does not update? I read somewhere that you would have to change to DataContext and ObservableCollections but i tried that one out and it still does not update. Does anyone know why?

推荐答案

将您的代码更改为以下内容，将达到您的预期

Changing your code to the following, will do what you expect

private ObservableCollection<String> _actionList; 

public ObservableCollection<String> ActionList {
  get { 
    if (_actionList == null) {
      _actionList = new ObservableCollection<String>();
    }

    return actionList; 
  }
}

private void populateActionList(){
  if (this.action == 0) {
    ActionList.Clear();

    ActionList.Add("Chinese");
    ActionList.Add("Indian");
    ActionList.Add("Malay");
    ActionList.Add("Indian");
  }

  if (this.action == 1){
    ActionList.Clear();

    ActionList.Add("Dog");
    ActionList.Add("Cats");
    ActionList.Add("Pigs");
    ActionList.Add("Horses");
    ActionList.Add("Fish");
    ActionList.Add("Lion");
  }
}

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