Question

我有一个表单，我在其中显示另一个表单：

if (headerText == "")
{
    MhrtTemplateColumn objMhrtTemplateColumn = 
            new MhrtTemplateColumn("", lstUnusedChannelTags);
    objMhrtTemplateColumn.ShowDialog();
}
else
{
    MhrtTemplateColumn objMhrtTemplateColumn = 
            new MhrtTemplateColumn(ChannelDesc, lstUnusedChannelTags, CurrentTag);
    objMhrtTemplateColumn.ShowDialog();
}

这些是重载的构造函数：

public MhrtTemplateColumn(string channelDescription, List<string> channelTags)
{
    InitializeComponent();
    this.ChannelDescription = channelDescription;
    this.ChannelTags = new List<string>();
    this.ChannelTags.Clear();            
    this.ChannelTags = channelTags;
}
public MhrtTemplateColumn(string channelDescription, List<string> channelTags, string CurrentChannelTag)
{
    InitializeComponent();
    this.ChannelDescription = channelDescription;
    this.ChannelTags = new List<string>();
    this.ChannelTags.Clear();
    this.ChannelTags = channelTags;
    this.CurrentChannelTag = CurrentChannelTag;
}

这是MhrtTemplateColumn的Window_Loaded事件：

private void Window_Loaded(object sender, RoutedEventArgs e)
{
    txtChannelDescription.Text = ChannelDescription;
    if (CurrentChannelTag != null && CurrentChannelTag != "")
    {
        if(ChannelTags.Contains(CurrentChannelTag) == false)
            ChannelTags.Add(CurrentChannelTag);
        cmbChannelTag.ItemsSource = null;
        cmbChannelTag.ItemsSource = ChannelTags;
        cmbChannelTag.SelectedValue = CurrentChannelTag;
    }
    else
    {
        cmbChannelTag.ItemsSource = null;
        cmbChannelTag.ItemsSource = ChannelTags;
        cmbChannelTag.SelectedIndex = 0;
    }           
}

我的问题是当执行else块时，新项目会添加到列表中。关闭表单并使用if块中的代码再次显示该表单后，列表仍然具有先前添加的新项目。为什么呢？

Answer 1

this.ChannelTags = new List<string>();
this.ChannelTags.Clear();            
this.ChannelTags = channelTags;

我认为使用此代码您正试图复制channelTags？如果是这样，这是如何做到的：

this.ChannelTags = channelTags.ToList();

您的代码只会创建一个空列表，清除它，然后将其抛弃并将channelTags分配给该字段。

列表项目未清除

1 个答案: