Question

以下代码在vb.net和Windows Form应用程序中很不错。

Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    Dim comboSource As New Dictionary(Of String, String)()
    comboSource.Add("1", "Sunday")
    comboSource.Add("2", "Monday")
    comboSource.Add("3", "Tuesday")
    comboSource.Add("4", "Wednesday")
    comboSource.Add("5", "Thursday")
    comboSource.Add("6", "Friday")
    comboSource.Add("7", "Saturday")
    ComboBox1.DataSource = New BindingSource(comboSource, Nothing)
    ComboBox1.DisplayMember = "Value"
    ComboBox1.ValueMember = "Key"
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    Dim key As String = DirectCast(ComboBox1.SelectedItem, KeyValuePair(Of String, String)).Key
    Dim value As String = DirectCast(ComboBox1.SelectedItem, KeyValuePair(Of String, String)).Value
    MessageBox.Show(key & "   " & value)
End Sub
End Class

我想将上述代码转换为WPF应用程序。

xaml

<Window x:Class="MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid>
    <ComboBox x:Name="ComboBox1" Height="20" Width="150"/>
    <Button x:Name="Button1" Height="20" Width="80" VerticalAlignment="Top" Content="Click Me"/>
</Grid>
</Window>

vb.net

Class MainWindow 
Private Sub MainWindow_Loaded(sender As Object, e As RoutedEventArgs) Handles Me.Loaded
    Dim comboSource As New Dictionary(Of String, String)()
    comboSource.Add("1", "Sunday")
    comboSource.Add("2", "Monday")
    comboSource.Add("3", "Tuesday")
    comboSource.Add("4", "Wednesday")
    comboSource.Add("5", "Thursday")
    comboSource.Add("6", "Friday")
    comboSource.Add("7", "Saturday")
    ComboBox1.DataSource = New BindingSource(comboSource, Nothing)
    ComboBox1.DisplayMember = "Value"
    ComboBox1.ValueMember = "Key"
End Sub
Private Sub Button1_Click(sender As Object, e As RoutedEventArgs) Handles Button1.Click
    Dim key As String = DirectCast(ComboBox1.SelectedItem, KeyValuePair(Of String, String)).Key
    Dim value As String = DirectCast(ComboBox1.SelectedItem, KeyValuePair(Of String, String)).Value
    MessageBox.Show(key & "   " & value)
End Sub
End Class

链接的图片显示了错误：https://prnt.sc/kcig7j

那么，我该如何解决这些错误？

Answer 1

WinForms属性的WPF等效项如下：

DataSource -> ItemsSource
DisplayMember -> DisplayMemberPath
ValueMember -> SelectedValuePath

此外，请记住，您可以在代码隐藏或XAML中设置属性，因此您的ComboBox定义如下所示：

<ComboBox x:Name="ComboBox1" Height="20" Width="150" DisplayMemberPath="Value" SelectedValuePath="Key" />

我个人会发现在代码隐藏中设置ItemsSource属性更加容易：

Dim comboSource As New Dictionary(Of String, String)()
comboSource.Add("1", "Sunday")
comboSource.Add("2", "Monday")
comboSource.Add("3", "Tuesday")
comboSource.Add("4", "Wednesday")
comboSource.Add("5", "Thursday")
comboSource.Add("6", "Friday")
comboSource.Add("7", "Saturday")
ComboBox1.ItemsSource = comboSource

W.R.T。您的事件处理程序，对KeyValuePair(Of String, String)进行了两次强制转换；您可能应该只强制转换一次并将强制转换值存储在变量中。但是在这种情况下，您甚至不必强制转换SelectedItem。相反，您可以将sender强制转换为ComboBox并读取Text和Value属性：

Dim cmb As ComboBox = sender
MessageBox.Show($"Key: {cmb.SelectedValue}, Value: {cmb.Text}')

还要注意，您可以像使用Integer一样方便地将String用作字典键：

Dim days = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"}
Dim comboSource = days
    .Select(Function(x, index) (item:=x, index:=index+1))
    .ToDictionary(Function(x) x.index, Function(x) x.item)

在WPF应用程序中向ComboBox添加文本和值

1 个答案: