Question

我想问一些关于组合框和文本框的帮助。所以这就是问题，我一直试图弄清楚如何使用组合框将值分配到文本框中，这就是它的样子

If yearlevel.SelectedItem = "Nursery" Then
    txtamount.Text = "1000"
    If yearlevel.SelectedItem = "Kinder" Then
        txtamount.Text = "2000"
    End If
End If

我想要发生的是，当我选择“幼儿园”时，“1000”会自动出现在文本框中。

Answer 1

If yearlevel.SelectedItem = "Nursery" Then
  txtamount.Text = "1000"
ElseIf yearlevel.SelectedItem = "Kinder" Then
  txtamount.Text = "2000"
End If

如果这不符合您的要求，请解释您的问题简而言之。

Answer 2

使用SelectedIndexChanged事件：

Private Sub yearLevel_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles yearLevel.SelectedIndexChanged
    Select Case yearLevel.SelectedItem.ToString
        Case "Nursery" : txtAmount.Text = "1000"
        Case "Kinder" : txtAmount.Text = "2000"
    End Select
End Sub

为了使其更加动态和简单，当您将项目添加到组合框中时，将其添加为包含文本和金额的对象，然后当selectedindexchanged发生时，只需将selectedobject转换回您自己的对象并使用金额值：

   Private Structure YearLevelItemStruct
    Private _Text As String
    Private _Amount As Double
    Public ReadOnly Property Text() As String
        Get
            Return Me._Text
        End Get
    End Property
    Public ReadOnly Property Amount() As Double
        Get
            Return Me._Amount
        End Get
    End Property
    Public Sub New(ByVal Text As String, ByVal Amount As Double)
        Me._Text = Text
        Me._Amount = Amount
    End Sub
    Public Overrides Function ToString() As String
        Return _Text
    End Function
End Structure


Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    loaditems()
End Sub
Sub loaditems()
    yearLevel.Items.Clear()
       yearLevel.Items.Add(New YearLevelItemStruct("Nursery", 1000))
    yearLevel.Items.Add(New YearLevelItemStruct("Kinder", 2000))
End Sub

Private Sub yearLevel_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles yearLevel.SelectedIndexChanged
    txtAmount.Text = DirectCast(yearLevel.SelectedItem, YearLevelItemStruct).Amount.ToString
End Sub

当然，如果你已经拥有某些列表中的所有项目或某些具有ToString（）的对象的数组，那么你就不需要创建一个自己的结构来保存该对象。如果您的对象没有ToString（），那么您可以使用组合框：s .DisplayMember =“some_property_that_returns_a_string”。因为如果它没有暴露ToString（并且你不使用.DisplayMamber），那么组合框将填充类型的名称而不是文本。

如何使用组合框在文本框中插入值

2 个答案: