在表单中动态添加多个ComboBox并读取添加的ComboBoxes的输入？

I need to add variable numbers of ComboBoxes in my form and later I need to read the inputs from the ComboBoxes.

我需要在我的表单中添加可变数量的ComboBox，稍后我需要从ComboBox中读取输入。

I have this code-

我有这个代码 -

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        Dim n As Integer = Int(QsnNo.Text)
        Dim i As Integer = 0
        Do While i <= n
            ComboGen(i)
            i = i + 1
        Loop
    End Sub

    Public Function ComboGen(ByVal n As Integer)
        Dim newCombo As New ComboBox
        With newCombo
            .Name = "MyComboBox" & n.ToString
            .Left = 10
            .Top = 10 + (20 * n) + 20
            .Width = 70
            .Height = 20
            .Items.Add("A")
            .Items.Add("B")
            .Visible = True
        End With
        Me.Controls.Add(newCombo)
        Return 0
    End Function

And I can add ComboBoxes. But I want to read the inputs from the ComboBoxes later when I Click on Button2. That I can't. How can I do that?

我可以添加ComboBoxes。但是我想在稍后单击Button2时读取ComboBox的输入。我不能。我怎样才能做到这一点？

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles 

    Button2.Click
            TextBox1.Text = MyComboBox1.selectedItem
        End Sub

I need output like this.

我需要像这样的输出。

3 个解决方案

#1

You can add event handler to each combobox you create. This way you can easily use all comboboxes properties at runtime.

您可以为您创建的每个组合框添加事件处理程序。这样，您可以在运行时轻松使用所有组合框属性。

Full example:

完整示例：

    Public Class Form1
    Dim intTop As Integer = 1
    Dim strText As String
    Dim cmb As ComboBox

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        AddNewTextBox()
        AddHandler cmb.GotFocus, AddressOf cmb_Click
    End Sub

    Public Function AddNewTextBox() As ComboBox
        cmb = New ComboBox
        Me.Controls.Add(cmb)
        cmb.Top = intTop * 25
        cmb.Left = 10
        cmb.Text = "ComboBox " & Me.intTop.ToString
        intTop = intTop + 1
        Return cmb
    End Function

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        TextBox1.Text = strText
    End Sub

    Private Sub cmb_Click(sender As Object, e As EventArgs)
        strText = sender.Text
    End Sub

End Class

#2

You can access controls by its name:

您可以通过其名称访问控件：

MsgBox(Me.Controls("MyComboBox" & intYourComboBoxNumber).SelectedItem)

#3

What you can do is declare a List(Of ComboBox) in your form's class;

你可以做的是在你的表单类中声明一个List（Of ComboBox）;

Private ComboBoxes As New List(Of ComboBox)

What you then can do is add your dynamically-created ComboBox to that list when it's created;

您可以做的是在创建时将动态创建的ComboBox添加到该列表中;

ComboBoxes.Add(newCombo)

To call upon this later, as long as it's not disposed, you can do, for example:

要稍后调用它，只要它没有被处理掉，你可以这样做，例如：

TextBox1.Text = ComboBoxes(0).SelectedItem ' Rather than 1, do 0 - zero-based index.

Also; note that ComboGen should be a Sub - not a Function as you're always returning 0 and never getting a "proper" result - however, you could encapsulate your code in a Try/Catch to return a Boolean, True if succeeded, False if not.

也;请注意，ComboGen应该是一个Sub而不是一个函数，因为你总是返回0并且永远不会得到“正确”的结果 - 但是，你可以将你的代码封装在Try / Catch中以返回一个布尔值，如果成功则返回True，如果成功则返回False不。

Public Function ComboGen(ByVal n As Integer) As Boolean
    Try ' Start of your Try/Catch block.
        Dim newCombo As New ComboBox
        With newCombo
            .Name = "MyComboBox" & n.ToString
            .Left = 10
            .Top = 10 + (20 * n) + 20
            .Width = 70
            .Height = 20
            .Items.Add("A")
            .Items.Add("B")
            .Visible = True
        End With
        ComboBoxes.Add(newCombo) ' Add your ComboBox to the list.
        Me.Controls.Add(newCombo)
        Return True
    Catch ex As Exception ' Catch your exception.
        Return False
    End Try ' End the Try/Catch block.
End Function

#1