vb.net - combo box always select the first value

问题

Good day, Can anyone help me with this problem. I have two a combo box for months(01-12) for monthstart and monthend. Now, everytime I select October(10), the value it show is 01. Sorry. I am new in vb.

Is there any alternative way to do this? Any suggestions?

Thanks.

 Private Sub ValueComboxformonth()
    Dim comboSource As New Dictionary(Of String, String)()
    comboSource.Add("01", "January")
    comboSource.Add("02", "February")
    comboSource.Add("03", "March")
    comboSource.Add("04", "April")
    comboSource.Add("05", "May")
    comboSource.Add("06", "June")
    comboSource.Add("07", "July")
    comboSource.Add("08", "August")
    comboSource.Add("09", "September")
    comboSource.Add("10", "October")
    comboSource.Add("11", "November")
    comboSource.Add("12", "December")

    cmbAppliedMonthStart.DataSource = New BindingSource(comboSource, Nothing)
    cmbAppliedMonthStart.DisplayMember = "Value"
    cmbAppliedMonthStart.ValueMember = "Key"

    cmbAppliedMonthEnd.DataSource = New BindingSource(comboSource, Nothing)
    cmbAppliedMonthEnd.DisplayMember = "Value"
    cmbAppliedMonthEnd.ValueMember = "Key"

End Sub


 Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
    ValueComboxformonth()
    Dim monthkeystart As String = DirectCast(cmbAppliedMonthStart.SelectedItem, KeyValuePair(Of String, String)).Key
    Dim monthvaluestart As String = DirectCast(cmbAppliedMonthStart.SelectedItem, KeyValuePair(Of String, String)).Value

    Dim monthkeyend As String = DirectCast(cmbAppliedMonthEnd.SelectedItem, KeyValuePair(Of String, String)).Key
    Dim monthvalueend As String = DirectCast(cmbAppliedMonthEnd.SelectedItem, KeyValuePair(Of String, String)).Value
End Sub

The value of monthkeystart is 01
The value of monthvaluestart is January

回答1:

This is due to you calling the ValueComboxformonth method before reading the values. That method resets the datasource for the combo-boxes, and it defaults to the first value.

Try moving that call to the constructor (New method) of the form.

Public Sub New()
    ...
    ValueComboxformonth()
End Sub

来源：https://stackoverflow.com/questions/34207453/vb-net-combo-box-always-select-the-first-value

标签

vb.net

winforms

combobox