VB NET how to prevent user input in a ComboBox

Question

How do you prevent user input in a ComboBox so that only one of the items in the defined list can be selected by the user

User · Answer

Private Sub ComboBox4 KeyPress sender As Object  e As KeyPressEventArgs  Handles ComboBox4 KeyPress     e keyChar   string empty End Sub

User · Answer

this is the most simple way but it works for me with a ComboBox1 name  SOLUTION on 3 Basic STEPS   step 1    Declare a variable at the beginning of your form which will hold the original text value of the ComboBox  Example        Dim xCurrentTextValue as string   step 2   Create the event combobox1 key down  and Assign to xCurrentTextValue variable the current text of the combobox if any key diferrent than  ENTER  is pressed the combobox text value keeps the original text value  Example   Private Sub ComboBox1 KeyDown sender As Object  e As KeyEventArgs  Handles ComboBox1 KeyDown      xCurrentTextValue   ComboBox1 Text      If e KeyCode  lt  gt  Keys Enter Then         Me ComboBox1 Text   xCmbItem     End If  End Sub   step 3   Validate the when the combo text is changed if len xcurrenttextvalue   0 or is different than nothing then the combobox1 takes the xcurrenttextvalue variable value  Private Sub ComboBox1 TextChanged sender As Object  e As EventArgs  Handles ComboBox1 TextChanged     If Len xCurrentTextValue   gt  0 Then         Me ComboBox1 Text   xCurrentTextValue      End If End Sub                                                              that s it    Originally I only tried the step number 2  but I have problems when you press the DEL key and DOWN arrow key  also for some reason it didn t validate the keydown event unless I display any message box     Sorry  this is a correction on step number 2  I forgot to change the variable xCmbItem to xCurrentTextValue   xCmbItem it was used for my personal use  THIS IS THE CORRECT CODE  xCurrentTextValue   ComboBox1 Text  If e KeyCode  lt  gt  Keys Enter Then     Me ComboBox1 Text   xCurrentTextValue End If

User · Answer

Use KeyPressEventArgs   Private Sub ComboBox1 KeyPress ByVal sender As Object  ByVal e As System Windows Forms KeyPressEventArgs  Handles ComboBox1 KeyPress     e Handled   True End Sub

User · Answer

Set the ReadOnly attribute to true   Or if you want the combobox to appear and display the list of  available  values  you could handle the ValueChanged event and force it back to your immutable value

User · Answer

Using  DropDownList  for the  DropDownStyle  property of the combo box doesn t work as it changes the look and feel of the combo box   I am using Visual Studio 2019 Community Edition   Using  e Handled   True  also doesn t work either as it still allows user input   Using  False  for the  Enabled  property of the combo box also doesn t work too because it stops the user from being able to use the combo box   All of the  solutions  that have been proposed above are complete rubbish   What really works is this following code which restricts user input to certain keys such as up   down  for navigating through the list of all available choices in the combo box   suppressing all other key inputs -  Private Sub ComboBox1 KeyDown sender As Object  e As KeyEventArgs  Handles    ComboBox1 KeyDown     REM The following code is executed whenever the user has pressed     REM a key   Added on Wednesday 1st January 2020       REM Determine what key the user has pressed   Added on Wednesday     REM 1st January 2020      Select Case e KeyCode         Case Keys Down  Keys Up             REM This section is for whenever the user has pressed either             REM the arrow down key or arrow up key   Added on Wednesday             REM 1st January 2020           Case Else             REM This section is for whenever the user has pressed any             REM other key   Added on Wednesday 1st January 2020               REM Cancelling the key that the user has pressed   Added on             REM Wednesday 1st January 2020              e SuppressKeyPress   True      End Select  End Sub

User · Answer

Seeing a user banging away at a control that overrides her decisions is a sad sight   Set the control s Enabled property to False   If you don t like that then change its Items property so only one item is selectable

User · Answer

---- in form level Declaration of cbx veriable---  Dim cbx as string  Private Sub comboBox1 Enter ByVal sender As System Object  ByVal e As System EventArgs  Handles comboBox1 Enter     cbx   Me comboBox1 Text End Sub  Private Sub comboBox1 Leave ByVal sender As System Object  ByVal e As System EventArgs  Handles comboBox1 Leave     Me comboBox1 Text   cbx End Sub

User · Answer

Even if the question is marked answered  I would like to add some points to it   Set the DropDownStyle property of the combobox to DropDownList works for sure   BUT what if the drop down list is longer  the user will have to scroll it to the desired item as he has no access to keyboard    Private Sub cbostate Validating sender As Object  e As System ComponentModel CancelEventArgs  Handles cbostate Validating     If cbostate SelectedValue Is Nothing AndAlso cbostate Text  lt  gt  String Empty Then         e Cancel   True         MsgBox  Invalid State       End If End Sub   I did it like this  I wanted to restrict the user entering  random values  instead of  state  but keeping he should be able to type and search states   This validating event occurs when the control loses focus  So if user enters wrong value in combobox  It will not allow user to do anything on the form  perhaps it will not even allow to change the focus from the combobox

User · Answer

Set the DropDownStyle property of the combobox to DropDownList  This will allow only items in the list to be selected and will not allow any free-form user input

[.net] VB.NET: how to prevent user input in a ComboBox

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