blocks|key|1258646|text|将ReadOnly属性设置为true。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1258647|或者，如果您希望组合框出现并显示“可用”值列表，您可以处理ValueChanged事件并强制它返回到不可变值。|1258648|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

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.

blocks|key|1043764|text|看到用户猛烈地敲击覆盖其决策的控件，这是一个令人悲伤的场景。将控件的Enabled属性设置为False。如果你不喜欢这样，那就改变它的Items属性，这样只有一个项目是可选择的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1043765|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

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.

blocks|key|1258684|text|使用KeyPressEventArgs，|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1258685|Private+Sub+ComboBox1_KeyPress(ByVal+sender+As+Object,+ByVal+e+As+System.Windows.Forms.KeyPressEventArgs)+Handles+ComboBox1.KeyPress
++++e.Handled+=+True
End+Sub|code-block|syntax|javascript|1258686|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Use KeyPressEventArgs,

<pre><code>Private Sub ComboBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles ComboBox1.KeyPress
 e.Handled = True
End Sub
</code></pre>

blocks|key|1043779|text|Private+Sub+ComboBox4_KeyPress(sender+As+Object,+e+As+KeyPressEventArgs)+Handles+ComboBox4.KeyPress
++++e.keyChar+=+string.empty
End+Sub|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1043780|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>Private Sub ComboBox4_KeyPress(sender As Object, e As KeyPressEventArgs) Handles ComboBox4.KeyPress
 e.keyChar = string.empty
End Sub
</code></pre>

blocks|key|1258716|text|-在cbx的表格级声明中可验证|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1258717|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|code-block|syntax|javascript|1258718|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

---- in form level Declaration of cbx veriable---

<pre><code>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
</code></pre>

blocks|key|1258752|text|使用组合框的'DropDownStyle‘属性的'DropDownList’不起作用，因为它改变了组合框的外观。我使用的是Visual+Studio+2019社区版。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1258753|使用'e.Handled+=+True‘也不起作用，因为它仍然允许用户输入。对组合框的'Enabled‘属性使用'False’也不起作用，因为它会阻止用户使用组合框。|1258754|上面提出的所有“解决方案”都完全是垃圾。真正起作用的是下面的代码，它限制用户输入某些键，如向上/向下(用于在组合框中所有可用选项的列表中导航)，抑制所有其他键输入：|1258755|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|code-block|syntax|javascript|1258756|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|O|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|P|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

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:-

<pre><code>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
</code></pre>

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?

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

Visual Studio

Windows

如何防止用户在ComboBox中输入，以便用户只能选择已定义列表中的一项？

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