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ComboBox Control

VB.Net controls are located in the Toolbox of the development environment, and you use them to create objects on a form with a simple series of mouse clicks and dragging motions. The ComboBox control , which lets the user choose one of several choices.

vb.net-combobox.jpg

The user can type a value in the text field or click the button to display a drop down list. In addition to display and selection functionality, the ComboBox also provides features that enable you to efficiently add items to the ComboBox.

Add item to combobox

ComboBox1.Items.Add("Sunday") ComboBox1.Items.Add("Monday") ComboBox1.Items.Add("Tuesday")

How to set the selected item in a comboBox

You can set which item should shown while it displaying in the form for first time.

comboBox1.Items.Add("test1") comboBox1.Items.Add("test2") comboBox1.Items.Add("test3") comboBox1.SelectedItem = "test3" or ComboBox1.SelectedItem = ComboBox1.Items(1) or comboBox1.SelectedIndex = comboBox1.FindStringExact("test3")

ComboBox SelectedItem

How to retrieve value from ComboBox

If you want to retrieve the displayed item to a string variable , you can code like this

Dim var As String var = ComboBox1.Text Or Dim item = Me.comboBox1.GetItemText(Me.comboBox1.SelectedItem) MessageBox.Show(item)

How to remove an item from ComboBox in VB.Net

You can remove items from a combobox in two ways. You can remove item at a the specified index or giving a specified item by name.

  ComboBox1.Items.RemoveAt(1)

The above code will remove the second item from the combobox.

  ComboBox1.Items.Remove("Friday")

The above code will remove the item "Friday" from the combobox.

DropDownStyle

VB.Net dropdownstyle

The DropDownStyle property specifies whether the list is always displayed or whether the list is displayed in a drop down. The DropDownStyle property also specifies whether the text portion can be edited.

  ComboBox1.DropDownStyle = ComboBoxStyle.DropDown

ComboBox DataSource Property

Programmatically Binding DataSource to ComboBox

You can populate a combo box with a DataSet in a simple way..

Consider an sql query string like...."select au_id,au_lname from authors";

Make a datasource in your program and bind it like the following...

comboBox1.DataSource = ds.Tables(0) comboBox1.ValueMember = "au_id" comboBox1.DisplayMember = "au_lname"

Combobox SelectedIndexChanged event

The SelectedIndexChanged event of a combobox fire when your selection change in the combobox. If you want some actionsg when you change the selection, you can write the code on SelectedIndexChanged event. From the following vb.net code you can understand how to set values in the SelectedIndexChanged event of a combobox. Drag and drop two combobox on the Form and copy and paste the following source code.

Public Class Form1 Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load ComboBox1.Items.Add("weekdays") ComboBox1.Items.Add("year") End Sub Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged ComboBox2.Items.Clear() If ComboBox1.SelectedItem = "weekdays" Then ComboBox2.Items.Add("Sunday") ComboBox2.Items.Add("Monday") ComboBox2.Items.Add("Tuesday") ElseIf ComboBox1.SelectedItem = "year" Then ComboBox2.Items.Add("2012") ComboBox2.Items.Add("2013") ComboBox2.Items.Add("2014") End If End Sub End Class

Output

vb.net combobox SelectedIndexChanged

VB.Net ComboBox Databinding

You can bind data to a Combobox from various resources like Dataset, List, Enum, Dictionary etc. From the following link you can study more about ... ComboBox Databinding

ComboBox Default Value

How to set a default value for a Combo Box

You can set combobox default value in VB.Net by using SelectedIndex property

comboBox1.SelectedIndex = 6

Above code set 6th item as combobox default value

ComboBox readonly

How to make a combobox read only

You can make a ComboBox readonly in VB.Net, that means a user cannot write in a combobox but he can select the given values, in two ways. By default, DropDownStyle property of a Combobox is DropDown. In this case user can enter values to combobox. When you change the DropDownStyle property to DropDownList, the Combobox will become read only and user can not enter values to combobox. Second method, if you want the combobox completely read only, you can set comboBox1.Enabled = false.

Autocomplete ComboBox

From the version Visual Studio 2005, some of the controls in VB.Net support Autocomplete feature including the ComboBox controls. From the following link you can see how to make .... Autocomplete ComboBox

ComboBox Example

The following VB.Net source code add seven days in a week to a combo box while load event of a Windows Form and display the fourth item in the combobox.




Public Class Form1
	Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
		ComboBox1.Items.Add("Sunday")
		ComboBox1.Items.Add("Monday")
		ComboBox1.Items.Add("Tuesday")
		ComboBox1.Items.Add("wednesday")
		ComboBox1.Items.Add("Thursday")
		ComboBox1.Items.Add("Friday")
		ComboBox1.Items.Add("Saturday")

		ComboBox1.SelectedItem = ComboBox1.Items(3)
	End Sub

	Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
		Dim var As String
		var = ComboBox1.Text
		MsgBox(var)
	End Sub
End Class




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