ComboBox Items
The Items property is used to add and work with
items in a ComboBox. We can add items to a ComboBox at design-time from
Properties Window by clicking on Items Collection as you can see in Figure 5.
Figure 5
When you click on the Collections, the String
Collection Editor window will pop up where you can type strings. Each line added
to this collection will become a ComboBox item. I add four items as you can see
from Figure 6.
Figure 6
The ComboBox looks like Figure 7.
Figure 7
You can add same items at run-time by using the
following code snippet.
ComboBox1.Items.Add("Mahesh
Chand")
ComboBox1.Items.Add("Mike
Gold")
ComboBox1.Items.Add("Praveen
Kumar")
ComboBox1.Items.Add("Raj
Beniwal")
Getting All Items
To get all items, we use the Items property and
loop through it to read all the items. The following code snippet loops through
all items and adds item contents to a StringBuilder and displays in a MessageBox.
Dim
sb As New
System.Text.StringBuilder
For Each item
In ComboBox1.Items
sb.Append(item)
sb.Append("
")
Next
MessageBox.Show(sb.ToString())
Selected Text and Item
Text property is used to set and get text of a
ComboBox. The following code snippet sets and gets current text of a ComboBox.
ComboBox1.Text =
"Mahesh Chand"
MessageBox.Show(ComboBox1.Text)
We can also get text associated with currently
selected item by using Items property.
Dim
selectedItem As
String = ComboBox1.Items(ComboBox1.SelectedIndex)
Why the value of ComboBox.SelectedText is Empty?
SelectedText property gets and sets the selected text in a ComboBox only when a
ComboBox has focus on it. If the focus moves away from a ComboBox, the value of
SelectedText will be an empty string. To get current text in a ComboBox when it
does not have focus, use Text property.
DataSource
DataSource property is used to get and set a data source to a ComboBox. The data
source can be a collection or object that implements IList interface such as an
array, a collection, or a DataSet. The following code snippet binds an
enumeration converted to an array to a ComboBox.
ComboBox1.DataSource = System.Enum.GetValues(GetType(ComboBoxStyle))
DropDownStyle
DropDownStyle property is used to gets and sets the style of a ComboBox. It is a
type of ComboBoxStyle enumeration.
The
ComboBoxStyle enumeration has following three values.
·
Simple
- List is always visible and the text portion is editable.
·
DropDown
â€" List is displayed by clicking the down arrow and that the text portion is
editable.
·
DropDownList
- List is displayed by clicking the down arrow and that the text portion is not
editable.
The
following code snippet sets the DropDownStyle property of a ComboBox to
DropDownList.
ComboBox1.DropDownStyle =
ComboBoxStyle.DropDownList
DroppedDown
If
set true, the dropped down portion of the ComboBox is displayed. By default,
this value is false.
Sorting Items
The Sorted property set to true, the ComboBox
items are sorted. The following code snippet sorts the ComboBox items.
ComboBox1.Sorted =
True
Find Items
The FindString method is used to find a string
or substring in a ComboBox. The following code snippet finds a string in a
ComboBox and selects it if found.
Private
Sub FindStringButton_Click(ByVal
sender As System.Object,
_
ByVal e As System.EventArgs)
Handles FindStringButton.Click
Dim index As
Integer = ComboBox1.FindString(TextBox1.Text)
If (index < 0) Then
MessageBox.Show("Item
not found.")
TextBox1.Text =
String.Empty
Else
ComboBox1.SelectedIndex = index
End If
End
Sub