This document is a code sample in VB.NET that demonstrates how to use ListBox and ComboBox controls. It includes code to add, remove, clear items from the ListBox and ComboBox. It also shows how to insert items at a specific index in the ListBox. The form contains Label controls to display the number of items in each list. Buttons are used to trigger the different list manipulation functions.

1. VB .NET 2005 By Warawut Khangkhan
ตวอยาง การใช ListBox และ ComboBox Control
ตวอยาง การใช ListBox และ ComboBox Control
1
3 4 5 6 7 8
2
Label Control
Name: lblAmountList
9 Label Control
Name: lblAmountComboBox 11
12
Label Control
10
Name: lblIndexComboBox Label Control
Name: lblIndexListBox
13
14 15
ตาราง การก,าหนด Properties ท45สาค8ญแต:ละ Control
,
No. Control Properties Values
1 Form Name Form1
StartPosition CenterScreen
Text Example Using ListBox and ComboBox Control
2 TextBox Name TextBox1
3 Button Name Button1
Text Add Text
4 Button Name Button2
Text Clear Text
5 Button Name Button5
Text Run Number
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2. VB .NET 2005 By Warawut Khangkhan
ตาราง การก,าหนด Properties ท45สาค8ญแต:ละ Control (ต:อ)
,
No. Control Properties Values
6 NumericUpDown Name NumericUpDown1
Maximum 10
Minimum 1
7 NumericUpDown Name NumericUpDown2
Maximum 10
Minimum 1
8 NumericUpDown Name NumericUpDown3
Maximum 10
Minimum 1
9 ComboBox Name ComboBox1
DropDownStyle DropDownList
10 ListBox Name ListBox1
11 Button Name Button4
Text RemoveAt
12 Button Name Button6
Text Remove
13 TextBox Name TextBox2
14 TextBox Name TextBox3
15 Button Name Button3
Text Insert Text
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3. VB .NET 2005 By Warawut Khangkhan
Coding:
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
ComboBox1.Items.Add(TextBox1.Text.Trim)
ListBox1.Items.Add(TextBox1.Text.Trim)
lblAmountList.Text = ListBox1.Items.Count
lblAmountComboBox.Text = ComboBox1.Items.Count
TextBox1.Focus()
End Sub
Private Sub TextBox1_Enter(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.Enter
TextBox1.SelectionStart = 0
TextBox1.SelectionLength = TextBox1.Text.Length
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
ComboBox1.Items.Clear()
ListBox1.Items.Clear()
lblAmountList.Text = "0"
lblAmountComboBox.Text = "0"
lblIndexComboBox.Text = "0"
lblIndexListBox.Text = "0"
TextBox1.Focus()
End Sub
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
lblAmountList.Text = "0"
lblAmountComboBox.Text = "0"
lblIndexListBox.Text = "0"
lblIndexComboBox.Text = "0"
End Sub
Private Sub ListBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles
ListBox1.SelectedIndexChanged
lblIndexListBox.Text = ListBox1.SelectedIndex + 1
End Sub
Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles
ComboBox1.SelectedIndexChanged
lblIndexComboBox.Text = ComboBox1.SelectedIndex + 1
End Sub
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
If Convert.ToInt32(TextBox3.Text) >= 0 And Convert.ToInt32(TextBox3.Text) <= ListBox1.Items.Count Then
If Convert.ToInt32(TextBox3.Text) = 0 Then
ListBox1.Items.Insert(TextBox3.Text, TextBox2.Text)
Else
ListBox1.Items.Insert(TextBox3.Text - 1, TextBox2.Text)
End If
Else
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4. VB .NET 2005 By Warawut Khangkhan
MessageBox.Show("ระบรายการททาไมถกตอง", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information)
TextBox3.Focus()
End If
lblAmountList.Text = ListBox1.Items.Count
End Sub
Private Sub TextBox3_Enter(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox3.Enter
TextBox3.SelectionStart = 0
TextBox3.SelectionLength = TextBox3.Text.Length
End Sub
Private Sub TextBox2_Enter(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox2.Enter
TextBox2.SelectionStart = 0
TextBox2.SelectionLength = TextBox2.Text.Length
End Sub
Private Sub TextBox3_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles
TextBox3.KeyPress
If e.KeyChar < "0" Or e.KeyChar > "9" Then
e.Handled = True
End If
End Sub
Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
If ListBox1.SelectedIndex < 0 Then Exit Sub
ListBox1.Items.RemoveAt(ListBox1.SelectedIndex)
lblAmountList.Text = ListBox1.Items.Count
End Sub
Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
Dim i As Integer
If NumericUpDown1.Value > NumericUpDown2.Value Then
MessageBox.Show("Start ตองนอยกวา Stop", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information)
NumericUpDown1.Focus()
Exit Sub
End If
ListBox1.Items.Clear()
lblAmountList.Text = "0"
lblAmountComboBox.Text = "0"
lblIndexListBox.Text = "0"
lblIndexComboBox.Text = "0"
For i = NumericUpDown1.Value To NumericUpDown2.Value Step NumericUpDown3.Value
ListBox1.Items.Add("Number " & i)
Next
lblAmountList.Text = ListBox1.Items.Count
End Sub
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5. VB .NET 2005 By Warawut Khangkhan
Private Sub Button6_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button6.Click
If ListBox1.SelectedIndex < 0 Then Exit Sub
ListBox1.Items.Remove(ListBox1.SelectedItem)
lblAmountList.Text = ListBox1.Items.Count
End Sub
End Class
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