Ensure there is at least one item selected : ListBox « Windows Presentation Foundation « VB.Net

1. VB.Net
2. Windows Presentation Foundation
3. ListBox

Ensure there is at least one item selected

     
        
<Window x:Class="WpfApplication1.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="WPF" Height="300" Width="300">
    <StackPanel>
        <ListBox FontSize="16" Height="150" Margin="5" Name="listBox1" SelectionMode="Extended">
            <ListBoxItem>List Item 1</ListBoxItem>
            <ListBoxItem>List Item 2</ListBoxItem>
            <ListBoxItem>List Item 3</ListBoxItem>
        </ListBox>
        <StackPanel HorizontalAlignment="Center" Orientation="Horizontal">
            <Label Content="_New item text:" VerticalAlignment="Center" Target="{Binding ElementName=textBox}"  />
            <TextBox Margin="5" Name="textBox" MinWidth="120" />            
        </StackPanel>
        <StackPanel HorizontalAlignment="Center" Orientation="Horizontal">
            <Button Click="btnAddListItem_Click" Content="Add Item" IsDefault="True" Margin="5" Name="btnAddListItem" />
            <Button Click="btnDeleteListItem_Click" Content="Delete Items" Margin="5" Name="btnDeleteListItem" />
            <Button Click="btnSelectAll_Click" Content="Select All" Margin="5" Name="btnSelectAll" />
        </StackPanel>
    </StackPanel>
</Window>
//File:Window.xaml.vb
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Media

Namespace WpfApplication1
  Public Partial Class Window1
    Inherits Window
    Public Sub New()
      InitializeComponent()
    End Sub
    Private Sub btnAddListItem_Click(sender As Object, e As RoutedEventArgs)
      If textBox.Text.Length = 0 Then
        MessageBox.Show("Enter text to add to the list.", Title)
      Else
        Dim item As New ListBoxItem()
        item.Content = textBox.Text
        item.IsSelected = True
        item.HorizontalAlignment = HorizontalAlignment.Center
        item.FontWeight = FontWeights.Bold
        item.FontFamily = New FontFamily("Tahoma")

        listBox1.Items.Add(item)

        textBox.Clear()
        textBox.Focus()
      End If
    End Sub

    Private Sub btnDeleteListItem_Click(sender As Object, e As RoutedEventArgs)
      If listBox1.SelectedItems.Count = 0 Then
        MessageBox.Show("Select list items to delete.", Title)
      Else
        While listBox1.SelectedItems.Count > 0
          listBox1.Items.Remove(listBox1.SelectedItems(0))
        End While
      End If
    End Sub
    Private Sub btnSelectAll_Click(sender As Object, e As RoutedEventArgs)
      listBox1.SelectAll()
    End Sub
  End Class
End Namespace

   
    
    
    
    
  

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