Selected index changed of listbox in WPF using MVVM and icommand

See more:

VB

WPF

MVVM

Hi All,

I have a WPF Application in which I am binding an ObservableCollection of integers to a ListBox in MVVM architecture, it is binding it properly, but when I select an item from the ListBox, I want to retrieve that item (or integer) and bind it to a label.

Can anybody please help me how to get SelectedIndex changed in my ViewModel using binding?

My View

<Window x:Class="DiceGameForm"
   xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:dicegamens="clr-namespace:DiceGame"
    mc:Ignorable="d"
    Title="DiceGameForm" Height="500" Width="800" WindowStartupLocation="CenterScreen">
    <Window.DataContext>
        <dicegamens:DiceGameViewModel x:Name="_diceGameViewModel" 
           ImageSourcePath="C:\Users\Abdul.Aleem\Desktop\DiceGame\DiceGame\die1.png">
        </dicegamens:DiceGameViewModel>
    </Window.DataContext>
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition/>
            <ColumnDefinition Width="76.988"/>
        </Grid.ColumnDefinitions>
        <ListBox x:Name="lbHistory" Margin="1.988,40.96,10,10" Grid.Column="1" FontSize="21.333" 
                 FontWeight="Bold" FontStyle="Italic" 
                 ItemsSource="{Binding Items, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" 
                 SelectedItem="{Binding SelectedItem, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"
                  />
        <Button x:Name="cmdClearHistory" Content="Clear" VerticalAlignment="Top" Grid.Column="1" Margin="0,13,10,0" HorizontalAlignment="Right" Width="65"/>
        <Button x:Name="cmdRollDice" Content="Roll Dice" VerticalAlignment="Top" Margin="10,13,0,0" HorizontalAlignment="Left" Width="65" Command="{Binding ClickSaveCommand, Mode=OneWay}"/>
        <Image x:Name="imgDie" Margin="10,42.97,10,10" Source="{Binding ImageSourcePath}" />
    </Grid>
</Window>

And my viewmodel

Imports System.ComponentModel
Imports System.Configuration
Imports System.Collections.ObjectModel

Public Class DiceGameViewModel
    Implements INotifyPropertyChanged, IDataErrorInfo

    Private _imageSourcePath As String
    Public Property ImageSourcePath() As String
        Get
            Return _imageSourcePath
        End Get
        Set(ByVal value As String)
            _imageSourcePath = value

            NotifyPropertyChanged("ImageSourcePath")
        End Set
    End Property

    Private _items As ObservableCollection(Of Integer)
    Public Property Items() As ObservableCollection(Of Integer)
        Get
            Return _items
        End Get
        Set(ByVal value As ObservableCollection(Of Integer))
            _items = value
            NotifyPropertyChanged("Items")
        End Set
    End Property

   
    Private _selectedItem As Integer
    Public Property SelectedItem() As Integer
        Get
            Return _selectedItem
        End Get
        Set(ByVal value As Integer)
            _selectedItem = value
            NotifyPropertyChanged("SelectedItem")
        End Set
    End Property


    Sub New()
        _items = New ObservableCollection(Of Integer)()

        _imageSourcePath = DisplayNewDiceValue(GetRandom(1, 6))
    End Sub

    Public ReadOnly Property [Error] As String Implements IDataErrorInfo.Error
        Get

        End Get
    End Property

    Default Public ReadOnly Property Item(columnName As String) As String Implements IDataErrorInfo.Item
        Get

        End Get
    End Property

    Private _clickSaveCommand As ICommand
    Public ReadOnly Property ClickSaveCommand() As ICommand
        Get
            Return If(_clickSaveCommand, (InlineAssignHelper(_clickSaveCommand, New RollDiceCommand(Sub() CmdClickRollDice(), True))))
        End Get
    End Property

    Private Shared Function InlineAssignHelper(Of T)(ByRef target As T, ByVal value As T) As T
        target = value
        Return value
    End Function

    Private Sub CmdClickRollDice()
        ' 'Clear history selection
        ''lbHistory.SelectedItem = Nothing

        Dim i As Integer = GetRandom(1, 6)
        DisplayNewDiceValue(i)
        DisplayHistory(i)
    End Sub


    Public Event PropertyChanged(sender As Object, e As PropertyChangedEventArgs) Implements INotifyPropertyChanged.PropertyChanged

    Private Sub NotifyPropertyChanged(propertyName As String)
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
    End Sub

    ''' <summary>
    ''' Display the new image of the dice on the form
    ''' </summary>
    ''' <param name="value"></param>
    Private Function DisplayNewDiceValue(value As Integer) As String
        If (value <= 0) Then
            value = 1
        End If

        Dim ImageFolder As String = ConfigurationSettings.AppSettings.Get("ImageFolder")
        Dim sPic As String = String.Format("{0}die{1}.png", ImageFolder, value.ToString)

        Return sPic
    End Function

    ''' <summary>
    ''' Get a new random number
    ''' </summary>
    ''' <param name="Min">Minimum number to return</param>
    ''' <param name="Max">Maximum number to return</param>
    ''' <returns>integer value of random between min and max</returns>
    Private Function GetRandom(ByVal Min As Integer, ByVal Max As Integer) As Integer

        Static Generator As System.Random = New System.Random()
        Return Generator.Next(Min, Max)

    End Function

    Private Sub DisplayHistory(value As Integer)

        _items.Add(value)

    End Sub
End Class

What I have tried:

I am trying all options on the code and searching using google while testing the application