How to bind button to method in VB.net - wpf

Question

I am doing some research online to find out how to do this but I have fallen short so far. I think there is a knowledge gap that I have to overcome.
I have a wpf button that when clicked would execute a sub inside of the object it is bound too.
I would like to know how to get the button to execute exampleObject.displayMessage().
VB.NET
Private Sub Window_Loaded(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded
Dim exObject As New exampleObject
Grid1.DataContext = exObject
End Sub
Public Class exampleObject
Public ReadOnly Property testMessage As String
Get
Return "this is a test"
End Get
End Property
Public Sub displayMessage()
MsgBox(testMessage)
End Sub
End Class
WPF
<Window x:Class="Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="300" Width="300">
<Grid>
<Grid Name="Grid1">
<Button Content="Button" Name="Button1"/>
</Grid>
</Grid>
</Window>

Answer 1

To execute a method you need to use Commands. Refer below implementation.
<Grid>
<Grid>
<Grid Name="Grid1">
<Button Content="Button" Name="Button1" Command="{Binding TestCommand}"/>
</Grid>
</Grid>
</Grid>
Class MainWindow
Private Sub Window_Loaded(sender As Object, e As RoutedEventArgs)
Dim exObject As New exampleObject
Grid1.DataContext = exObject
End Sub
End Class
Public Class exampleObject
Private m_TestCommand As ICommand
Public Property TestCommand As ICommand
Get
Return m_TestCommand
End Get
Set(ByVal value As ICommand)
m_TestCommand = value
End Set
End Property
Public Sub New()
m_TestCommand = New DelegateCommand(AddressOf displayMessage, AddressOf CandisplayMessage)
End Sub
Public Sub displayMessage(ByVal param As Object)
MsgBox(testMessage)
End Sub
Private Function CandisplayMessage(ByVal param As Object) As Boolean
Return True
End Function
Public ReadOnly Property testMessage As String
Get
Return "this is a test"
End Get
End Property
End Class
Public Class DelegateCommand
Implements ICommand
Private m_canExecute As Func(Of Object, Boolean)
Private m_executeAction As Action(Of Object)
Private m_canExecuteCache As Boolean
Public Event CanExecuteChanged(ByVal sender As Object, ByVal e As System.EventArgs) Implements ICommand.CanExecuteChanged
Public Sub New(ByVal executeAction As Action(Of Object), ByVal canExecute As Func(Of Object, Boolean))
Me.m_executeAction = executeAction
Me.m_canExecute = canExecute
End Sub
Public Function CanExecute(ByVal parameter As Object) As Boolean Implements ICommand.CanExecute
Dim temp As Boolean = m_canExecute(parameter)
If m_canExecuteCache <> temp Then
m_canExecuteCache = temp
RaiseEvent CanExecuteChanged(Me, New EventArgs())
End If
Return m_canExecuteCache
End Function
Public Sub Execute(ByVal parameter As Object) Implements ICommand.Execute
m_executeAction(parameter)
End Sub
End Class
I have got the Delegate command from http://www.paulspatterson.com/mvvm-and-wpf-for-vb-net-%E2%80%93-part-5-%E2%80%93-delegating-commands/. That site gives very detailed information.