ByVal does work not correctly in VB.NET - vb.net

Question

I have a code in VB.NET like this:
' This code will sort array data
Public Sub SelectionSort(ByVal array as ArrayList)
For i as Integer = 0 To array.Count -1
Dim index = GetIndexMinData(array, i)
Dim temp = array(i)
array(i) = array(index)
array(index) = temp
Next
End Sub
Public Function GetIndexMinData(ByVal array As ArrayList, ByVal start As Integer) As Integer
Dim index As Integer
Dim check As Integer = maxVal
For i As Integer = start To Array.Count - 1
If array(i) <= check Then
index = i
check = array(i)
End If
Next
Return index
End Function
' This code will sort array data
Public Sub SelectionSortNewList(ByVal array As ArrayList)
Dim temp As New ArrayList
' Process selection and sort new list
For i As Integer = 0 To array.Count - 1
Dim index = GetIndexMinData(array, 0)
temp.Add(array(index))
array.RemoveAt(index)
Next
End Sub
Private Sub btnProcess_Click(sender As System.Object, e As System.EventArgs) Handles btnProcess.Click
Dim data as new ArrayList
data.Add(3)
data.Add(5)
data.Add(1)
SelectionSort(data)
SelectionSortNewList(data)
End Sub
When I run this code, in the btnProcess event click, variable "data" is array = {3,5,1}. By SelectionSort(data) procedure, variable data is changed. Item in variable data have sorted by that procedure, so when SelectionSortNewList(data) is run, array "data" have sorted became {1,3,5}. Why does it happen?
Although I have used "Byval parameter" in SelectionSort and SelectionSortNewList, I don't want variable data to be changed when it pass to SelectionSort.

Answer 1

Even if you use a ByVal on an object, the properties of the object can be modified.
The instance of the object cannot be modified but not its properties.
Example:
Public Class Cars
Private _Make As String
Public Property Make() As String
Get
Return _Make
End Get
Set(ByVal value As String)
_Make = value
End Set
End Property
End Class
If I pass the class as ByVal;
Private sub Test(ByVal MyCar as Car)
MyCar.Make = "BMW"
End Sub
The value of the property will change as you're pointing to the same object and modifying its property.