Address Question

I'm wondering if anyone can answer these pretty basic OOP questions dealing with classes and memory addresses..

Public Class TestClass
Public s As String
End Class

Dim X As New TestClass
X.s = "Test 1"
Dim Y As TestClass = X
Dim Z As TestClass = X

Am I correct in saying X holds the original copy of TestClass and Y and Z are just Pointers that point to the copy of X?

So if I...
Y.s = "Test 2"

That changes the original "s" in element X right so now (X,Y,Z).s all equal "Test 2"

Now if I do a

X = Nothing

Y.s and Z.s still show the "Test 2" but now where has the Original copy that was in X gone? Are Y and Z still just pointers or does one of them now contain the original ? Im wondering because if X is no longer a object, Y and Z shouldn't be able to access it anymore right??

I'm confused.. :p

Try it:

VB Code:

Dim X As New TextBox
        X.Text = "Test 1"
        Dim Y As TextBox = X
        Dim Z As TextBox = X
        MsgBox(String.Format("Y='{0}' Z='{1}'", Y.Text, Z.Text))
 
        Y.Text = "Test 2"
        MsgBox(String.Format("X='{0}' Z='{1}'", X.Text, Z.Text))
 
        X = Nothing
        MsgBox(String.Format("Y='{0}' Z='{1}' X='{2}'", Y Is Nothing, Z Is Nothing, X Is Nothing))

I think the answer is that x,y, and z are all just pointers to the address where the class belongs. The 'original copy' is seperate and keeps track of who is referencing it and is not set to nothing, itself, until all references to it are gone or set to nothing.

Ah thanks again Edneeis, that's clears up alot.. So I guess I gotta keep tight tabs on all the pointers :)