Android Question how to remember numbers

Sub Globals
    'These global variables will be redeclared each time the activity is created.
    'These variables can only be accessed from this module.
    Dim L As List
End Sub

Sub Activity_Create(FirstTime As Boolean)
    'Do not forget to load the layout file created with the visual designer. For example:
    'Activity.LoadLayout("Layout1")
    L.Initialize
End Sub

Sub Random As Int
    Dim N As Int = (Rnd (0,30) +1) ' Numerber range 1-30

    If l.Size<30 Then
        Do While L.IndexOf(N)>-1
            N  = (Rnd (0,30) +1) ' Numerber range 1-30
        Loop
        Else
            ' All number find, restart
            L.Clear
        End If
   
    L.Add(N)
    Return N
End Sub

Sub Globals
    'These global variables will be redeclared each time the activity is created.
    'These variables can only be accessed from this module.
    Dim N(30) As Boolean
End Sub

Sub Activity_Create(FirstTime As Boolean)
    'Do not forget to load the layout file created with the visual designer. For example:
    'Activity.LoadLayout("Layout1")
    For I=0 To 29
        N(I)=False
    Next
End Sub

Sub Random As Int
    Dim Count As Int = 0
    Dim Nu As Int = Rnd(0,30)
 
    For i=0 To 29
        If N(i)=True Then Count=Count+1
    Next
 
    If Count<30
        Do While N(Nu)
            Nu = Rnd(0,30)
        Loop
        N(Nu)=True
        Return (Nu+1)
    Else
        ' All number out
        Return 0
    End If
 
End Sub