Android Question Class not returning view

[jvetterli]

Hi all,

I'm struggling to create a class who should act as a custom button (panel with label view):

Class gets initialized including the needed width and height:

Public Sub Initialize(pEventname As String, pModule As Object, iWidth As Int, iHeight As Int)
   
    module    = pModule
    Eventname = pEventname
    BkgPanel.Initialize("pnl")
   
    btnWidth = iWidth
    btnHeight = iHeight
   
End Sub

Getting the view back as panel, at this time I'm trying to set the dimensions of the panel and label:

Public Sub AsPanel As Panel
   
    Dim LblH As Int = btnWidth/3 + 5dip
    Dim PicSize As Int = btnHeight - LblH - 5dip
   
    BkgPanel.Left = 0
    BkgPanel.Top = 0
    BkgPanel.Width = btnWidth
    BkgPanel.Height = btnHeight
    BkgPanel.Color = Colors.Gray
   
    BtnLabel.Initialize("pnl")
    BtnLabel.Text = "TestTest"
    BtnLabel.TextColor = Colors.White
    BtnLabel.Gravity= Bit.Or(Gravity.CENTER_HORIZONTAL, Gravity.TOP)
   
    BkgPanel.AddView(BtnLabel,5dip,10dip + PicSize,btnWidth-10dip,LblH)
   
    Return BkgPanel
   
End Sub

In the main activity I call the class as follows:

Sub Globals

    Private Panel1 As Panel 'main Layout
    Private Button1 As Button 'main Layout
   
    Private pnlButton As Panel
    Dim classBtn As CLbutton
   
End Sub

Sub Activity_Create(FirstTime As Boolean)

    Activity.LoadLayout("main")
   
    classBtn.Initialize("clbClick",Me,150dip,150dip)
   
    pnlButton = classBtn.AsPanel
    Panel1.AddView(pnlButton,0,0,150dip,150dip)
   
   
End Sub

Unfortunately the call to classBtn.AsPanel returns an error :
java.lang.NullPointerException: Attempt to write to field 'int anywheresoftware.b4a.BALayout$LayoutParams.left' on a null object reference


Could someone please show me how to fix this problem, sample solution is attached, thanks.

 

[klaus]

Instead of using a Standard Class you should use CustomView Class.
You might have a look at chapter 12 Class modules in the B4A User's Guide, where CustomViews are explained in detail with examples.

 

[jvetterli]

Thanks for the quick reply and the hint to the User's Guide, should have looked there in the beginning as the explanations and examples are really helpful!