Android Question manipulating panels from an array

67biscuits · Aug 27, 2026

I am looking for a way to manipulate the visible status of panels by using an array (list) in order to do so.
I have tried this but the app crashes:

B4X:

Dim pnls As List = Array As Panel(pnlClient, pnlTime, pnlMtrl, pnlEquip, pnlTasks, pnlNotes)

sub buttonPushed
      Dim b As Button = Sender
     Dim t As Int = b.Tag
           Log(pnls.Size)  'puts the number 6 on the log screen
     For x = 0 To pnls.Size - 1
        pnls.Get(x).As (Panel).Visible = False
    Next
end sub

Any help would be appreciated

LucaMs · Aug 28, 2026

The code you posted is correct (except for the space between "As" and "("), but I assume you misspelled that here), so the error must be elsewhere.
You should post the error message, otherwise it's impossible to help you.

67biscuits · Aug 28, 2026

I've copied it all in back in to demonstrate and to include the error msg.

declared sub class_globals:

B4X:

    Dim pnls As List = Array As Panel(pnlClient, pnlTime, pnlMtrl, pnlEquip, pnlTasks, pnlNotes)

in a button activated Sub:

B4X:

    Dim b As Button = Sender
    Dim t As Int = b.Tag
    
    For x = 0 To pnls.Size - 1
        pnls.Get(x).As(Panel).Visible = False
    Next
    pnls.get(t).as(Panel).visible = True

** Activity (main) Create (first time) **
** Activity (main) Resume **
Error occurred on line: 321 (B4XMainPage)
java.lang.ClassCastException: anywheresoftware.b4a.objects.PanelWrapper cannot be cast to android.view.ViewGroup
at b4a.example.b4xmainpage._openpanel_click(b4xmainpage.java:956)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:732)
at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:348)
at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:255)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:157)
at anywheresoftware.b4a.BA.raiseEvent(BA.java:209)
at anywheresoftware.b4a.objects.ViewWrapper$1.onClick(ViewWrapper.java:80)
at android.view.View.performClick(View.java:7448)
at android.view.View.performClickInternal(View.java:7425)
at android.view.View.access$3600(View.java:810)
at android.view.View$PerformClick.run(View.java:28309)
at android.os.Handler.handleCallback(Handler.java:938)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7701)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:610)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:952)

Sagenut · Aug 28, 2026

Try this

B4X:

Sub Globals
    'These global variables will be redeclared each time the activity is created.
    Private pnlClient As B4XView
    Private pnlTime As B4XView
    Private pnlMtrl As B4XView
    Private pnlEquip As B4XView
    Private pnlTasks As B4XView
    Private pnlNotes As B4XView
    Private pnls As List
End Sub

Sub Activity_Create(FirstTime As Boolean)
    Activity.LoadLayout("Layout")
    pnls.Initialize
    pnls.AddAll(Array(pnlClient, pnlTime, pnlMtrl, pnlEquip, pnlTasks, pnlNotes))
End Sub

Sub Button1_Click
    For x = 0 To pnls.Size -1
        pnls.Get(x).As(Panel).Visible = False
    Next
End Sub

Eventually post your full code (it would be better a project to test with the issue) to check what it's not working.
Or use an ARRAY instead of a List if you have a small fixed number of item like in your case

B4X:

Sub Globals
    'These global variables will be redeclared each time the activity is created.
    Private pnlClient As B4XView
    Private pnlTime As B4XView
    Private pnlMtrl As B4XView
    Private pnlEquip As B4XView
    Private pnlTasks As B4XView
    Private pnlNotes As B4XView
    Private pnls() As Panel
End Sub

Sub Activity_Create(FirstTime As Boolean)
    Activity.LoadLayout("Layout")
    pnls = Array as Panel(pnlClient, pnlTime, pnlMtrl, pnlEquip, pnlTasks, pnlNotes)
End Sub

Sub Button1_Click
    For x = 0 To pnls.Length - 1
        pnls(x).Visible = False
    Next
End Sub

67biscuits · Aug 28, 2026

Except for a detail here and there I have essentially have your first example. i will double check the details and fix and retry. The main difference being I dim the panels as panels as opposed to B4Xview. I have far less issues and program for my own devices exclusively.
Thanks for the help Sagenut. I adjusted the details in your first example. (if I'm right, its just the way I used AddAll assembling the pnls list. Anyway, it works, and I will study it a little more to grasp a better understanding. thanks so much

klaus · Aug 28, 2026

What error do you get and in which line ?

Cableguy · Aug 28, 2026

Also, may I add... being this a Question, why did the OP taged it as "Code Snippet"?

LucaMs · Aug 28, 2026

Cableguy said:
why did the OP taged it as "Code Snippet"?

For fun

67biscuits · Saturday at 1:10 AM

klaus said:
What error do you get and in which line ?

(taken from the post back a few posts...)
java.lang.ClassCastException: anywheresoftware.b4a.objects.PanelWrapper cannot be cast to android.view.ViewGroup

I got it when I made the pnls[] elements invisible. More aptly, tried to.

klaus · Saturday at 2:02 PM

Sorry, i missed this.
As Sagenut already suggested, it would be easier to help you if you posted a small project showing the problem.

Sagenut · Saturday at 3:20 PM

67biscuits said:
(taken from the post back a few posts...)
java.lang.ClassCastException: anywheresoftware.b4a.objects.PanelWrapper cannot be cast to android.view.ViewGroup

I got it when I made the pnls[] elements invisible. More aptly, tried to.

I think that this happen because you set the array in this way

B4X:

Array as Panel(.......)

Try setting it with

B4X:

Array(.......)

Did you test my code example?

67biscuits · Sunday at 12:48 PM

Sagenut said:
I think that this happen because you set the array in this way

B4X:

Array as Panel(.......)

Try setting it with

B4X:

Array(.......)

Did you test my code example?

I did change my code to reflect your example, and it fixed the problem. Thanks again Sagenut

67biscuits · Sunday at 12:50 PM

klaus said:
Sorry, i missed this.
As Sagenut already suggested, it would be easier to help you if you posted a small project showing the problem.

Not a problem Klaus, I have fixed and I am hoping to have learned from the issue. : )

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