Android Question Why "Dim clv As CustomListView = Activity.GetView(0).tag" not work?

[Filippo]

Hi,

Why this line code (see title) does not work(see error message)?
But the line code "Dim btn As Button = Activity.GetView(1)" yes?
With other customview it works too.

Sub Activity_Create(FirstTime As Boolean)
    Activity.LoadLayout("Layout")
    
    Dim clv As CustomListView = Activity.GetView(0).tag
    Log("clv.IsInitialized=" & clv.IsInitialized)
    
    Dim btn As Button =  Activity.GetView(1)   
    Log("btn.IsInitialized=" & btn.IsInitialized)
End Sub

error message:

*** Service (starter) Create ***
** Service (starter) Start **
** Activity (main) Create, isFirst = true **
main_activity_create (java line: 353)
java.lang.ClassCastException: java.lang.String cannot be cast to b4a.example3.customlistview
at b4a.example.main._activity_create(main.java:353)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:213)
at b4a.example.main.afterFirstLayout(main.java:105)
at b4a.example.main.access$000(main.java:17)
at b4a.example.main$WaitForLayout.run(main.java:83)
at android.os.Handler.handleCallback(Handler.java:938)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loopOnce(Looper.java:201)
at android.os.Looper.loop(Looper.java:288)
at android.app.ActivityThread.main(ActivityThread.java:7880)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:568)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1045)

 

[Alexander Stolte]

Because in the tag is not the xclv. The solution:

[B4X] how to get a xCustomListView from a container if it was generated dynamically

I have a form with a xCustomListView, I now add this form to another xCustomListView as an item. How can I access this dynamic added xCustomListView now? This is not working: As these conventions are rather new, they are not used by some popular custom views such as xCLV. You can set the base...

www.b4x.com

 

[Filippo]

Because in the tag is not the xclv. The solution:

[B4X] how to get a xCustomListView from a container if it was generated dynamically

I have a form with a xCustomListView, I now add this form to another xCustomListView as an item. How can I access this dynamic added xCustomListView now? This is not working: As these conventions are rather new, they are not used by some popular custom views such as xCLV. You can set the base...

www.b4x.com

Yes, this can be a solution, but why an extra solution only for the xCustomListview?
With all other customviews it works without problems.

 

[Alexander Stolte]

With all other customviews it works without problems.

All other CustomViews that were either updated to this new standard, or were created after 20. May 2020 this became standard. And the xCLV is not one of them.

[B4X] How to get <custom view here> from <CLV or any other container>

This is a common question and for a good reason. Custom views classes are not views by themselves. The views tree only holds views. This means that this code cannot work: Dim B4XFloatTextField1 As B4XFloatTextField = CLV.GetPanel(x).GetView(y) The actual view that is added to the views tree...

www.b4x.com

 

[Filippo]

All other CustomViews that were either updated to this new standard, or were created after 20. May 2020 this became standard. And the xCLV is not one of them.

[B4X] How to get <custom view here> from <CLV or any other container>

This is a common question and for a good reason. Custom views classes are not views by themselves. The views tree only holds views. This means that this code cannot work: Dim B4XFloatTextField1 As B4XFloatTextField = CLV.GetPanel(x).GetView(y) The actual view that is added to the views tree...

www.b4x.com

I can live with this without problems, but what's wrong with standardizing the xCustomListview? Is there a technical problem I don't know about?

I myself try to standardize all my own customviews, I think this is normal.

 

[Erel]

The reason that the discussed standard wasn't implemented in xCLV is that it isn't a backward compatible change. Apps might rely on the Tag property being Null or empty.