Android Question Using ScrollView in B4A and B4J (B4XPages project)

asales · Feb 19, 2023

I'm trying to create a cross platform project.
I have a layout with a long panel that I load in another layout into a scrollview.

This is the code:

B4X:

Private pnlProfile As B4XView
Private scroll1 As B4XView

Private Sub B4XPage_Created (Root1 As B4XView)
    Root.LoadLayout("layScroll")
    scroll1.GetView(0).LoadLayout("profile")
    scroll1.ScrollViewContentHeight = pnlProfile.Height
End Sub

It works when I compile in B4A, but in B4J I get this error:

B4X:

java.lang.RuntimeException: java.lang.ClassCastException: class javafx.scene.control.ScrollPane cannot be cast to class javafx.scene.layout.Pane (javafx.scene.control.ScrollPane is in module javafx.controls of loader 'app'; javafx.scene.layout.Pane is in module javafx.graphics of loader 'app')

How can I fix it?

Thanks in advance for any tips.

PaulMeuris · Feb 19, 2023

You can also use a CustomListView...
In B4J a Scrollpane has an innernode that is used to add views to...

Erel · Feb 19, 2023

B4X:

 scroll1.ScrollViewInnerPanel.GetView(0)

asales · Feb 19, 2023

Erel said:
B4X:

scroll1.ScrollViewInnerPanel.GetView(0)

I try this:

B4X:

Root.LoadLayout("layScroll")
scroll1.ScrollViewInnerPanel.GetView(0).LoadLayout("profile")

but now I get this errors:

B4X:

B4J:
java.lang.RuntimeException: java.lang.RuntimeException: Object should first be initialized (B4XView).

B4A:
java.lang.RuntimeException: Object should first be initialized (View).

Erel · Feb 20, 2023

Sorry it should be:

B4X:

scroll1.ScrollViewInnerPanel.LoadLayout("profile")

asales · Feb 20, 2023

Erel said:
Sorry it should be:

B4X:

scroll1.ScrollViewInnerPanel.LoadLayout("profile")

Thanks, but still works only in B4A.

Here my B4X Project (B4A and B4J).
In B4J the error remains:

B4X:

java.lang.RuntimeException: java.lang.RuntimeException: Object should first be initialized (B4XView).

PaulMeuris · Feb 21, 2023

I did some testing with this code:

B4X:

If scroll1.IsInitialized = True Then Log("scroll1 is initialized")

scroll1 is initialized

But the scroll1 B4XView still gave the same error.
So here is the code with a ScrollPane (B4J):

using B4J ScrollPane:

    'Private scroll1 As B4XView   
    Private scroll1 As ScrollPane

    'If scroll1.IsInitialized = True Then Log("scroll1 is initialized")
    'scroll1.ScrollViewInnerPanel.LoadLayout("myprofile")   
    'scroll1.ScrollViewContentHeight = pnlData.Height
    scroll1.LoadLayout("myprofile",scroll1.PrefWidth,scroll1.prefHeight)
    scroll1.InnerNode.PrefHeight = pnlData.Height

This is the result:

In the Visual Designer i have stretched the scroll1 ScrollPane to cover the form width and height. The anchors remained.
The comments in the code were the original lines with a B4XView.
The question still remains why the B4XView throws this error... can somebody explain this?

Erel · Feb 21, 2023

You are both right.

The layout must be loaded like this:

B4X:

scroll1.As(ScrollPane).LoadLayout("myprofile", 320dip, 1070dip)

From there on you can access ScrollViewInnerPanel.

Note that there is nothing bad with keeping it as a ScrollPane instead of B4XView.

Android Question Using ScrollView in B4A and B4J (B4XPages project)

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