ParagraphView and disappearing caret

Question

Hi!
I am currently working on a EditorKit to make a custom editor. I extended AbstractDocument and created a custom Element structure that is not based on the abstract elements provided by AbstractDocument. Currently I have three type of elements: Chapter, Paragraph and Text. The Chapter is the root of the element structure and there is only one Chapter element in a document. The chapter contains Paragraphs, and Paragraphs contain text elements. Text elements except the last ones in a Paragraph do not contain endlines. So basically a Paragraph is a line of text with different styled chunks that are stored in the Text elements.
My viewfactory basically does this:
          if (elem instanceof TextElement) {
               return new LabelView(elem);
          if (elem instanceof ParagraphElement) {
               return new ParagraphView(elem);
          if (elem instanceof ChapterElement) {
               return new BoxView(elem, View.Y_AXIS);
The problem is that when I want to move around with my caret it disappears when I reach the end of the line instead of appearing at the beginning of the next line. On top of that, it throws the following exception:
Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: -1
     at javax.swing.text.CompositeView.getView(CompositeView.java:143)
     at javax.swing.text.Utilities.getNextVisualPositionFrom(Utilities.java:985)
     at javax.swing.text.CompositeView.getNextEastWestVisualPositionFrom(CompositeView.java:732)
     at javax.swing.text.CompositeView.getNextVisualPositionFrom(CompositeView.java:454)
     at javax.swing.text.Utilities.getNextVisualPositionFrom(Utilities.java:987)
     at javax.swing.text.CompositeView.getNextEastWestVisualPositionFrom(CompositeView.java:732)
     at javax.swing.text.CompositeView.getNextVisualPositionFrom(CompositeView.java:454)
     at javax.swing.plaf.basic.BasicTextUI$RootView.getNextVisualPositionFrom(BasicTextUI.java:1568)
     at javax.swing.plaf.basic.BasicTextUI.getNextVisualPositionFrom(BasicTextUI.java:1115)
     at javax.swing.text.DefaultEditorKit$NextVisualPositionAction.actionPerformed(DefaultEditorKit.java:1666)
     at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1636)
     at javax.swing.JComponent.processKeyBinding(JComponent.java:2849)
     at javax.swing.JComponent.processKeyBindings(JComponent.java:2884)
     at javax.swing.JComponent.processKeyEvent(JComponent.java:2812)
     at java.awt.Component.processEvent(Component.java:5911)
     at java.awt.Container.processEvent(Container.java:2023)
     at java.awt.Component.dispatchEventImpl(Component.java:4501)
     at java.awt.Container.dispatchEventImpl(Container.java:2081)
     at java.awt.Component.dispatchEvent(Component.java:4331)
     at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1848)
     at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:704)
     at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:969)
     at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:841)
     at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:668)
     at java.awt.Component.dispatchEventImpl(Component.java:4373)
     at java.awt.Container.dispatchEventImpl(Container.java:2081)
     at java.awt.Window.dispatchEventImpl(Window.java:2458)
     at java.awt.Component.dispatchEvent(Component.java:4331)
     at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
     at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
     at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
     at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
Originally I had Paragraphs as the leaf elements containing the text (no Text elements), and I used the ParagraphView without LabelViews. The exact same was the problem.
Do you have an idea what goes wrong?

Answer 1

I didn't extend SUN classes because I expected them to work "out of the box". I use javax.swing.text.ParagraphView directly. It is not abstract so I expected it to work without overriding anything. In my ViewFactory I simply instantiate it:
if (elem instanceof TextElement) {
  return new LabelView(elem);
if (elem instanceof ParagraphElement) {
  return new ParagraphView(elem);
if (elem instanceof ChapterElement) {
  return new BoxView(elem, View.Y_AXIS);
}I do not have custom View classes, I use the ones that are provided in the package javax.swing.text. I only have a custom Document class derived from AbstractDocument, and custom Elements that are directly implementing the Element interface.
I am trying to achieve to have a custom document model that is a bit more structured than DefaultStyledDocument.
Currently my document model is very simple. It has a single chapter element as root which has paragraphs and the paragraphs contain text chunks (so text inside paragraphs could have different styles and semantics).
Is ParagraphView expecting a specific Document model and will not work with other Document models? If so, then how could I display the paragraphs of my document model (ParagraphElements) so they look like paragraphs (line wrapping, indents etc.)?