Override the Java DefaultStyledDocument implementation

I'm a student. When I learn the GOF , I want to create the word processor mentioned in Chapter2. I choose to use Java swing, I want to extend the DefaultStyledDocument and override the insertUpdate and related methods in order to implement and manage my own Element tree, so I can practice the Composite and Flyweight Pattern. The开发者_运维百科 problem is when I override the insertUpdate method, insert newline has no effect. When inserting a newline, My Element tree will create a new Paragraph(BrachElement), but the cursor don't move to the next line, Swing just don't show it and my following characters just in the same line.

Can anyone help me, thanks.

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Try this to understand how your structure changes http://java-sl.com/JEditorPaneStructureTool.html

And this http://java-sl.com/JEditorPaneTables.html to see how to change the structures