Trying to amend textArea

Question

I have a textArea(attached is a document listenter and a CaretListener) where I am trying to amend the contents. What I am trying to accomplish is when a user inputs text into the textArea that he/she cannot enter text past a certain point (ie caret postion 200). Also, if the text that gets inserted causes the text to go longer than caret position 200, then the text gets cut off.
The problem is I get the following error when I try and replace or set the textArea.
(java.lang.IllegalStateException: Attempt to mutate in notification)
Yet I have another program where the same thing works fine in an actionListener. I do not understand why I can not get it to work in the document listener. The textArea gets locked for some reason and I can not ammend it. I f someone can help me that would be nice of you.
java.lang.IllegalStateException: Attempt to mutate in notification
public void setCursor()
if(textArea.getCaretPosition() >= 200)
textArea.setCaretPosition(200);
public void delText()
if(textArea.getText().length() > 200)
String area = textArea.getText().substring(0, 199);
textArea.setText(" ");
textArea.replaceRange(area, 0 , 199); /* java.lang.IllegalStateException: Attempt to mutate in
notification */
class TextDocListener implements DocumentListener
public void insertUpdate(DocumentEvent e) {delText();}
public void removeUpdate(DocumentEvent e) {}
public void changedUpdate(DocumentEvent e) {}
class TextCaretListener implements CaretListener
public void caretUpdate(CaretEvent e) { setCursor(); }

Answer 1

Hi!
Subclass javax.swing.text.PlainDocument
then:
public void insertString(int offset, String newString, javax.swing.text.AttributeSet set) throws javax.swing.text.BadLocationException
           String s = this.getContent()+newString;
           if(s.length()<200)
                   super.insertString(offset, newString, set);
            else
               int cap = 200-this.getContent().length();
               if(cap>0)
                      String ins = newString.subString(0, cap);
                      super.insertString(offset, ins, set);
}Finally, when creating the TextArea call:
myTextArea.setDocument(myPlainDocument);:)