java.lang.IllegalStateException while using Document Listener in TextArea, Java
Solution 1
You cannot modify the document inside the DocumentListener. Write a custom Document instead, which overrides the insertString() or remove() methods.
From Java Tutorials: How to write a DocumentListener
Document listeners should not modify the contents of the document; The change is already complete by the time the listener is notified of the change. Instead, write a custom document that overrides the insertString or remove methods, or both. See Listening for Changes on a Document for details.
Solution 2
If you want to mutate in the listener you can launch a separate thread to do it later with SwingUtilities.invokeLater. Be careful because the modifications from the separate thread will call the listener again, so set a boolean before launching the thread, return immediately from the listener if it is set and reset it after the modifications have been done in the separate thread.
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Updated on July 19, 2022Comments
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Sunil Kumar Sahoo almost 2 years
DocumentListener dl = new MessageDocumentListener(); ((AbstractDocument) nboxArea.getDocument()).setDocumentFilter(new DocumentFilter() { public void insertString(FilterBypass fb, int offset, String string, AttributeSet attr) throws BadLocationException { string = string.replaceAll("\t", ""); super.insertString(fb, offset, string,(javax.swing.text.AttributeSet) attr); } public void replace(FilterBypass fb, int offset, int length, String text, AttributeSet attrs) throws BadLocationException { text = text.replaceAll("\t", ""); //TODO must do something here super.replace(fb, offset, length, text,(javax.swing.text.AttributeSet) attrs); } }); JTextArea evArea = (JTextArea) c; evArea.getDocument().removeDocumentListener(dl); evArea.setText(originalMessage);
In this case I found the following error during set text in textarea. I do not know how to resolve.
Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException: Attempt to mutate in notification
I think the problem is to set text in document or setting document in document listener. But I do not know how to solve this. Please help me to solve this issue.