Re: java swing jtextfield modifiying input

Knute Johnson <>
Mon, 04 Dec 2006 08:54:09 -0800
brf wrote:

To make simple autocorrections in an JTextField, receiving textinput, I
tried to change the text after caretlistener events. But I only get

pf, touched: - 0 - 0
Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException:
to mutate in notification

main creates a frame with
        JFrame f = new JFrame ("Test");
        Container inhalt = f.getContentPane();

         PhraseField pf = new PhraseField (30);
         inhalt.add (pf [i]);
         pf.addActionListener (new TxtFldAct ());
         pf.addCaretListener (new TxtFldCar ());
         f.setDefaultCloseOperation (JFrame.DISPOSE_ON_CLOSE);

and the Listeners try to modify the textField

public class TxtFldCar implements CaretListener
    public void caretUpdate (CaretEvent e)
        PhraseField tf = (PhraseField) e.getSource();
        tf.touched ();

via the used subclass of JTextField

public class PhraseField extends JTextField
    public PhraseField (int columns) { this ("", columns); }
    public PhraseField (String text, int columns)
        super (text, columns);
        this.constant = true;
        this.value = "";
    public void touched ()
        this.setText ("some corrected String"); }

Is this the right solution and if so what is my error?

Probably not.

If this is not a good solution, what is a besser one?

Yes. Look at the interface javax.swing.text.Document. You can do some
amazing things with the Document.


Knute Johnson
email s/nospam/knute/

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