In Java/Swing, is there a way to legally “attempt to mutate in notification”?

Question

I was wondering if there is some sort of magic I can use to get around an IllegalStateException and allow a JTextField to "attempt to mutate in notification", or in other words to set its own text if its listener is triggered.

For your information, I am trying to program an auto-complete function which returns the most likely match in a range of 12 enums in response to a user's input in the JTextField.

Here is the code sample. You'll have to pardon my clumsy algorithm which creaks out enum results. I've highlighted the code which produces the exception with a comment:

jtfElement1.addCaretListener(new CaretListener() {
            @Override
            public void caretUpdate(CaretEvent e) {                    
                String s = jtfElement1.getText();
                int[] attributes = new int[13];
                // iterate through each enum
                for (BaseEnumAttributes b: BaseEnumAttributes.values()) {
                    // iterate through the length of the current text in jtfElement1
                    for (int i = 0; i < s.length(); i++) {
                        if (s.length() <= b.toString().length()) {                                
                            if (b.toString().charAt(i) == s.charAt(i)) {
                                // increase the number of "hits" noted for that enum
                                attributes[b.ordinal()] = attributes[b.ordinal()] + 1;
                            }                                
                        }
                    }                        
                }
                int priorC = 0;
                int rightC = 0;                    
                // iterate through the "array" of enums to find the highest score
                for (int j = 0; j < attributes.length; j++) {
                    if (attributes[j] > priorC) {
                        priorC = attributes[j];
                        rightC = j;
                    }
                }                    
                if (!s.equals("")) {
                    // assign to b the Enum corresponding to the "array" with highest score
                    BaseEnumAttributes b = BaseEnumAttributes.values()[rightC];
                    iController.updateInputElement1String(b.toString());                        
                    // THIS TRIGGERS EXCEPTION 
                    jtfElement1.setText(b.toString());
                }

            }
        });

Answer 1

You are probably better off using a document filter or a custom document.

What are other listeners expected to see if the document doesn't stay the same during event dispatch?

Answer 2

Use SwingUtilities.invokeLater() placing all the modifications there

Answer 3

Maybe you can delay the setText() with a Thread to run after caretUpdate() has terminated.

Answer 4

i'm found on the same problem but i found an easy solution:

lock the caretUpdate() by a boolean if(false) while u'r setting the text to the jTextField than unlock it after . . something like this:

boolean caret = true;

private void listValueChanged(javax.swing.event.ListSelectionEvent evt) { caret = false; name.setText((String)list.getSelectedValue()); caret = true; }

private void nameCaretUpdate(javax.swing.event.CaretEvent evt) {
   if(caret){
    model = new DefaultListModel();
    this.fillList(name.getText());
    list.setModel(model);
    }
}

Answer 5

Create a custom Document and override insertString( )

filenameText = new JTextField(new FilenameDocument(), "", 0);

...

 /**
 * document which adds .xml extension if not specified
 *
 */
private class FilenameDocument extends PlainDocument {

    @Override
    public void insertString(int offset, String insertedText, AttributeSet set)
    throws BadLocationException {
        if (offset == 0) {
        insertedText = insertedText.trim( );
        }
        super.insertString(offset, insertedText, set);
        if (filenameText != null) {
            final int caretPos = filenameText.getCaretPosition();
            String text = filenameText.getText().trim();
            if (text.indexOf('.') == -1) {
                filenameText.setText(text + ".xml");
                filenameText.setCaretPosition(caretPos);
            }

        }
    }
}

Note that calling setText will result in a recursive call to insertString( ), so make sure you have a stopping condition.

Answer 6

I'm surprised no one has answered this, but would'nt you have been better off implementing an editable JSpinner with a SpinnerListModel?