Question

I’m developing an autocompletion functionality (that consists in a little window under the caret position that suggest what you’ll writing) extending a JTextPane, and in a KeyAdapter associated to this component I wrote this:

...
@Override
public void keyReleased(KeyEvent e) {
    if (Character.isLetterOrDigit(e.getKeyChar())) {
        p = getCaret().getMagicCaretPosition();
        if (p != null) {
            SwingUtilities.convertPointToScreen(p, this);
            p.x = p.x + 2;
            p.y = p.y + 20;
            autocompletion.setLocation(p.x, p.y);
        }
    }
}
...

The problem is that sometime getCaret().getMagicCaretPosition() returns null, and I can’t understand why.

What is the legal way to invoke this method, or to implement this functionality?

Answer 1

1) I hope that (little window ) == JWindow don’t forget declare JWindow(Window owner)

2) then you can two choices use

• JTable with one Column, there so simple to implements RowFilter, no required solving anything that you describe, only implemented filtering from simple JTextField

• JList with AutoComplete JComboBox / JTextField

3) KeyListener isn’t correct listener look at Document/DocumentListener

4) easiest and most confortable way is implement a JTable, and with hightlighting