Example Depot

// Create a read-only combobox String[] items = {"Ant", "Ape", "Bat", "Boa", "Cat"}; JComboBox cb = new JComboBox(items); // Create and register the key listener cb.addKeyListener(new MyKeyListener()); // This key listener displays the menu only if the pressed key // does not select a new item or if the selected item is not unique. class MyKeyListener extends KeyAdapter { public void keyPressed(KeyEvent evt) { JComboBox cb = (JComboBox)evt.getSource(); // At this point, the selection in the combobox has already been // changed; get the index of the new selection int curIx = cb.getSelectedIndex(); // Get pressed character char ch = evt.getKeyChar(); // Get installed key selection manager JComboBox.KeySelectionManager ksm = cb.getKeySelectionManager(); if (ksm != null) { // Determine if another item has the same prefix int ix = ksm.selectionForKey(ch, cb.getModel()); boolean noMatch = ix < 0; boolean uniqueItem = ix == curIx; // Display menu if no matching items or the if the selection is not unique if (noMatch || !uniqueItem) { cb.showPopup(); } } } }