void (@NotNull ComboBoxEditor cbe) { Component ec = cbe.getEditorComponent(); if (ec != null) { editorKeyListener = new KeyAdapter() { @Override public void keyPressed(KeyEvent e) { process(e); } @Override public void keyReleased(KeyEvent e) { process(e); } private void process(KeyEvent e) { final int code = e.getKeyCode(); if ((code == KeyEvent.VK_UP || code == KeyEvent.VK_DOWN) && e.getModifiers() == 0) { comboBox.dispatchEvent(e); } } }; ec.addKeyListener(editorKeyListener); } }