private void initActions() {
    InputMap inputMap = getInputMap(WHEN_FOCUSED);
    inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0, false), "moveFocusDown");
    inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0, false), "moveFocusUp");
    inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0, false), "collapse");
    inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0, false), "expand");

    ActionMap actionMap = getActionMap();
    actionMap.put("moveFocusDown", new MoveFocusAction(true));
    actionMap.put("moveFocusUp", new MoveFocusAction(false));
    actionMap.put("collapse", new ExpandAction(false));
    actionMap.put("expand", new ExpandAction(true));
  }
private void initActions()