动态将项目添加到JComboBox

如何使用ComboBoxModel？像这样…

    Jframe frame = new Jframe("Combo Box Demo");    frame.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE);    frame.setSize(200, 200);    frame.setLayout(new FlowLayout());    Vector comboBoxItems=new Vector();    comboBoxItems.add("A");    comboBoxItems.add("B");    comboBoxItems.add("C");    comboBoxItems.add("D");    comboBoxItems.add("E");    final DefaultComboBoxModel model = new DefaultComboBoxModel(comboBoxItems);    JComboBox comboBox = new JComboBox(model);    frame.add(comboBox);    JButton button = new JButton("Add new element in combo box");    frame.add(button);    button.addActionListener(new ActionListener() {        @Override        public void actionPerformed(ActionEvent ae) { model.addElement("F");        }    });    frame.setVisible(true);