jComboBox級聯

//事件

 private void jComboBox_room1ItemStateChanged(java.awt.event.ItemEvent evt) {                                                
        //得到jComboBox_room2列表

//如果列表下第一行爲空，加上此行，否則容易有異常
        JComboBox jc = new JComboBox();
        if (evt.getStateChange() == ItemEvent.SELECTED) {
            if (jc != null) {
                jComboBox_room2.removeAllItems();
                jComboBox_room2.addItem("");

//獲得下級列表
                m_getGas_room2_list();
            }
        }
    }