如何在其他位置设置JDropDown子菜单

Question

我创建了一个JDropDown菜单。我需要在JFrame上其他位置的子菜单，基本上，这是另一个JDropDown菜单。并以类似“否”下拉菜单的条件显示在开始处，但在单击任何下拉选项后，将显示另一个下拉菜单，以及基于主下拉菜单的第二个下拉菜单的选项。

我已经尝试过该代码。单击第一个下拉菜单中的任何选项，就会显示第二个下拉菜单。但是如果我再用cb.setSelectedIndex（1）添加一件事，那将无法工作。

String[] choices = {"Redeem","Prepaid", "FRC","Offices","Individual Bags","Gift Subscription","E-Gift Card","My Account","Wp-Admin","Shipstaion","Any date changes"}; 
final JComboBox cb = new JComboBox(choices); cb.setBounds(134,200, 170,30); 
cb.setSelectedIndex(0);
cb.addActionListener(new ActionListener(){ 
     public void actionPerformed(ActionEvent e){ 
         try { 
            String[ ] choices1 = {"Redeem Remaining & Redeem Gift Card","Redeem of Tasting Kit Sub","US & NON-US Redeem","Manually Created Vouchers"}; 
            final JComboBox cb1 = new JComboBox(choices1);
            cb1.setBounds(100,250, 250,30); 
            JF.add(cb1); 
         } catch (Exception e1) { e1.printStackTrace(); } 
     } 
});

预期结果应该是基于主下拉选项显示的第二个下拉选项。