Question

我有两张MySQL表格，如下图所示

电影

MOVIE_TITLE

         JComboBox combo = new JComboBox();
        combo.setBounds(125, 15, 190, 20);
         try {   
            DatabaseConnection db=new DatabaseConnection();
            Connection connect=db.getConnection();
            String sql="Select title FROM movie_title";
            PreparedStatement ps=connect.prepareStatement(sql);
            ResultSet rs = ps.executeQuery();
            while (rs.next()) {
            String name = rs.getString("title");
            combo.addItem(name);            
        }

    } catch (Exception e) {
        System.out.println("null");
    }
         combo.addActionListener(new ActionListener()
        {
    public void actionPerformed(ActionEvent event)
    {
        JComboBox comboBox=(JComboBox) event.getSource();
         Object selected = comboBox.getSelectedItem();
         displayDay(selected);
    }

    private void displayDay(Object selected) {
        // TODO Auto-generated method stub
         try {  
                combo1.removeAllItems();
                DatabaseConnection db=new DatabaseConnection();
                Connection connect=db.getConnection();
                String sql="Select movie_day FROM movie WHERE movie_title = ?";
                PreparedStatement ps=connect.prepareStatement(sql);
                ps.setObject(1, selected);
                ResultSet rs = ps.executeQuery();
                while (rs.next()) {
                String day = rs.getString("movie_day");
                combo1.addItem(day);   
            }

        } catch (Exception e) {
            System.out.println("null");
        }

    }
        });

我在ActionListener中实施了comboBox。当用户选择电影Marvel的美国队长时，它将从电影中获取movie_day项并加载到combo1中。 有没有办法让combo1只显示2016年4月28日星期日的movie_day而不是两次？

修改

private void displayDay(Object selected) {
        // TODO Auto-generated method stub
         try {  
                combo1.removeAllItems();
                DatabaseConnection db=new DatabaseConnection();
                Connection connect=db.getConnection();
                String sql="Select movie_day FROM movie WHERE movie_title = ?";
                PreparedStatement ps=connect.prepareStatement(sql);
                ps.setObject(1, selected);
                ResultSet rs = ps.executeQuery();
                while (rs.next()) {
                String day = rs.getString("movie_day");
                DefaultComboBoxModel model = (DefaultComboBoxModel)combo1.getModel();                
                if (model.getIndexOf(day) == -1)
                {
                    combo1.addItem(day);
                }

            }

        } catch (Exception e) {
            System.out.println("null");
        }

Answer 1

有没有办法可以让combo1只显示2016年4月28日星期日的movie_day而不是两次？

在将日期添加到组合框之前，您需要检查日期是否已存在。

DefaultComboBoxModel model = (DefaultComboBoxModel)comboBox.getModel();

if (model.getIndexOf(theDate) == -1)
{
    comboBox.addItem( theDate );
}

您还可以将SQL语句更改为仅获取＆＃34; unique＆＃34;日期，但我不太了解SQL，以便为您提供实际的语法。也许这个SQL Tutorial会有所帮助，否则你需要找到一个更好的教程。

将数据从MySQL加载到JComboBox

1 个答案: