Question

我使用Swing GUI为计算机商店设计了一个库存/销售信息系统（虚构）。其中一个功能是显示某些产品在一年内销售情况的基本条形图。

从名为dbsales的MySQL数据库调用数据，并使用jComboBox（cboAnSales）选择产品类别。
我有一个方法（public void graph()），它具有生成图形的编码。

项目的数据显示在文本字段中，图表使用该信息进行显示。在每个类别的cboAnSales if语句内调用该方法。

现在的问题是它在自己的图表上生成每个项目。例如，“电缆”类别中有7个项目，当我选择它时，它会生成7个图形（每个项目一个）我需要在一张图表上显示所有7个项目。

我怎样才能做到这一点？

这是cboAnSales的电缆部分：

private void cboAnSalesActionPerformed(java.awt.event.ActionEvent evt) {                                           
    if (cboAnSales.getSelectedIndex() == 1)
    { 
        try
        {
            String sql = "select * from dbsales where category ='" + "Cable" + "'";
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = (Connection)
            DriverManager.getConnection("jdbc:mysql://localhost:3306/salventri","root","password");
            Statement stmt=con.createStatement();
            ResultSet rs = stmt.executeQuery(sql); 
            DefaultListModel model = new DefaultListModel();
            while(rs.next())
            {
                String ID = rs.getString("pid");
                txtpid.setText(ID);
                String brand = rs.getString("pbrand");
                txtBrand.setText(brand);
                String name = rs.getString("pname");
                txtName.setText(name);
                String category = rs.getString("category");
                txtCategory.setText(category);
                String unitSold = rs.getString("usold");
                txtUnitsSold.setText(unitSold);
                graph();
            }       
        }
        catch (Exception e)
        {
        }
    }

以下是public void graph()方法中我的图表的编码：

String unitsSold = txtUnitsSold.getText();
String brand = txtBrand.getText();
String name = txtName.getText();
String cat = txtCategory.getText();

DefaultCategoryDataset ddataset = new DefaultCategoryDataset();
ddataset.setValue(new Double(unitsSold), cat, brand + " " + name);

JFreeChart chart = ChartFactory.createBarChart3D("Annual Sales Performance", cat, "Number of Units Sold", ddataset);
chart.getTitle().setPaint(Color.RED);
CategoryPlot p = chart.getCategoryPlot();
p.setRangeGridlinePaint(Color.BLUE);
ChartFrame frame2 = new ChartFrame("Annual Sales", chart);
frame2.setVisible(true);
frame2.setSize(450,350);

Answer 1

归功于WillShackleford，我的问题的解决方案导致了public void graph()中的以下代码：

public void graph()
    {
       String year = cboAnnYear.getSelectedItem().toString();
       if(cboAnSales.getSelectedIndex() == 1) 
       {
        try
        {
            //declaring the type of category in the column
            String text = "Cable";
            //Select statement getting the row count
         String sql = "select count(category) from dbsales where category ='" + text + "'";
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = (Connection)
            DriverManager.getConnection("jdbc:mysql://localhost:3306/salventri","root","password");
            PreparedStatement stmt = con.prepareStatement("select * from dbsales where category=?");
            stmt.setString(1, text);
            ResultSet rs = stmt.executeQuery();
            DefaultCategoryDataset ddataset = new DefaultCategoryDataset();
            while (rs.next()) 
            {
                ddataset.setValue(new Double(rs.getDouble("usold")),
            rs.getString("pbrand") + " " + rs.getString("pname"),
            rs.getString("syear"));
            }

             JFreeChart chart = ChartFactory.createBarChart3D("Annual Sales Performance", text, "Number of Units Sold", ddataset);
            chart.getTitle().setPaint(Color.RED);
            CategoryPlot p = chart.getCategoryPlot();
            p.setRangeGridlinePaint(Color.BLUE);
            ChartFrame frame2 = new ChartFrame("Annual Sales", chart);
            frame2.setVisible(true);
            frame2.setSize(900,700);
            }

如何在一个图表上显示多个项目？

1 个答案: