如何在JFrame刷新数据库查询？

Question

good day!

I am having a problem on showing the updated version of my database to a JTable frame...

Everything inside my JFrame were just Generated, I just follow the instruction in this link: Binding JTable with MySQL

It works properly until, I added a new JFrame for the UPDATES of the Database, when I hit the button VIEW INVENTORY (JFrame that consist the JTable showing the data at MySQL), it doesn't show the updated version of the database.

But, after closing the Application and run the ViewInventory JFrame.. it was already Updated.

Please Help... this is the generated Code:

public class ViewInventory extends javax.swing.JFrame {

    public ViewInventory() {
        initComponents();
        setLocation(300, 120);
    }
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {
        bindingGroup = new org.jdesktop.beansbinding.BindingGroup();

        inventoryPUEntityManager = java.beans.Beans.isDesignTime() ? null : javax.persistence.Persistence.createEntityManagerFactory("inventoryPU").createEntityManager();
        itemsQuery = java.beans.Beans.isDesignTime() ? null : inventoryPUEntityManager.createQuery("SELECT i FROM Items i");
        itemsList = java.beans.Beans.isDesignTime() ? java.util.Collections.emptyList() : itemsQuery.getResultList();
        jScrollPane1 = new javax.swing.JScrollPane();
        jTable1 = new javax.swing.JTable();
        jLabel1 = new javax.swing.JLabel();
        jButton1 = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jTable1.setAutoCreateRowSorter(true);
        jTable1.setAlignmentX(1.0F);
        jTable1.setAlignmentY(2.0F);
        jTable1.setAutoResizeMode(javax.swing.JTable.AUTO_RESIZE_ALL_COLUMNS);
        jTable1.setSelectionMode(javax.swing.ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);

        org.jdesktop.swingbinding.JTableBinding jTableBinding = org.jdesktop.swingbinding.SwingBindings.createJTableBinding(org.jdesktop.beansbinding.AutoBinding.UpdateStrategy.READ_WRITE, itemsList, jTable1);
        org.jdesktop.swingbinding.JTableBinding.ColumnBinding columnBinding = jTableBinding.addColumnBinding(org.jdesktop.beansbinding.ELProperty.create("${id}"));
        columnBinding.setColumnName("Id");
        columnBinding.setColumnClass(Integer.class);
        columnBinding = jTableBinding.addColumnBinding(org.jdesktop.beansbinding.ELProperty.create("${itemName}"));
        columnBinding.setColumnName("Item Name");
        columnBinding.setColumnClass(String.class);
        columnBinding = jTableBinding.addColumnBinding(org.jdesktop.beansbinding.ELProperty.create("${category}"));
        columnBinding.setColumnName("Category");
        columnBinding.setColumnClass(String.class);
        columnBinding = jTableBinding.addColumnBinding(org.jdesktop.beansbinding.ELProperty.create("${QBox}"));
        columnBinding.setColumnName("QBox");
        columnBinding.setColumnClass(Integer.class);
        columnBinding = jTableBinding.addColumnBinding(org.jdesktop.beansbinding.ELProperty.create("${unitPriceBox}"));
        columnBinding.setColumnName("Unit Price Box");
        columnBinding.setColumnClass(Double.class);
        columnBinding = jTableBinding.addColumnBinding(org.jdesktop.beansbinding.ELProperty.create("${subTotalBox}"));
        columnBinding.setColumnName("Sub Total Box");
        columnBinding.setColumnClass(Double.class);
        columnBinding = jTableBinding.addColumnBinding(org.jdesktop.beansbinding.ELProperty.create("${QPc}"));
        columnBinding.setColumnName("QPc");
        columnBinding.setColumnClass(Integer.class);
        columnBinding = jTableBinding.addColumnBinding(org.jdesktop.beansbinding.ELProperty.create("${unitPricePc}"));
        columnBinding.setColumnName("Unit Price Pc");
        columnBinding.setColumnClass(Double.class);
        columnBinding = jTableBinding.addColumnBinding(org.jdesktop.beansbinding.ELProperty.create("${subTotalPc}"));
        columnBinding.setColumnName("Sub Total Pc");
        columnBinding.setColumnClass(Double.class);
        columnBinding = jTableBinding.addColumnBinding(org.jdesktop.beansbinding.ELProperty.create("${grandTotal}"));
        columnBinding.setColumnName("Grand Total");
        columnBinding.setColumnClass(Double.class);
        bindingGroup.addBinding(jTableBinding);

        jScrollPane1.setViewportView(jTable1);

        jButton1.setText("Main Menu");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 514, Short.MAX_VALUE)
                    .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 329, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(jButton1, javax.swing.GroupLayout.Alignment.TRAILING))
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 275, Short.MAX_VALUE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 14, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(14, 14, 14)
                .addComponent(jButton1)
                .addContainerGap())
        );

        bindingGroup.bind();

        pack();
    }// </editor-fold>                        

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        new Menu().setVisible(true);
        setVisible(false);
    }                                        

    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {
                new ViewInventory().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify                     
    private javax.persistence.EntityManager inventoryPUEntityManager;
    private java.util.List<inventory.Items> itemsList;
    private javax.persistence.Query itemsQuery;
    private javax.swing.JButton jButton1;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTable jTable1;
    private org.jdesktop.beansbinding.BindingGroup bindingGroup;
    // End of variables declaration                   
}

I am sorry if I displayed everything at the generated code.

and here's my EditItemDetails code:

try {
            Class.forName(Connect.DRIVER);
            Connection con = DriverManager.getConnection(Connect.CONNECTION_STRING,
                    Connect.USERNAME, Connect.PASSWORD);

            Statement stat = con.createStatement();

            ResultSet rs = stat.executeQuery("SELECT id, category,"
                    + "q_box, unit_price_box, sub_total_box, q_pc, "
                    + "unit_price_pc, sub_total_pc, grand_total from items WHERE "
                    + "item_name = '" + item_name_combobox.getSelectedItem() + "';");

            String category;
            int q_box, q_pc;
            double unit_price_box, sub_total_box, unit_price_pc, sub_total_pc,
                    grand_total;

            if (rs.next()) {
                q_box = rs.getInt("q_box");
                category = rs.getString("category");
                unit_price_box = rs.getDouble("unit_price_box");
                sub_total_box = rs.getDouble("sub_total_box");
                q_pc = rs.getInt("q_pc");
                unit_price_pc = rs.getDouble("unit_price_pc");
                sub_total_pc = rs.getDouble("sub_total_pc");
                grand_total = rs.getDouble("grand_total");

                double new_sub_total_box = q_box * Integer.parseInt(new_unit_price_box_txtfld.getText());
                double new_sub_total_pc = q_pc * Integer.parseInt(new_unit_price_pc_txtfld.getText());
                grand_total = new_sub_total_box + new_sub_total_pc;

            stat.executeUpdate("UPDATE items SET unit_price_box = " + new_unit_price_box_txtfld.getText()
                    + ", unit_price_pc = " + new_unit_price_pc_txtfld.getText()
                    + ", sub_total_box = " + new_sub_total_box
                    + ", sub_total_pc = "+ new_sub_total_pc
                    + ", grand_total = "+ grand_total
                    + " WHERE item_name = '"
                    + item_name_combobox.getSelectedItem() + "';");

                sub_total_box_txtfld.setText(Double.toString(new_sub_total_box));
                sub_total_pc_txtfld.setText(Double.toString(new_sub_total_pc));
                grand_total_txtfld.setText(Double.toString(grand_total));

                lblmsg.setText("Record Saved!");

                con.close();
            }
        } catch (Exception e) {
            lblmsg.setText("Error: "+ e.getMessage());
            System.out.println("Error: "+ e.getMessage());
        }

Answer 1

Personally I dislike the Netbeans gui designer for a lot of reasons. It's great for prototyping and small projects, terrible for big projects and going back in and doing maintenance. But that's a rant for another time.

What's going wrong is that you're getting back a static List from the JPA query. You need to have your GUI re-run the query after your edit event to get the updated list. The way I got this kind of thing working in the gui designer was to change the collection to an ObservableList in the "Custom Creation Code":

someList = Beans.isDesignTime() ? java.util.Collections.emptyList() : ObservableCollections.observableList(new ArrayList<Something>());

Then when I had a gui event that updated the JTable contents, I do something like:

someList.clear();
someList.add(query.getResultList());

I'm doing it this way because I get the list via EJB remote session bean, and I did it a long time ago in about netbeans 6.5 or 7 (the last time I used the GUI designer to create a new form). Apparently now there is a " modifiableWrapper " and " observable " you can set on the query results. That might do what you need, otherwise do it the manual way as above.