Question

我编写了这个程序，它有一个JComboBox，其中的项目代表我的数据库中的表，每个项目都应该显示它的内容，因为它们在选择时在JTable的数据库中。我运行程序，但是当我选择组合框项目时，只有comboBox中的第一项显示其在JTable上的内容，后续选择不显示任何内容。有人可以看看它并告诉我我做得对吗？或者建议任何有用的教程？我将非常感谢您的帮助，提前谢谢！

public class InventoryItems extends javax.swing.JFrame {
/**
 * 
 */
private static final long serialVersionUID = 1L;
private Object[] comboItems = new phoneClass().phoneManufacturerArray();
private JComboBox phoneBrandCombo = new JComboBox(comboItems);
private JPanel brandPane;
private JPanel instructionPane;
private JLabel instruction, brandLabel;
private JScrollPane scrollPane;
private JTable table;
private Object sel;
private Connection con;
private Statement stm;
private ResultSet rset;
private ResultSetMetaData meta;

/**
* Auto-generated main method to display this JFrame
*/
public static void main(String[] args) {
    SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            /**
             * Add a Look&F to the GUI
             */
            try{
                UIManager.setLookAndFeel("com.jtattoo.plaf.aluminium.AluminiumLookAndFeel");
             } catch (ClassNotFoundException ex) {
                  java.util.logging.Logger.getLogger(LoginInterface.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
              } catch (InstantiationException ex) {
                  java.util.logging.Logger.getLogger(LoginInterface.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
              } catch (IllegalAccessException ex) {
                  java.util.logging.Logger.getLogger(LoginInterface.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
              } catch (javax.swing.UnsupportedLookAndFeelException ex) {
                  java.util.logging.Logger.getLogger(LoginInterface.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
              }
            InventoryItems inst = new InventoryItems();
            inst.setLocationRelativeTo(null);
            inst.setVisible(true);
        }
    });
}

public InventoryItems() {
    super();
    initGUI();
}

private void initGUI() {
    try {
        setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
        /**
         * rows and column names declared as vectors.
         */
         final Vector columnNames = new Vector();
         final Vector data = new Vector();
          sel = phoneBrandCombo.getSelectedItem();

           //Get Selected Items and retrieve contents based on selected Item.

           try{
               try{
                  Class.forName("com.mysql.jdbc.Driver").newInstance();
                 }catch(ClassNotFoundException cnf){
                  System.out.println("Class Not Found Exception: "+cnf);
                 }catch(IllegalAccessException iaE){
                  System.out.println("Illegal Access Exception: "+iaE);
                 }catch(InstantiationException iE){
                  System.out.println("Instantiation Exception: "+iE);
                }
                 con = DriverManager.getConnection("jdbc:mysql://localhost:3306/"
                    + "phoneshopsystem", dbLogin.dbUser(), dbLogin.dbPwd());
                 String query = "SELECT phoneID, phoneModel, phonePrice, QuantityInStock FROM "+sel;
                  stm = con.createStatement();
                   rset = stm.executeQuery(query);
                 meta = rset.getMetaData();

                int columns = meta.getColumnCount();

                //Get Column Names

                 for (int i = 1; i <= columns; i++)
                    {
                        columnNames.addElement( meta.getColumnName(i) );
                    }

                 while (rset.next())
                    {

                        Vector row = new Vector(columns);

                          for (int i = 1; i <= columns; i++)
                          {
                            row.addElement( rset.getObject(i) );
                          }

                          //Fill JTable rows with database table rows

                        data.addElement( row );
                    }
                rset.close();
                stm.close();
                con.close();

            }catch(SQLException sql){
                JOptionPane.showMessageDialog(null, "Table SQL Exception@: "+sql.getMessage());
            }

          /**
           * Initialise the Table with the rows and column names
           * retrieved from the database resultSet.
           */

table = new JTable(data, columnNames){
    private static final long serialVersionUID = 1L;

        public Class getColumnClass(int column){
            for(int row = 0; row < getRowCount(); row++){
                Object o = getValueAt(row, column);

                 if(o != null){
                     return o.getClass();
                 }
            }
            return Object.class;
        }
    };

    /**
    * Table properties
    */
{
//table.setPreferredSize(new java.awt.Dimension(534, 180));
table.setAutoResizeMode(JTable.AUTO_RESIZE_ALL_COLUMNS);
table.setGridColor(Color.LIGHT_GRAY);
table.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
table.setSelectionBackground(new Color(248, 248, 248));
table.setSelectionForeground(new Color(51, 0, 51));
table.setBackground(new java.awt.Color(248,248,248));
}
    // Add Table to JScrollPane
{
scrollPane = new JScrollPane();
scrollPane.setPreferredSize(new java.awt.Dimension(534, 189));
scrollPane.setBackground(new java.awt.Color(212,208,200));
scrollPane.setBorder(BorderFactory.createTitledBorder(""));
scrollPane.setViewportView(table);
getContentPane().add(scrollPane, BorderLayout.SOUTH);
}

{
instructionPane = new JPanel();
FlowLayout instructionPaneLayout = new FlowLayout();
instructionPane.setLayout(instructionPaneLayout);
instruction = new JLabel();
instruction.setText("<html><body><br><p>"
            + "Select The Phone-Brand e.g 'Nokia',"
            + " To View Inventory."
            + "</p><br></body></html>");
instruction.setFont(new Font("Times New Roman", 3, 11));
instruction.setHorizontalAlignment(JLabel.CENTER);
instruction.setVerticalAlignment(JLabel.CENTER);
instruction.setBackground(new Color(240, 240, 240));
instruction.setEnabled(false);
instructionPane.add(instruction);
getContentPane().add(instruction, BorderLayout.NORTH);
}

{
brandPane = new JPanel();
FlowLayout brandPaneLayout = new FlowLayout();
brandPane.setLayout(brandPaneLayout);
brandLabel = new JLabel("Phone Brands: ");
brandLabel.setEnabled(false);
brandPane.add(brandLabel);
phoneBrandCombo.addActionListener(new ActionListener(){
    @Override
        public void actionPerformed(ActionEvent ae){
            if(ae.getSource() == phoneBrandCombo.getSelectedItem()){
                phoneBrandCombo.getSelectedItem();
            }
    }
});
brandPane.add(phoneBrandCombo);
brandPane.setBackground(new java.awt.Color(240,240,240));
getContentPane().add(brandPane, BorderLayout.CENTER);
}

pack();
setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
getContentPane().setBackground(new java.awt.Color(240,240,240));
setPreferredSize(new Dimension(550, 330));

Answer 1

您只需在构建该数据时将数据加载到Jtable，然后您就永远不会这样做，因为Jtable在您选择JComboBox中的其他项目时不会更新

而不是在ActionListener使用phoneBrandCombo上使用ItemListener，而不是下一个：{/ p>

 phoneBrandCombo.addItemListener(new ItemListener() {

        @Override
        public void itemStateChanged(ItemEvent arg0) {
            if(arg0.getStateChange() == ItemEvent.SELECTED){
                Object object = ((JComboBox)arg0.getSource()).getSelectedItem();
                //loadDataFromDBToTable(object);
            }
        }
    });

此处loadDataFromDBToTable(object);是一种向选定JTable的{{1}}加载新数据的方法。

了解使用JTable和JComboBox。

Answer 2

它可以正常使用：

phoneBrandCombo.addItemListener(new ItemListener(){
@Override
    public void itemStateChanged(ItemEvent ie){
        if(ie.getStateChange() == ItemEvent.SELECTED){
            selectedItem = ((JComboBox)ie.getSource()).getSelectedItem(); 
classes.loadTableData db = new classes.loadTableData();
db.loadData(selectedItem, data, columnNames);

table.setModel(new DefaultTableModel(data, columnNames));
  }else{
         data.removeAllElements();
         columNames.removeAllElements();
  }

} }）;

将JComboBox绑定到JTable

2 个答案: