如何将动作列表添加到jmenuitem

Question

1. My menuitem are being added thorugh database .
2. i have to perform action such as opening the new jframe , if a user select a particular menuitem.
3. Here the menu dimension is add to the Menubar , and under which various menuitem are being added such as Period , Entity, which are being fetch from database.

4. Now i want to open a new jframe on the click of Period menuitem .

     public void MenuExp(){ JMenu DimensionMenu = new JMenu("Dimension"); JMenu editMenu = new JMenu("Help"); jMenuBar1.add(DimensionMenu); jMenuBar1.add(editMenu); //JMenuItem newAction = new JMenuItem("Account"); //fileMenu.add(newAction); //JMenuItem newPeriod = new JMenuItem("Period"); //fileMenu.add(newPeriod); try{ Class.forName("oracle.jdbc.OracleDriver"); Connection comm = (Connection)DriverManager.getConnection("jdbc:oracle:thin:@192.168.100.25:1521:orcl","SYSTEM","Admin123"); Statement st = comm.createStatement(); String Query = "select OBJECT_NAME from RAHUL_APP1.HSP_OBJECT where OBJECT_TYPE = 2 AND OBJECT_ID <> 30" ; //and User_Name ='" + jTextField1.getText()+"'"; ResultSet rs = st.executeQuery(Query); while(rs.next()){ JMenuItem newAction = new JMenuItem(rs.getString(1)); DimensionMenu.add(newAction); rs.close(); st.close(); comm.close(); newAction.addActionListener(new ActionListener(){ public void actionPerformed(ActionEvent arg0){ System.out.println("You have clicked on the Account"); } }); } } catch(Exception e){ JOptionPane.showMessageDialog(this,e); } } 

Answer 1

You need to do some parametrization of the frame or have for example frame class stored also in DB and initialize it using reflexion...

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Update:

Implementation can be like this:

package betlista.so.swing.menuitemdialogsfromdb;

import java.awt.HeadlessException;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;

public class MainFrame extends JFrame {

    public MainFrame() {
        super("Frame");
        setDefaultCloseOperation(DISPOSE_ON_CLOSE);

        add(createMenu());

        pack();
    }

    private JMenuBar createMenu() {
        JMenuBar menuBar = new JMenuBar();

        JMenu menu = new JMenu("Open");
        menu.add(new DialogCreatingMenuItem("Dialog 1", "betlista.so.swing.menuitemdialogsfromdb.MainFrame$MyDialog1"));
        menu.add(new DialogCreatingMenuItem("Dialog 2", "betlista.so.swing.menuitemdialogsfromdb.MainFrame$MyDialog2"));

        menuBar.add(menu);

        return menuBar;
    }

    class DialogCreatingMenuItem extends JMenuItem implements ActionListener {

        String className;

        public DialogCreatingMenuItem(String text, String className) throws HeadlessException {
            super(text);
            this.className = className;
            addActionListener(this);
        }

        @Override
        public void actionPerformed(ActionEvent ae) {
            try {
                Class<JDialog> clazz = (Class<JDialog>)Class.forName(this.className);
                JDialog dialog = clazz.newInstance();
                dialog.setVisible(true);
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            } catch (InstantiationException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
        }

    }

    public static class MyDialog1 extends JDialog {
        public MyDialog1() {
            setTitle("Dialog 1");
            add(new JLabel("Dialog 1"));
            pack();
        }
    }

    public static class MyDialog2 extends JDialog {
        public MyDialog2() {
            setTitle("Dialog 2");
            add(new JLabel("Dialog 2"));
            pack();
        }       
    }

    public static void main(String[] args) {
        new MainFrame().setVisible(true);
    }

}

where Strings in

    menu.add(new DialogCreatingMenuItem("Dialog 1", "betlista.so.swing.menuitemdialogsfromdb.MainFrame$MyDialog1"));
    menu.add(new DialogCreatingMenuItem("Dialog 2", "betlista.so.swing.menuitemdialogsfromdb.MainFrame$MyDialog2"));

are retrieved from database...

Answer 2

Here is a sample code:

menuItem1.addActionListener(new ActionListener(){
                public void actionPerformed(ActionEvent e){
                    ...
                }
            });

Remember the steps to creating a menu: 1. Create a MenuBar and add to the panel 2. Create a Menu and add to MenuBar 3. Create a MenuItem and add to Menu

Then add the listener to the MenuItem

Edit: if you use it outside the try statement it should work

Answer 3

Now i want to open a new jframe on the click of Period menuitem

Of course you have to add an ActionListener to your menu to do that, but the real question is How do you determine the right listener to each menu item? Since you fetch your menu items from database then it's not that easy as it looks like.

Note: see The Use of Multiple JFrames, Good/Bad Practice?

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Option 1 (kind of dirty)

As I've said, you could store an action command and set it back to the menu item just like you set the menu's name:

while(rs.next()) { 
    String menuName =  rs.getString("menuname");
    String actionCommand = rs.getString("actioncommand");
    JMenuItem newAction = new JMenuItem(menuName);
    newAction.setActionCommand(actionCommand);
    DimensionMenu.add(newAction);
    ...
}

Then you can have a listener that make use of ActionEvent#getActionCommand() to decide the right action to perform and attach this listener to all your menu items:

class MenuActionListener implements ActionListener {

    @Override
    public void actionPerformed(ActionEvent evt) {
        String actionCommand = evt.getActionCommand();
        switch (actionCommand) {
            case "OpenNewDialog": openNewDialog(); break;
            ...
        }
    }

    private void openNewDialog() {
        // implementation here
    }
}

Then:

ActionListener listener = new MenuActionListener();

while(rs.next()) { 
    String menuName =  rs.getString("menuname");
    String actionCommand = rs.getString("actioncommand");
    JMenuItem newAction = new JMenuItem(menuName);
    newAction.setActionCommand(actionCommand);
    newAction.addActionListener(listener);
    DimensionMenu.add(newAction);
    ...
}

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Option 2

Implement Factory method pattern to create a specific ActionListener or Action based on menu's action command:

class ActionListenerFactory {

    public static Action createAction(final String actionCommand) {
        switch (actionCommand) {
            case "OpenNewDialog": return openNewDialogAction(); break;
            ...
        }
    }

    private Action openNewDialogAction() {
        Action action = new AbstractAction() {
            @Override
            public void actionPerformed(ActionEvent evt) {
                // open new dialog here
            }
        };
        return action;
    }
}

Then:

while(rs.next()) {
    String menuName =  rs.getString("menuname");
    String actionCommand = rs.getString("actioncommand");
    JMenuItem newAction = new JMenuItem(menuName);
    newAction.setActionCommand(actionCommand);
    newAction.addActionListener(ActionListenerFactory.createAction(actionCommand));
    DimensionMenu.add(newAction);
    ...
}

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See also:

• How to Use Actions tutorial.
• Concurrency in Swing lesson.
• Worker threads and SwingWorker to do database calls in a background thread and create/update Swing component in the Event Dispatch Thread