SwingWorker不会更新JTable

Question

I have a class of my SwingWorker where I want to update data in JTable from :

public class MySwingWorker extends SwingWorker<Void, Monitor> {


    public DBMonitor dbmonitor;  
    Vector<Vector> rowData;
    Vector<String> columnNames;
    DefaultTableModel model;
    Monitor obj;

    @Override
    protected Void doInBackground() throws Exception {

        dbmonitor = new DBMonitor();
        rowData = dbmonitor.getJobsData();
        columnNames = dbmonitor.getColumnNames();
        obj.setJTable(rowData, columnNames);

        while (!isCancelled()) {
            Thread.sleep(10000);
            JOptionPane.showMessageDialog(null, "SLEEP!");
            rowData = dbmonitor.getJobsData();
            columnNames = dbmonitor.getColumnNames();
            model = new DefaultTableModel(rowData, columnNames);
            publish(new Monitor(model));
        }
        return null;
    }

    @Override
    protected void process(List<Monitor> monitors) {
        Monitor monitor = monitors.get(monitors.size() - 1);
        monitor.updateJTable(monitor.getModel());
    }

}

And Monitor class where I render Tabs , JTable and execute SwingWorker :

public class Monitor extends JFrame{

    TableModel model;
    JTable jtable = null;
    JTabbedPane jtp = null;
    JPanel jp1 = null;
    JPanel jp2 = null;
    JLabel label1 = null;
    JLabel label2 = null;

    MySwingWorker worker;

    public void setJTable(Vector data, Vector columnNames) {

        jtable = new JTable(data, columnNames);
        JScrollPane scrollPane = new JScrollPane(jtable);
        jp1.add(scrollPane);
    }

    public void updateJTable(TableModel model) {
        jtable = new JTable(model);
    }

    public Monitor() throws ClassNotFoundException, SQLException {

        setTitle("Monitor System");
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        //Panel with tabs for navigation
        jtp = new JTabbedPane();
        getContentPane().add(jtp);

        //tab1, info from dba_jobs
        jp1 = new JPanel();

        //tab2 info from QueueInfo
        jp2 = new JPanel();
        label1 = new JLabel();
        label1.setText("tab1");

        label2 = new JLabel();
        label2.setText("tab2");

        jp1.add(label1);
        jp2.add(label2);

        jtp.add("Tab1", jp1);
        jtp.add("Tab2", jp2);

        DBMonitor dbmonitor = new DBMonitor();
        Vector<Vector> rowData = dbmonitor.getJobsData();
        Vector<String> columnNames = dbmonitor.getColumnNames();

        setJTable(rowData, columnNames);
        setSize(600, 600);
        setVisible(true);

        (worker = new MySwingWorker()).execute();
    }

    public Monitor(TableModel model) {
        this.model = model;
    }

    public TableModel getModel() {
        return model;
    }

}

And in my Main method I execute:

SwingUtilities.invokeLater(new Runnable() {

    @Override
    public void run() {
        new Monitor(); 
    }
});

The problem is that, showMessageDialog() doesn't append, and JTable doesn't refresh. I want update JTable from every 10 sec. The Example I take from here

Answer 1

Your JTable does not update because when publishing you create a new JFrame (called Monitor) and set the new TableModel to it. You never show the new JFrame , nor do you update the already existing one. Hence, of course, you won't see any updates.

As for how to do this properly:

• You need to give your SwingWorker either a callback or a reference to the already existing Monitor (explicit via a variable, or implicit by moving it into an inner class). Only then will you update the correct JFrame
• Even then, you are creating a new JTable every time your model changes and not replacing your component. IE your frame will still show the old table and have the data for a new one (but will not show it). You need to either replace the table in the updateTable method, or ( much better solution ) update the model.

EDIT

An example of how this can look like (Assuming your column names don't change, if they do send them over just like the rows):

public class Monitor extends JFrame{

    TableModel model;
    Vector<String> columnNames;
    <other components>
    public Monitor() throws SQLException {
        columnNames = dbmonitor.getColumnNames();
        model = new DefaultTableModel(columnNames, 0);
        <Add all components, including table with the created table model>
        (worker = new MySwingWorker()).execute();
    }

    private class MySwingWorker extends SwingWorker<Void, Vector<Vector>> {
         @Override
         protected Void doInBackground() throws Exception {
             dbmonitor = new DBMonitor();
             rowData = dbmonitor.getJobsData();

             while (!isCancelled()) {
                 Thread.sleep(10000);
                 publish(dbmonitor.getJobsData());
             }
             return null;
          }

          @Override
          protected void process(List<Vector<Vector>> data) {
              Vector<Vector> lastPublish = data.get(data.size() - 1);
              tableModel.setDataVector(lastPublish, columnNames);
          }
    }
}