Showing a popup in Swing indicating progress of program startup

Question

I have a JFrame class where it's constructor will take a little bit of time (in some occasions) to create all the appropriate objects.

What I want to do is before the main panel shows I will have a popup named toaster where it is going to say at which phase of the program execution I am. Here is my constructor:

public class GUI extends javax.swing.JFrame {        
    public GUI() {
        JOptionPane toasterPane = new JOptionPane(null,
                JOptionPane.INFORMATION_MESSAGE,
                JOptionPane.DEFAULT_OPTION,
                null,
                new Object[]{},
                null);

        JDialog toaster = new JDialog();
        toaster.setTitle("Loading...");
        toaster.setModal(false);
        toaster.setContentPane(toasterPane);
        toaster.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
        toaster.pack();
        toaster.setVisible(true);

        toasterPane.setMessage("Initializing Components...");
        initComponents();

        toasterPane.setMessage("Redirecting Console...");
        _mc = new MessageConsole(jMessageConsoleTextPane, true);
        _mc.redirectOut(null, null);
        _mc.redirectErr(Color.RED, null);
        _mc.setMessageLines(100);

        toasterPane.setMessage("Connecting To Database...");
        _user = new User("root", "");
        _connector = new Connector(_user, "localhost", 3306);
        _database = new SQLDatabase("testing", _connector);        
        updateComboBoxes();

        toaster.setVisible(false);
    }
//rest of the code here
}

The problem now is, that instead of showing me the messages it shows just this:

and the moment the program has loaded then it will show the last message (you can see that by commenting out the toaster.setVisible(false)) like this:

So any idea what am I doing wrong here?

Answer 1

You are blocking the Event Dispatch Thread (EDT) so the GUI can't repaint itself until the database access has finished executing. Basically you need to use a separate Thread to access the database.

Read the section from the Swing tutorial on Concurrency for more information and a solution that uses a Swing Worker.