Delay in displaying contents in JDialog

Question

Please have a look at the following code

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.List;
import java.util.ArrayList;

public class SendEmailForm extends JDialog {

    private JLabel to, cc, bcc, subject, account;
    private JTextField toTxt, ccTxt, bccTxt, subjectTxt;
    private JTextArea messageTxt;
    private JButton send;
    private JComboBox accountBox;
    private JScrollPane scroll;
    private GridBagLayout gbl;
    private GridBagConstraints gbc;

    public SendEmailForm() {
        //Declaring instance variables
        to = new JLabel("To: ");
        cc = new JLabel("CC: ");
        bcc = new JLabel("BCC: ");
        subject = new JLabel("Subject: ");
        account = new JLabel("Select an Account: ");

        toTxt = new JTextField(20);
        ccTxt = new JTextField(20);
        bccTxt = new JTextField(20);
        subjectTxt = new JTextField(20);

        messageTxt = new JTextArea(20, 50);
        messageTxt.setLineWrap(true);
        scroll = new JScrollPane(messageTxt);
        scroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
        scroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);

        accountBox = new JComboBox();
        accountBox.addItem("Yahoo");
        accountBox.addItem("GMail");
        accountBox.addItem("MSN");
        //accountBox.addItem("Yahoo");
        //accountBox.addItem("Yahoo");

        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout(new FlowLayout());

        send = new JButton("Send");
        send.addActionListener(new SendButtonAction());
        buttonPanel.add(send);

        //Creating thr GUI
        //GUI CREATION IS REMOVED IN THIS POST

        this.setTitle("Send Emails");
        this.setVisible(true);
        this.pack();
        this.setLocationRelativeTo(null);
        this.validate();
    }

    private class SendButtonAction implements ActionListener {

        public void actionPerformed(ActionEvent ae) {
            ProgressMonitor pm = new ProgressMonitor();
            //Retreiving the user name and password
            List userData = new ArrayList();

            EmailDBConnector emailCon = new EmailDBHandler();
            userData = emailCon.getUserNameAndPassword(
                    accountBox.getSelectedItem().toString().trim());

            String userName = userData.get(0).toString();
            String password = userData.get(1).toString();
            System.out.println(userName);
            System.out.println(password);

            pm.setVisible(true);

            SendEmail sendEmail = new SendEmail(toTxt.getText(), userName.trim(),
                    bccTxt.getText(), ccTxt.getText(), accountBox.getSelectedItem().toString().trim(), messageTxt.getText().trim(),
                    password.trim(), subjectTxt.getText());

            String result = sendEmail.send();
            //pm.dispose();
            JOptionPane.showMessageDialog(null, result);
        }
    }

    private class ProgressMonitor extends JDialog {

        public ProgressMonitor() {
            this.setLayout(new BorderLayout());
            JLabel text = new JLabel("Sending..Please wait...");
            this.add(text, "Center");
            this.pack();
            this.validate();
            this.setLocationRelativeTo(null);
        }
    }
}

First, this is an email program. In here, when the JDialog is called, it just opens as a 100% blank window. I have added a JLabel, but it is not there when it is displaying. Anyway, it takes sometime to send the email, after the email is sent, I can see the JLabel in the JDialog. If I take my issue into one sentence, I am calling the JDialog before the email is sent, but it appears blank, after the email is sent, it's content are there! Why is this? Please help!

You don't need to call `validate()`. And I would `pack()`the contents before calling `setVisible(true)`. — Gilberto Torrezan, Sep 28 '12 at 15:37

mKorbel · Answer 1 · 2012-09-28T16:42:36.270

your code isn't an SSCCE, then

1.SendEmailForm();

remove this.validate();
move this.setVisible(true); as last code line
move this.pack(); before this.setVisible(true);
move this.setLocationRelativeTo(null); before this.setVisible(true);

2.public ProgressMonitor() { coud be

code

    private class ProgressMonitor extends JDialog {

        public ProgressMonitor() {
            setLayout(new BorderLayout());
            JLabel text = new JLabel("Sending..Please wait...");
            add(text, "Center");
            pack();
            setLocationRelativeTo(null);
            SwingUtilities.invokeLater(new Runnable() {

                @Override
                public void run() {
                    setVisible(true);
                }
            });
        }
    }

.

3.rest isn't clear from your question

are JComponents added to the visible container, then last code lines should be (re)validate() and repaint()
reuse JDialog for next action, set HIDE_on_CLOSE as default close operation for JDialog
don't extend JDialog, create this contianer as local variable, then you can call only (my)JDialog.setVisible(true) on next action (wrapped in invokeLater())

for your last bullet of point 1 ( _move this.setLocationRelativeTo(null); before this.pack();_ ), I disagree. If the purpose of that call is to center the window on the screen, then `pack()` should definitely be called before, otherwise the `setLocationRelativeTo(null)` will place the top-left corner in the center of the screen since `getSize()` will return (0,0). Calling `pack()` before ensures that the window has the appropriate size. — Guillaume Polet, Sep 28 '12 at 16:20
Thanks for the reply. But, when the invoke later is given, the window appears after the mail is sent!Please help — PeakGen, Sep 28 '12 at 17:23
read this thread please http://stackoverflow.com/questions/12641887/swingworker-in-java — mKorbel, Sep 28 '12 at 17:29

score 0 · Answer 2 · answered Sep 28 '12 at 15:50

You have created a number of components but have not added them to the JFrame in your application. As you are using GrigBagLayout, you will need to set the constraints for each component, e.g.:

subject = new JLabel("Subject: ");
gbc.fill = GridBagConstraints.BOTH;
gbc.weightx = 1.0;
gbl.setConstraints(subject, gbc);
add(subject);

Also don't forget to instantiate the layout & constraints first:

private GridBagLayout gbl = new GridBagLayout();
private GridBagConstraints gbc = new GridBagConstraints();

Delay in displaying contents in JDialog

2 Answers2