Program shows an empty window

Question

I have started a program in JAVA and SOMETIMES, when I run it or debug it, it shows an empty white window. I have no idea why, but I redebug it and it shows the window correctly. Btw, it has nothing to do with the mysql connect void at the end.

Here is the code:

package com.hinx.client;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import java.sql.*;


public class Main {

public static void main(String [] args) 
{
    createWindow();
}


static void createWindow()
{


    //Create panel
    JPanel content = new JPanel();
    content.setLayout(null);
    //Build the frame
    JFrame frame = new JFrame("Hinx - A marketplace for apps - Client ALPHA_0.0.1");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(700, 233);
    frame.setResizable(false);
    frame.setLocationRelativeTo(null);
    frame.add(content);
    frame.setVisible(true);

    //Create username label
    JLabel username = new JLabel("Username:");
    username.setFont(new Font("Arial", Font.BOLD, 15));
    username.setForeground(Color.white);
    username.setBounds(34, 8, 100, 50);

    //Create password label
    JLabel password = new JLabel("Password:");
    password.setFont(new Font("Arial", Font.BOLD, 15));
    password.setForeground(Color.white);
    password.setBounds(36, 85, 100, 50);

    //Create username field
    JTextField usernamet = new JTextField(20);
    usernamet.setBounds(12, 50, 125, 30);
    usernamet.setBorder(javax.swing.BorderFactory.createEmptyBorder());

    //Create password field
    JTextField passwordt = new JTextField(20);
    passwordt.setBounds(12, 125, 125, 30);
    passwordt.setBorder(javax.swing.BorderFactory.createEmptyBorder());

    //Add the login button
    JButton login = new JButton("Login");
    login.setBounds(0, 175, 150, 30);
    login.addActionListener(new ActionListener(){
        public void actionPerformed(ActionEvent e) {

        }
    });

    //Create login panel
    JPanel loginpanel = new JPanel();
    loginpanel.setLayout(null);
    loginpanel.setBounds(0, 0, 150, 400);
    loginpanel.setBackground(Color.gray);

    //Add the items to the loginpanel
    loginpanel.add(username);
    loginpanel.add(password);
    loginpanel.add(usernamet);
    loginpanel.add(passwordt);
    loginpanel.add(login);

    //Add the items to the content panel
    content.add(loginpanel);
}

protected void connect()
{
    String driver = "com.mysql.jdbc.Driver";
    String dbadress = "";
    String dbname = "";
    String username = "";
    String password = "";
    try
    {
        Class.forName(driver).newInstance();
        Connection conn = DriverManager.getConnection(dbadress+dbname, username,password);
        Statement st = conn.createStatement();

    } catch (Exception e) {
        e.printStackTrace();
    }
}

}

`content.setLayout(null);` Didn't we address that in your **last** question? — Andrew Thompson, May 03 '13 at 15:03
Usin null-Layout is really fighting the system. It leads to horrible code, very hard to maintain, impossible bugs etc... Use them appropriately and they will ease your day. — Guillaume Polet, May 03 '13 at 15:07
I just realized the frame size is too small to display the components where you have placed them. More fuel to the 'use layouts and `pack()` the GUI' argument. — Andrew Thompson, May 03 '13 at 15:13
I'm vote to exact duplicate, [again the same problems, by three answerers described on another post](http://stackoverflow.com/q/16360418/714968) — mKorbel, May 03 '13 at 15:27

score 2 · Accepted Answer · answered May 03 '13 at 15:01

2

frame.setVisible(true);

make it the last statement, after you add all the components to the JFrame.

Also, it is generally a best practice to do any swing-related code in the GUI-thread (EDT):

public static void main(String[] args)
{
    SwingUtilities.invokeLater(new Runnable()
    {
        @Override
        public void run()
        {
            createWindow();
        }
    });
}

answered May 03 '13 at 15:01

Eng.Fouad

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I see the frame, but sometimes, I dont see the content in it. I just see everything white. – James L. May 03 '13 at 15:03
I added set visible at the end. Looks like it's working. Thank you! – James L. May 03 '13 at 15:05

score 2 · Answer 2 · answered May 03 '13 at 15:02

2

Swing GUIs should be started on the Event Dispatch Thread. See Initial Threads for more details.

answered May 03 '13 at 15:02

Andrew Thompson

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score 1 · Answer 3 · answered May 03 '13 at 15:06

1

Invoke frame.setVisible(true); at the end of your method ( after adding all the components to panel)

answered May 03 '13 at 15:06

Laksitha Ranasingha

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oops... while I am typing Eng.Fouad answered the question ;) – Laksitha Ranasingha May 03 '13 at 15:08

Program shows an empty window

3 Answers3