JFrame shows up grey, blank

Question

I have a problem where my frame shows up as grey, but then after a few seconds it displays the image as my for loop is finishing. I need to make it so that it displays the image correctly once it opens in order to show the loop. Here is my entire code, sorry about the length:

import java.awt.*;
import javax.swing.*;

public class MainFrame extends JFrame{
    public void MainFrame() {
        setTitle("Game");
        setSize(1300, 650);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
        setBackground(Color.WHITE);
        Dice diceObject = new Dice();
        add(diceObject);
    }
}
import java.awt.*;
import java.util.Random;
import javax.swing.*;


public class Dice extends JPanel {

 public static int pause(int n)
    {
        try {
            Thread.sleep(n);
            } catch(InterruptedException e) {
        }
        return n;
    }

public void Dice() {
    setDoubleBuffered(true);
}

@Override
public void paintComponent(Graphics g) {
    super.paintComponent(g);
    int width = getWidth();    
    int height = getHeight(); 

    int num = 0;
    for (int i = 0; i < 7; i++) {
        Random generator= new Random();
        int number = generator.nextInt(6)+1;
        g.setColor(Color.WHITE);
        g.fillRect(0, 0, width, height);
        g.setColor(Color.BLACK);
        g.drawRoundRect(550, 150, 200, 200, 50, 50);
        System.out.println("Test");
        if (number == 1) {                  //Roll one
            num = 1;
            g.setColor(new Color (0, 0, 0));
            g.fillOval(640, 240, 20, 20);
            pause(100);
        } if (number == 2) {                //Roll two
            num = 2;
            g.setColor(new Color (0, 0, 0));
            g.fillOval(590, 290, 20, 20);
            g.fillOval(690, 190, 20, 20);
            pause(100);
        } if (number == 3) {                //Roll three
            num = 3;
            g.setColor(new Color (0, 0, 0));
            g.fillOval(590, 290, 20, 20);
            g.fillOval(640, 240, 20, 20);
            g.fillOval(690, 190, 20, 20);
            pause(100);
        } if (number == 4) {                //Roll four
            num = 4;
            g.setColor(new Color (0, 0, 0));
            g.fillOval(590, 290, 20, 20);
            g.fillOval(590, 190, 20, 20);
            g.fillOval(690, 290, 20, 20);
            g.fillOval(690, 190, 20, 20);
            pause(100);
        } if (number == 5) {                //Roll five
            num = 5;
            g.setColor(new Color (0, 0, 0));
            g.fillOval(590, 290, 20, 20);
            g.fillOval(590, 190, 20, 20);
            g.fillOval(640, 240, 20, 20);
            g.fillOval(690, 290, 20, 20);
            g.fillOval(690, 190, 20, 20);
            pause(100);
        } if (number == 6) {                //Roll six
            num = 6;
            g.setColor(new Color (0, 0, 0));
            g.fillOval(590, 190, 20, 20);
            g.fillOval(590, 240, 20, 20);
            g.fillOval(590, 290, 20, 20);
            g.fillOval(690, 190, 20, 20);
            g.fillOval(690, 240, 20, 20);
            g.fillOval(690, 290, 20, 20);
            pause(100);
        }
    }
    g.setFont(new Font("TimesRoman", Font.PLAIN, 20));
    g.drawString("You rolled a " + num, 590, 100);
    pause(1000);
}
}

Thanks in advance.

Answer 1

The first problem is the fact that you are setting the frame visible BEFORE you add anything to it...

Instead, try calling setVisible last

public class MainFrame extends JFrame{
    public void MainFrame() {
        setTitle("Game");
        setSize(1300, 650);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBackground(Color.WHITE);
        Dice diceObject = new Dice();
        add(diceObject);
        setVisible(true);
    }
}

You should also avoid extending directly from JFrame as you're not adding any new functionality to the class and need to take into consideration Initial Threads and ensure you are starting the main UI within the context of the Event Dispatching Thread.

The rest of your problems relate to your previous question

Updated with working example

Cause I'm lazy, I've utilised the Graphics 2D API to draw the dots. I did this because many of the dots appear in the same locations for many of the numbers...

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Ellipse2D;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class DiceRoller {

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

    public DiceRoller() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new Die());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class Die extends JPanel {

        private int number = 1;

        public Die() {
            Timer timer = new Timer(500, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    number = (int) (Math.round((Math.random() * 5) + 1));
                    repaint();
                }
            });
            timer.setRepeats(true);
            timer.setInitialDelay(0);
            timer.start();
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(220, 220);
        }

        @Override
        public void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            int width = getWidth();
            int height = getHeight();

            g2d.setColor(Color.WHITE);
            g2d.fillRect(0, 0, width, height);
            g2d.setColor(Color.BLACK);
            g2d.drawRoundRect(10, 10, width - 20, height - 20, 50, 50);

            List<Shape> dots = new ArrayList<>(6);

            if (number == 1 || number == 3 || number == 5) {
                int x = (width - 20) / 2;
                int y = (height - 20) / 2;
                dots.add(new Ellipse2D.Float(x, y, 20, 20));
            }

            if (number == 2 || number == 3 || number == 4 || number == 5 || number == 6) {

                int x = ((width / 2) - 20) / 2;
                int y = ((height / 2) - 20) / 2;
                dots.add(new Ellipse2D.Float(x, y, 20, 20));
                dots.add(new Ellipse2D.Float(x + (width / 2), y + (height / 2), 20, 20));

            }

            if (number == 4 || number == 5 || number == 6) {

                int x = (width / 2) + (((width / 2) - 20) / 2);
                int y = ((height / 2) - 20) / 2;
                dots.add(new Ellipse2D.Float(x, y, 20, 20));
                dots.add(new Ellipse2D.Float(x - (width / 2), y + (height / 2), 20, 20));

            }

            if (number == 6) {

                int x = (((width / 2) - 20) / 2);
                int y = (height - 20) / 2;
                dots.add(new Ellipse2D.Float(x, y, 20, 20));
                dots.add(new Ellipse2D.Float(x + (width / 2), y, 20, 20));

            }

            for (Shape dot : dots) {
                g2d.fill(dot);
            }

            g2d.dispose();
        }
    }
}