Question

I’m a college student and this is my first time I have ever created a gui in Java. Right now I looked at this answer GUI in Java using Swing and followed the instructions and still nothing happens. Here is the code. I cut out all the irrelevant junk.

import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class Lab4Shell 
{
    // this holds the current game board
        private char[][] gameBoard = new char[7][8];
        private JButton[][] gameButtons = new JButton[7][8];

        private ImageIcon red = new ImageIcon("Red.jpg");
        private ImageIcon black = new ImageIcon("Black.jpg");
        private ImageIcon empty = new ImageIcon("Empty.jpg");

        private JPanel panel = new JPanel();

        private int currentPlayer = 1;
        private int numMoves = 0;
        //Why do you want everything in constructor?
        public Lab4Shell()
        {
            CreateWindow();
            ResetGame();



            // set layout
            // loop through buttons array creating buttons, registering event handlers and adding buttons to panel
            // add panel to frame
            // do other initialization of applet
        }

        public static void CreateWindow()
        {
            //Sets window title and create window object.
            JFrame aWindow = new JFrame("Connect Four");
            //Set window position and size
            aWindow.setBounds(500,100,400,400);
            //What close button does.
            aWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            //Make window visible.
            aWindow.setVisible(true);


        }

        public static void main(String args[])
        {
            SwingUtilities.invokeLater(new Runnable()
            {
                public void run()
                {

                    Lab4Shell game = new Lab4Shell();

                }
            });


        }
void ResetGame()
        {



            JLabel label = new JLabel();
            label.setIcon(empty);
            for(int r=0;r<gameBoard.length;r++)
            {
                java.util.Arrays.fill(gameBoard[r],0,gameBoard[r].length,'0');



                //loop through board columns
                for(int c=0;c<gameBoard[r].length;c++)
                {

                }

            }
            // loop through array setting char array back to ' ' and buttons array back to empty pic
            // reset currentPlayer and numMoves variables
        }

Answer 1

You’ve never adding anything to your frame – which is causing your problem. So in you createWindow method, you need to call:

aWindow.setContentPane(panel);

Then later on (like in your resetGame method), you’ll add your content (like the JLabel) to the panel:

panel.add(empty);

Where it’s added to your panel is determined by the LayoutManager of the panel (there are many of them – the default is BorderLayout)

Other helpful things:

• Generally, when it makes sense, create/initialize your objects in the constructor and add/remove/update them in the runtime.
• For troubleshooting, use the .setOpaque(true) and .setBackground(Color.blue) methods on what you want to see. If you don’t see it then, either something is covering it up, or it was never added

Good luck.