Question

Here is a Connect Four program I’m making. So far, I’m able to add checkers to empty (eligible) slots, alternating red and black each time. My code may be quite inefficient, as this is my first swing program. However, my only major problem is that I can’t really get the GUI to update after the empty slots are clicked on. I tried validate(), but that didn’t appear to do anything. Links to the images used in the program can be found below. Thanks so much for your help!

import java.awt.Container;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Scanner;

import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JLabel;

import javax.swing.*;

public class GameFrame extends JFrame {

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    frame = new GameFrame();
                    frame.setContentPane(new JLabel(new ImageIcon(getClass()
                            .getResource("675 x 588 Connect Four.png"))));
                    frame.addSlots();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */

    static GameFrame frame;
    private static Icon slotForButton;
    public static JButton slotButton;
    static private JButton[] slot = new JButton[42];
    static private String[] slotColor = new String[42];
    static boolean turn = true;
    static boolean legitClick;
    static String slotClicked;
    static int slotNum;
    static Container gamePane;

    public GameFrame() {
        setBounds(100, 100, 685, 622);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setResizable(false);
        super.setTitle("Connect Four by Joel Christophel");
    }

    void addSlots() {
        ButtonHandler bh = new ButtonHandler();
        gamePane = getContentPane();
        gamePane.setLayout(new GridLayout(6, 6));
        int counter = 0;

        for (JButton e : slot) {
            slot[counter] = makeSlot("white");
            slot[counter].setBorderPainted(false);
            slot[counter].setContentAreaFilled(false);
            slot[counter].setFocusPainted(false);
            slot[counter].setActionCommand(counter + "");
            slotColor[counter] = "white";

            slot[counter].addActionListener(bh);
            add(slot[counter]);

            counter++;
        }
    }

    static JButton makeSlot(String color) {

        if (color.equals("white")) {
            slotForButton = new ImageIcon(
                    GameFrame.class.getResource("Space.png"));
        }

        else if (color.equals("red")) {
            slotForButton = new ImageIcon(
                    GameFrame.class.getResource("Red Checker.png"));
        }

        else if (color.equals("black")) {
            slotForButton = new ImageIcon(
                    GameFrame.class.getResource("Black Checker.png"));
        }

        slotButton = new JButton(slotForButton);

        return slotButton;
    }

    private class ButtonHandler implements ActionListener {

        public void actionPerformed(ActionEvent e) {
            slotClicked = e.getActionCommand();

            GameFrame.legitClick(slotClicked);
        }

    }

    private static void changeTurn() {
        turn = !turn; // true is red's turn; false is black's
    }

    private static void legitClick(String slotClicked1) {
        legitClick = false;

        slotClicked = slotClicked1;
        Scanner numScan = new Scanner(slotClicked);
        slotNum = numScan.nextInt();

        try {
            if (!slotColor[slotNum + 7].equals("white")&&slotColor[slotNum].equals("white")) {
                legitClick = true;
            }
        }

        catch (ArrayIndexOutOfBoundsException t) {

            if (slotColor[slotNum].equals("white")) {
                legitClick = true;
            }
        }

        if (legitClick == true) {
            if (turn == true) {
                slot[slotNum] = makeSlot("red");
                slotColor[slotNum] = "red";
                System.out.println("Put " + slotColor[slotNum] + " checker     in slot number " + slotNum + ".");
            }

            else if (turn == false) {
                slot[slotNum] = makeSlot("black");
                slotColor[slotNum] = "black";
                System.out.println("Put " + slotColor[slotNum] + " checker      in slot number " + slotNum + ".");
            }

            gamePane.validate();
            GameFrame.changeTurn();
        }
        System.out.println(turn);
    }

}

https://i.stack.imgur.com/8cNB3.png 675 x 588 Connect Four.png

https://i.stack.imgur.com/6oX7A.png Black Checker.png

https://i.stack.imgur.com/cdF7u.png Red Checker.png

https://i.stack.imgur.com/JNT61.png Space.png

Answer 1

Two thingies, it appears to me that you doing wrong in your code.

• First do check the condition that you specifying inside your
  legitClick() method, no matter when you click, it always returns false (legitClick). Hence no change will appear to the view.
• It appears that you creating a new JButton inside a makeSlot(), which is not exactly what you want, you simply have to change the Icon for the respective JButton instead of creating a new one.

I had modified the code a bit, inside the makeSlot() method and legitClick() method, though you have to change the logic yourself to actually make it work as you wanted, since I don’t know how checkers work 🙁

import java.awt.Container;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Scanner;

import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JLabel;

import javax.swing.*;

public class GameFrame extends JFrame {

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    frame = new GameFrame();
                    frame.setContentPane(new JLabel(new ImageIcon(getClass()
                            .getResource("/image/675 x 588 Connect Four.png"))));
                    frame.addSlots();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */

    static GameFrame frame;
    private static Icon slotForButton;
    public static JButton slotButton;
    static private JButton[] slot = new JButton[42];
    static private String[] slotColor = new String[42];
    static boolean turn = true;
    static boolean legitClick;
    static String slotClicked;
    static int slotNum;
    static Container gamePane;

    public GameFrame() {
        setBounds(100, 100, 685, 622);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setResizable(false);
        super.setTitle("Connect Four by Joel Christophel");
    }

    void addSlots() {
        ButtonHandler bh = new ButtonHandler();
        gamePane = getContentPane();
        gamePane.setLayout(new GridLayout(6, 6));

        for (int counter = 0; counter < slot.length; counter++) {
            // Added by me.
            slot[counter] = new JButton();
            slot[counter].setIcon(makeSlot("white", counter));
            slot[counter].setBorderPainted(false);
            slot[counter].setContentAreaFilled(false);
            slot[counter].setFocusPainted(false);
            slot[counter].setActionCommand(counter + "");
            slotColor[counter] = "white";

            slot[counter].addActionListener(bh);
            add(slot[counter]);

            //counter++;
        }
    }

    static Icon makeSlot(String color, int index) {

        if (color.equals("white")) {
            slotForButton = new ImageIcon(
                    GameFrame.class.getResource("/image/Space.png"));
        }

        else if (color.equals("red")) {
            slotForButton = new ImageIcon(
                    GameFrame.class.getResource("/image/Red Checker.png"));
        }

        else if (color.equals("black")) {
            slotForButton = new ImageIcon(
                    GameFrame.class.getResource("/image/Black Checker.png"));
        }

        //slot[index].setIcon(slotForButton);

        return slotForButton;
    }

    private class ButtonHandler implements ActionListener {

        public void actionPerformed(ActionEvent e) {
            slotClicked = e.getActionCommand();

            GameFrame.legitClick(slotClicked);
        }

    }

    private static void changeTurn() {
        turn = !turn; // true is red's turn; false is black's
    }

    private static void legitClick(String slotClicked1) {
        legitClick = false;

        slotClicked = slotClicked1;
        Scanner numScan = new Scanner(slotClicked);
        slotNum = numScan.nextInt();

        try {
            if (slotColor[slotNum + 7].equals("white")&&slotColor[slotNum].equals("white")) {
                legitClick = true;
            }
        }

        catch (ArrayIndexOutOfBoundsException t) {

            if (slotColor[slotNum].equals("white")) {
                legitClick = true;
            }
        }

        /*
         * This variable is used to tell
         * makeSlot that the JButton at
         * this index is pressed. So
         * simply change the Icon for this
         * JButton, instead of adding a new 
         * JButton.
         */
        int index = Integer.parseInt(slotClicked1);

        if (legitClick == true) {
            if (turn == true) {
                slot[index].setIcon(makeSlot("red", index));
                slotColor[slotNum] = "red";
                System.out.println("Put " + slotColor[slotNum] + " checker     in slot number " + slotNum + ".");
            }

            else if (turn == false) {
                slot[index].setIcon(makeSlot("black", index));
                slotColor[slotNum] = "black";
                System.out.println("Put " + slotColor[slotNum] + " checker      in slot number " + slotNum + ".");
            }

            //gamePane.validate();
            GameFrame.changeTurn();
        }
        System.out.println(turn);
    }

}