Why is the global variable resetting or different for each button?

Question

I am making a tic tac toe game and I want to be able to have the button alternate x and o when clicked. Now they just are all x on the first click and all o on the second click. I tried with and without keyword this as well.

Here is the button class

public class Toebuttons extends JButton implements ActionListener
{
boolean x = true; // if true x's turn if false o's turn
int count = 0;
public Toebuttons()
{
   super("blank");
   this.addActionListener(this);
}
public void actionPerformed(ActionEvent e)
{
   if(this.x == true)
   {
       count++;
       System.out.println(count);
       setText("X");
       this.x = false;
   }
   else if(this.x == false)
   {
       count++;
       System.out.println(count);
       setText("O");
       this.x = true;
   }
  }
}

Here is the board class

public class ticTacBoard extends JFrame
{
Toebuttons toe[] = new Toebuttons[9];
public ticTacBoard()
{
    super("Tic tac board");
    setSize(500,500);
    setLayout(new GridLayout(3,3));
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setLocationRelativeTo(null);
    toFront();
    for(int i = 0; i<toe.length; i++)
    {
        toe[i] = new Toebuttons();
        add(toe[i]);
    }
    setVisible(true);
 }
}

Answer 1

Your problem is one of ineffective object-design: Each button has its own boolean x state which is independent from all the others, and this you should not do. In fact, you should have a Game object, one that holds the buttons and that is separate from the buttons, and that holds this state and controls the button's response to press based on this state.

Side note: I wouldn't extend JButton but rather would use JButtons.

For example, you could give all the JButtons the same ActionListener:

import java.awt.BorderLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;    
import javax.swing.*;

public class TicTacFoo extends JPanel {
    private static final long serialVersionUID = 1L;
    private static final int ROWS = 3;
    private static final Font BTN_FONT = new Font(Font.SANS_SERIF, Font.BOLD, 80);
    private JButton[][] buttons = new JButton[ROWS][ROWS];
    private boolean xTurn = true;
    private int count = 0;

    public TicTacFoo() {

        JPanel buttonPanel = new JPanel(new GridLayout(ROWS, ROWS));
        setLayout(new GridLayout(ROWS, ROWS));

        // single ActionListener for all buttons
        ButtonListener buttonListener = new ButtonListener();

        // create buttons in nested for loop
        for (int row = 0; row < buttons.length; row++) {
            for (int col = 0; col < buttons[row].length; col++) {
                buttons[row][col] = new JButton("   ");
                buttons[row][col].setFont(BTN_FONT);
                buttons[row][col].addActionListener(buttonListener);
                buttonPanel.add(buttons[row][col]);
            }
        }

        setLayout(new BorderLayout());
        add(buttonPanel);
        add(new JButton(new ResetAction()), BorderLayout.PAGE_END);
    }

    private class ButtonListener implements ActionListener {
        @Override
        public void actionPerformed(ActionEvent e) {

            // get the button that was pressed
            JButton buttonPressed = (JButton) e.getSource();
            String text = buttonPressed.getText().trim();
            if (!text.isEmpty()) {
                // button already has been pressed
                // so exit from the listener
                return;
            }

            if (xTurn) {
                buttonPressed.setText("X");
            } else {
                buttonPressed.setText("O");
            }

            int rowPressed = -1;
            int colPressed = -1;
            // which button pressed?
            for (int row = 0; row < buttons.length; row++) {
                for (int col = 0; col < buttons[row].length; col++) {
                    if (buttons[row][col] == buttonPressed) {
                        rowPressed = row;
                        colPressed = col;
                        break;
                    }
                }
            }

            // TODO: here code where you would test for win
            // ......

            // swap turn
            xTurn = !xTurn;
            // increment count:
            count++;
            System.out.printf("count: %d, [row, col]: [%d, %d]%n", count, rowPressed, colPressed);
        }
    }

    // resets program back to initial state
    @SuppressWarnings("serial")
    class ResetAction extends AbstractAction {
        public ResetAction() {
            super("Reset");
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            // loop through all buttons, resetting state back to initial
            for (JButton[] buttonRow : buttons) {
                for (JButton button : buttonRow) {
                    button.setText("   ");
                }
            }
            xTurn = true;
            count = 0;
        }
    }

    private static void createAndShowGui() {
        TicTacFoo mainPanel = new TicTacFoo();

        JFrame frame = new JFrame("TicTacFoo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(mainPanel);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> createAndShowGui());
    }
}

Answer 2

This is not C++ and this one

boolean x = true;

is not a global in Java. To mimic variable that can be understood as "global" (common for all class instances) in Java you need to declare it as static like

static boolean x = true;