记录在JButton网格中按下的最后一个JButton

Question

Hey guys here's the deal I am trying to create a simple chess game using java. I have my board of an [8][8] array of JButtons. I assign each a new SquareListener which is a class that extends BoardListner which a super class that implements Action Listener. I want to record whether or not the button that is currently being pressed is equal to the last button that was pressed. I am storing the JButton instance that is pressed in the super class and referring to that in the SqaureListener actionPerformed method. Here is the example of the classes that I created for the buttons.

public class SquareListener extends BoardListener {
private int row;
private int column;


public SquareListener(int row, int column){
    this.setRow(row);
    this.setColumn(column);
}

@Override
public void actionPerformed(ActionEvent ae){
    JButton buttonPressed = (JButton) ae.getSource();
    if(buttonPressed == super.lastButtonPressed){
        System.out.println("This is the button you last pressed");
    }else{
        System.out.println("This is a new button");
    }
    super.lastButtonPressed = buttonPressed;
}

and here is the super class where I am storing the isSelecting data

public class BoardListener implements ActionListener {

    private boolean isSelectingInsteadOfTargeting = true;
    JButton lastButtonPressed = new JButton();

    @Override
     public void actionPerformed(ActionEvent arg0) {
    // TODO Auto-generated method stub
    }

    public boolean isSelectingInsteadOfTargeting() {
        return isSelectingInsteadOfTargeting;
    }

    public void setSelectingInsteadOfTargeting(boolean isSelectingInsteadOfTargeting) {
    this.isSelectingInsteadOfTargeting = isSelectingInsteadOfTargeting;
    }

}

I would expect for each time a button is pressed to have a instance of that button passed into buttonPressed and compared to what's stored in BoardListener, to then have that printed out and then to assign buttonPressed to the super member. Instead I am getting the behavior where if I press a button once it will always return "This is the button you last pressed" even If I had pressed a new one in between. Is there something wrong with the way I'm going about this? Is there any easier way?

here is the additional code where I store the buttons and assign them the action listeners

public Board(boolean _isWhite){
    gui = new JPanel(new GridLayout(8,8));
    chessBoardSquares = new Square[8][8];
    boolean shouldBeWhite = true;
    for(int i = 0; i < 8; i++){
        for(int j= 0; j < 8; j++){
            Square square = new Square(i,j);
            square.getButton().addActionListener(new SquareListener(i,j));
            if(shouldBeWhite){
                square.getButton().setBackground(Color.WHITE);
                shouldBeWhite = false;
            }else{
                square.getButton().setBackground(Color.BLACK);
                shouldBeWhite = true;
            }
            if (j == 7){
                shouldBeWhite = !shouldBeWhite;
            }
            chessBoardSquares[i][j] = square;
            gui.add(chessBoardSquares[i][j].getButton());
        }
    }
    BoardFactory boardFactory = new BoardFactory();
    if(_isWhite){
        updateBoardIconsBasedOnCurrentBoardArray(boardFactory.getBlackStartArray());
    }else{
        //getblack start array and invoke method to change button icons based on array
    }
}

Answer 1

We don't need a whole grid of 8 x 8, but maybe a 2 x 2 that can be scaled to 8 x 8 by you.

This code compares the last coords of the button clicked.

You might use a single ActionListener for all your buttons...

For example:

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class TwiceButtonPressed {

    private JFrame frame;

    private JButton[][] buttons;

    private JLabel label;
    private JLabel sameButtonLabel;

    private JPanel pane;

    private boolean sameButtonPressed;

    private static final int rows = 2;
    private static final int cols = 2;

    private int buttonRow = -1;
    private int buttonCol = -1;

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

    public void createAndShowGui() {
        frame = new JFrame(getClass().getSimpleName());

        sameButtonPressed = false;

        label = new JLabel("Button pressed: NONE");
        sameButtonLabel = new JLabel("Same button pressed: " + sameButtonPressed);

        pane = new JPanel();
        pane.setLayout(new GridLayout(rows, cols));

        buttons = new JButton[rows][cols];

        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                buttons[i][j] = new JButton(i + "" + j);
                buttons[i][j].addActionListener(listener);
                pane.add(buttons[i][j]);
            }
        }

        frame.add(sameButtonLabel, BorderLayout.NORTH);
        frame.add(pane, BorderLayout.CENTER);
        frame.add(label, BorderLayout.SOUTH);

        frame.pack();
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    public ActionListener listener = new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            for (int i = 0; i < rows; i++) {
                for (int j = 0; j < cols; j++) {
                    if (e.getSource().equals(buttons[i][j])) {
                        label.setText("Button pressed: " + buttons[i][j].getText());
                        System.out.println(buttonRow + "==" + i + "***" + buttonCol + "==" + j);
                        if (buttonRow == i && buttonCol == j) {
                            sameButtonPressed = true;
                        } else {
                            sameButtonPressed = false;
                        }
                        sameButtonLabel.setText("Same button pressed: " + sameButtonPressed);
                        buttonRow = i;
                        buttonCol = j;
                    }
                }
            }
        }
    };
}

Also, you might change your white / black algorithm to something like this:

for (int i = 0; i < rows; i++) {
    for (int j = 0; j < cols; j++) {
        buttons[i][j] = new JButton() {
            @Override
            public Dimension getPreferredSize() {
                return new Dimension(50, 50);
            }
        };
        buttons[i][j].addActionListener(listener);
        if (i % 2 == 0) {
            if (j % 2 == 0) {
                buttons[i][j].setBackground(Color.BLACK);
            } else {
                buttons[i][j].setBackground(Color.WHITE);
            }
        } else {
            if (j % 2 != 0) {
                buttons[i][j].setBackground(Color.BLACK);
            } else {
                buttons[i][j].setBackground(Color.WHITE);
            }
        }
        pane.add(buttons[i][j]);
    }
}

Answer 2

Each button has its own listener, and each listener has its own lsstButonPressed field, so that can't work.

Use the same listener instance for all buttons, or store the last button pressed in the board (or in another object shared by all the listeners).

Also, you don't need super to access the lastButtonPressed.

And this

JButton lastButtonPressed = new JButton();

creates a new JButton for nothing. Just leave the field to null.