Java, How to swap position of components horizontally and vertically in a GridLayout?

Question

I've gotten an assignment to create a 15 puzzle game. Where the player only can swap a tile of number if the blank tile is next to it horizontally or vertically. I believed that my solution to this was to create a Gridlayout 4x4. And a 2d array to find the location of a specific Button so I then can swap the buttons locations with each other if that makes any sense...

The problem is when I use panel.add(button0, row, col). It doesn't have x and y locations like a 2d array has, which I thought it did. It caused the button to end up on wrong places.

How can I use what I have so far to solve my problem or do I have to start over?

Thanks in advance!

class GameTest extends JFrame implements ActionListener{

JPanel panel = new JPanel();
JButton[][] buttons = new JButton[4][4];
JButton button0 = new JButton("EMPTY");

public GameTest() {
    add(panel);
    setBackground(Color.RED);
    panel.setLayout(new GridLayout(4,4));
    int i = 1;
    for (int row = 0; row < buttons.length; row++) {
        for (int col = 0; col < buttons.length; col++ ) {
            if (row == 3 && col == 3) {
                buttons[row][col] = button0;
                panel.add(buttons[row][col]);
                buttons[row][col].setBackground(Color.WHITE);
                buttons[row][col].setName("button0");
            }
            else{
                buttons[row][col] = new JButton(i + "");
                panel.add(buttons[row][col]);
                buttons[row][col].addActionListener(this);
                buttons[row][col].setBackground(Color.RED);
                buttons[row][col].setName("button" + i);
                buttons[row][col].setFont(new Font("Arial", Font.PLAIN, 30));
                i++;
            }
        }
    }
    setCursor(new Cursor(Cursor.HAND_CURSOR));
    setResizable(false);
    setLocation(500,200);
    setSize(400,400);
    setVisible(true);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
}


public boolean isSwappable(JButton button) {
    for (int row = 0; row < buttons.length; row++) {
        for (int col = 0; col < buttons.length; col++ ) {
            if (buttons[row][col] == button) {
                if (row != 3 ) {
                    if (buttons[row+1][col] == button0){
                        return true;
                    }
                }
                else if (col != 3){
                    if (buttons[row][col+1] == button0){
                        return true;
                    }
                }
                else if (row != 0) {
                    if (buttons[row-1][col] == button0) {
                        return true;
                    }
                }
                else if (col != 0) {
                    if ( buttons[row][col-1] == button0){
                        return true;
                    }
                }
            }
        }
    }
    return false;
}

@Override
public void actionPerformed(ActionEvent e) {
    JButton source = (JButton)e.getSource();
    if (isSwappable(source)) {
        int x = 0;
        int y = 0;
        JButton buttonTemp = null;
        JButton buttonTemp0 = null;
        for (int row = 0; row < buttons.length; row++) {
            for (int col = 0; col < buttons.length; col++) {
                if (buttons[row][col] == source) {
                    buttonTemp = source;

                    buttonTemp0 = button0;
                    x = row;
                    y = col;

                }
                if (buttons[row][col] == button0) {
                    buttons[row][col] = buttonTemp;
                    buttons[x][y] = buttonTemp0;
                }
            }
        }
    }
  }
}

Answer 1

It doesn't have x and y locations like a 2d array has,

Correct, it is a 1D array.

So you need to calculate the index using the 2D information.

So for example if you want to swap location of row = 1 and column = 2

The index would be:

int index = (row * 4) + column;