Puzzle

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.CropImageFilter;
import java.awt.image.FilteredImageSource;

import javax.swing.Box;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;


public class Puzzle extends JFrame implements ActionListener {

private JPanel centerPanel;
private JButton button;
private JLabel label;
private Image source;
private Image image;
int[][] pos;
int width, height;

public Puzzle() {

pos = new int[][] {
{0, 1, 2},
{3, 4, 5},
{6, 7, 8},
{9, 10, 11}
};


centerPanel = new JPanel();
centerPanel.setLayout(new GridLayout(4, 4, 0, 0));

ImageIcon sid = new ImageIcon(Puzzle.class.getResource("b3.jpg"));
source = sid.getImage();

width = sid.getIconWidth();
height = sid.getIconHeight();


add(Box.createRigidArea(new Dimension(0, 5)), BorderLayout.NORTH);
add(centerPanel, BorderLayout.CENTER);


for ( int i = 0; i < 4; i++) {
for ( int j = 0; j < 3; j++) {
if ( j == 2 && i == 3) {
label = new JLabel("");
centerPanel.add(label);
} else {
button = new JButton();
button.addActionListener(this);
centerPanel.add(button);
image = createImage(new FilteredImageSource(source.getSource(),
new CropImageFilter(j*width/3, i*height/4, (width/3)+1, height/4)));
button.setIcon(new ImageIcon(image));
}
}
}

setSize(325, 275);
setTitle("Puzzle");
setResizable(false);
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
setVisible(true);
}


public static void main(String[] args) {

new Puzzle();

}

public void actionPerformed(ActionEvent e) {
JButton button = (JButton) e.getSource();
Dimension size = button.getSize();

int labelX = label.getX();
int labelY = label.getY();
int buttonX = button.getX();
int buttonY = button.getY();
int buttonPosX = buttonX / size.width;
int buttonPosY = buttonY / size.height;
int buttonIndex = pos[buttonPosY][buttonPosX];



if (labelX == buttonX && (labelY - buttonY) == size.height ) {

int labelIndex = buttonIndex + 3;

centerPanel.remove(buttonIndex);
centerPanel.add(label, buttonIndex);
centerPanel.add(button,labelIndex);
centerPanel.validate();
}

if (labelX == buttonX && (labelY - buttonY) == -size.height ) {

int labelIndex = buttonIndex - 3;
centerPanel.remove(labelIndex);
centerPanel.add(button,labelIndex);
centerPanel.add(label, buttonIndex);
centerPanel.validate();
}

if (labelY == buttonY && (labelX - buttonX) == size.width ) {

int labelIndex = buttonIndex + 1;

centerPanel.remove(buttonIndex);
centerPanel.add(label, buttonIndex);
centerPanel.add(button,labelIndex);
centerPanel.validate();
}

if (labelY == buttonY && (labelX - buttonX) == -size.width ) {

int labelIndex = buttonIndex - 1;

centerPanel.remove(buttonIndex);
centerPanel.add(label, labelIndex);
centerPanel.add(button,labelIndex);
centerPanel.validate();
}
}
}