Program java permainan ular

import javax.swing.*;
import java.awt.*;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.Random;
import java.util.ArrayList;

public class Snake extends JFrame implements ActionListener {

    private static final long serialVersionUID = 123654L;   // just to avoid compile warning
    // number of squares in the grid, size of each of them
    private static final int SIZE = 25, WIDTH = 20;
    // the labels for displaying the snake and its foods
    private SnakeLabel[][] label = new SnakeLabel[SIZE][SIZE];
    // arrayList containing all of the snake position (Labels)
    private SnakeList snakeList = new SnakeList();
    // the label displaying if I am running or not and the size of the snake
    private JLabel statusLabel = new JLabel("Initializing");
    // random number generator to find a new spot for a new food when I eat one
    private Random random = new Random();
    // if I am in a pause state or not
    boolean pause = false;
    // the button to switch from pause to not pause
    private JButton pauseResume = new JButton("Pause");
    // which direction I am running and where is my head
    private int directionX = 0, directionY = -1, headX, headY;
    // the refresh rate
    private int refreshRate;
    // The Timer that moves the Snake
    private Timer timer;

    Snake() {
        super("Snake Game");
        // to hold all the labels with a gap of 1 pixel
        JPanel panel = new JPanel(new GridLayout(SIZE, SIZE, 1, 1));
        // the same color as the Snake so the back will show a continuos snake
        panel.setBackground(Color.BLUE);
        panel.setBorder(BorderFactory.createLineBorder(Color.BLUE));
        // create all the JLabels
        initLabels(panel);

        // add the 4 foods
        initFood();
        // init the snake the length of a quarter of our size
        initSnake(SIZE / 4);
        add(panel, BorderLayout.CENTER);

        // label if I am running well and size of the snake
        statusLabel.setHorizontalAlignment(SwingConstants.CENTER);
        statusLabel.setOpaque(true);
        statusLabel.setBackground(Color.YELLOW);
        add(statusLabel, BorderLayout.NORTH);
        // listener so the pause button will work
        pauseResume.setForeground(Color.RED);
        pauseResume.addActionListener(this);
        add(pauseResume, BorderLayout.SOUTH);
        // general JFrame stuff its size and visible
        setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        setSize(SIZE * WIDTH - 5, SIZE * WIDTH - 5);
        setVisible(true);
        // start the thread that move the snakes
        refreshRate = 5000 / (snakeList.size() / 2);
        timer = new Timer(refreshRate, this);
        timer.start();
    }

    // to initialize the labels filling the grid
    // this method is called only once
    private void initLabels(JPanel p) {
        for(int j = 0; j < SIZE; j++) {
            for(int i = 0; i < SIZE; i++) {
                label[i][j] = new SnakeLabel(i, j);
                p.add(label[i][j]);
            }
        }

    }
    // to put the initial 4 food labels in 1/4 of the grid
    // this method will be called only once
    private void initFood() {
        // north/west at 1/4 of the grid
        int x = SIZE / 4;
        int y = x;
        label[x][y].setFood(true);
        // north east so x is the same delta from the end
        x = SIZE - x;
        label[x][y].setFood(true);
        // south/west
        y = x;
        x = SIZE / 4;
        label[x][y].setFood(true);
        // south east
        x = y;
        label[x][y].setFood(true);       
    }

    // to position the snake at the beginning of game
    private void initSnake(int length) {
        // the snake in the middle of everything initial size of length
        headX = SIZE / 2;
        headY = (SIZE / 2) - (length / 2);
        // declare these label as holding the snake
        // registering them in the arrayList
        for(int i = headY; i < headY + length; i++)
            snakeList.addLabel(label[headX][i]);
        // set the color for the first time
        snakeList.updateColor();
    }

    // run
    public void runSnake() {

        // wait according to snake length... determine an empiric way
        int oldRefreshRate = refreshRate;
        refreshRate = 5000 / (snakeList.size() / 2);
        // manage to have at least a minimum refresh rate
        if(refreshRate < 10)
            refreshRate = 10;
        // if refresh rate changed, update Timer delay
        if(oldRefreshRate != refreshRate)
            timer.setDelay(refreshRate);
       
        // if the "Pause" button was pushed go to next turn
        if(pause)
            return;
        // update snake head position
        headX += directionX;
        headY += directionY;
        // check if we are going out of bound
        if(headX < 0 || headX >= SIZE || headY < 0 || headY >= SIZE) {
            statusLabel.setText("Out of bound... length: " + snakeList.size());
            timer.stop();
            pauseResume.setEnabled(false);
            return;
        }
        // check if we are eating ourself
        if(label[headX][headY].isSnake) {
            statusLabel.setText("You eat yourself... length: " + snakeList.size());
            timer.stop();
            pauseResume.setEnabled(false);
            return;
        }
        // if we hit food
        if(label[headX][headY].isFood) {
            snakeList.updateHead();     // without updating tail
            // found new place for food
            for(;;) {
                int x = random.nextInt(SIZE);
                int y = random.nextInt(SIZE);
                // start again if new random place is already in the snake or is already food
                if(label[x][y].isFood)
                    continue;
                if(label[x][y].isSnake)
                    continue;
                // ok good dpot not used yet/// declare it as food
                label[x][y].setFood(true);
                break;
            }
        }
        else {
            snakeList.updateTail();     // first if I pass on my back
            snakeList.updateHead();
        }
        statusLabel.setText("Running... snake length: " + snakeList.size()
                + "    Refresh Rate: " + refreshRate + "/1000 sec");

    }
    // called when the pause/resume button is hit
    public void actionPerformed(ActionEvent e) {
        Object o = e.getSource();
        if(o == pauseResume) {
            // change the state
            pause = !pause;
            // update button text accordingly
            if(pause) {
                pauseResume.setText("Resume");
                timer.stop();
            }
            else {
                pauseResume.setText("Pause");
                timer.restart();
            }
            return;
        }
        else {    // it is the Timer if it is not the pauseResume button
            runSnake();
        }
    }
    // to run the whole damned thing
    public static void main(String[] args) {

        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new Snake();
            }
        });
    }
    // array list that contains the position taken by the snake
    private class SnakeList extends ArrayList<SnakeLabel> {
        private static final long serialVersionUID = 654321L;  // to avoid compile warning
        // the 2 colours of the snake
        private Color[] snakeColor = {new Color(0, 0, 255), new Color(75, 75, 255)};
        // for initial build when we install the snake first positions
        private boolean addLabel(SnakeLabel sl) {
            // flag the SnakeLabel as being part of the Snake
            sl.setSnake(true);
            // call father's method to add an object into the arrayList
            return add(sl);
        }
        // remove (make free) the tail of the snake
        private void updateTail() {
            SnakeLabel sl = remove(size() - 1);
            sl.setSnake(false);
        }
        // to update the head to new position
        private void updateHead() {
            // declare it as part of the snake
            label[headX][headY].setSnake(true);
            // add it to the head of the snake
            add(0, label[headX][headY]);
            // switch colors
            updateColor();
        }

        // to put 2 colours in the snake
        private void updateColor() {
            int len = size();
            // the head in black
            get(0).setBackground(Color.BLACK);
            // variation of blue for the others
            for(int i = 1; i < len; i++) {
                get(i).setBackground(snakeColor[i % snakeColor.length]);
            }
        }
    } // end of inner class SnakeList

    // specialized JLabel to keep coordinate X and Y and have a mouseListener if cliked
    private class SnakeLabel extends JLabel implements MouseListener{
        private static final long serialVersionUID = 123456L;   // to avoid compile warning
        // my coordinates on the Grid so the mouseListener can know where I am situate
        private int x, y;
        // init not food and not snake
        boolean isFood = false;         // not a food case
        boolean isSnake = false;        // not part of the snake
        // constructor
        SnakeLabel(int x, int y) {
            super("");
            // save my coordinates
            this.x = x; this.y = y;
            // opaque because I use background to represent myself
            setOpaque(true);
            // so I will react if I am cleicked
            addMouseListener(this);
            // default color
            setBackground(Color.WHITE);
        }
        // declares me as a food case or not
        private void setFood(boolean state) {
            isFood = state;
            // change color accordingly
            if(state)
                setBackground(Color.RED);       // food color
            else
                setBackground(Color.WHITE);     // regular color
        }
        // declares me as part of the snake or not
        private void setSnake(boolean state) {
            isSnake = state;
            // change my color accordingly
            if(state) {
                setFood(false);      // make it available again as food slot
                setBackground(Color.BLUE);
            }
            else {
                setBackground(Color.WHITE);
            }
        }

        // ok click on me I just chek for the Pressed event to react faster
        // (important when the snake goes very fast)
        public void mousePressed(MouseEvent e) {
            // so am I going vertically or horitonaly
            if(directionX == 0) {
                // if clicked on my same X nothing to do
                if(x == headX)
                    return;
                directionY = 0;                // stop updating Y
                // if clicked to my left
                if(x < headX) {
                    // update the way I am going
                    directionX = -1;
                }   
                else  {   // so to my rioght
                    directionX = +1;               
                }
            }
            else {                  // OK I am moving horizontaly
                if(y == headY)
                    return;
                directionX = 0;
                if(y < headY) {     // to my left
                    directionY = -1;
                }
                else {     // to my right
                    directionY = +1;
                }               
            }
        }
        // do not react to those but as I implement MouseListener have have to implement these
        public void mouseEntered(MouseEvent arg0) {}
        public void mouseExited(MouseEvent arg0) {}
        public void mouseClicked(MouseEvent arg0) {}
        public void mouseReleased(MouseEvent arg0) {}

    }  // end inner class SnakeLabel
}