Thread: Java SnakeGame

Are those two files: a small, complete program that compiles, executes and shows the problem?

What is supposed to happen when the code is executed?
I get some green squares in the upper left and some red squares that jump around.

The code needs lots of debugging so you can see what it is doing when it executes. Try adding println() statements to the different methods to see where the code is executing or not executing.

Also you need to remove ALL the ONE TIME code from the paint() method. It should go in the class's constructor. With Swing classes, you should override paintComponent(), not paint().

Please post the code on the forum, not as an attachment.

Still the snake does not move when i press keys

Is the key listener method being called? Did the println() you put in that method print anything?

Copy the full text of the print outs and paste it here that shows how the code is executing.

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.image.BufferedImage;
import java.util.LinkedList;
import java.util.Random;
 
import javax.swing.JFrame;
import javax.swing.JPanel;
 
 
 
public class Game extends JPanel implements Runnable{
 
	private static final long serialVersionUID = 1L;
	private final int BOX_HEIGHT = 15;
	private final int BOX_WIDTH = 15;
	private final int GRID_WIDTH = 25;
	private final int GRID_HEIGHT = 25;
 
	private Key key;
	private boolean right = false, left = false, up = false, down = false;
 
	private LinkedList<Point> snake;
	private Point fruit;
 
	private Thread runThread;
	private Graphics globalGraphics;
	private int score = 0;
 
	public static void main(String[] args) {
		JFrame frame = new JFrame("Snake");
		Game game = new Game();
		frame.add(game);
		frame.setSize(406, 430);
		frame.setVisible(true);
		frame.setResizable(false);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		game.run();
	}
 
	public void paintComponent(Graphics g)
	{	if (runThread == null)
			{	this.setPreferredSize(new Dimension(406, 430));
				globalGraphics = g.create();
				key = new Key();
				addKeyListener(key);
				runThread = new Thread(this);
				runThread.start();
			}
		draw(globalGraphics);
	}
 
	public void GenerateDefaultSnake()
	{	score = 0;
		snake.clear();
 
		snake.add(new Point(5,4));
		snake.add(new Point(5,3));
		snake.add(new Point(5,2));
 
	}
 
	public void draw(Graphics g)
	{
		g.clearRect(0, 0, BOX_WIDTH * GRID_WIDTH + 10, BOX_HEIGHT * GRID_HEIGHT + 20);
 
		BufferedImage buffer = new BufferedImage(BOX_WIDTH * GRID_WIDTH + 10, BOX_HEIGHT * GRID_HEIGHT + 20, BufferedImage.TYPE_INT_ARGB);
		Graphics bufferGraphics = buffer.getGraphics();
 
		drawFruit(bufferGraphics);
		drawGrid(bufferGraphics);
		drawSnake(bufferGraphics);
		drawScore(bufferGraphics);
 
 
		g.drawImage(buffer, 0, 0, BOX_WIDTH * GRID_WIDTH + 10,  BOX_HEIGHT * GRID_HEIGHT + 20, this);
	}
 
public void move()
	{
		Point head = snake.peekFirst();
		Point newPoint = head;
 
		if(up == true){
			newPoint = new Point(head.x, head.y - 1);
		}
		if(down == true){
			newPoint = new Point(head.x, head.y + 1);
		}
		if(left == true){
			newPoint = new Point(head.x - 1, head.y);
		}
		if(right == true){
			newPoint = new Point(head.x + 1, head.y);
		}
 
		snake.remove(snake.peekLast());
 
		if (newPoint.equals(fruit))
		{
 
			score+=10;
 
			Point addPoint = (Point) newPoint.clone();
 
			if(up == true){
				newPoint = new Point(head.x, head.y - 1);
			}
			if(down == true){
				newPoint = new Point(head.x, head.y + 1);
			}
			if(left == true){
				newPoint = new Point(head.x - 1, head.y);
			}
			if(right == true){
				newPoint = new Point(head.x + 1, head.y);
			}
 
			snake.push(addPoint);
			placeFruit();
 
		}
		else if (newPoint.x < 0 || newPoint.x > (GRID_WIDTH - 1))
		{			
			return;
		}
		else if (newPoint.y < 0 || newPoint.y > (GRID_HEIGHT - 1))
		{		
			return;
		}
		else if (snake.contains(newPoint))
		{		
			return;
		}		
		snake.push(newPoint);
	}
 
	public void drawScore(Graphics g)
	{
		g.drawString("Score: " + score, 0, BOX_HEIGHT * GRID_HEIGHT + 10);
	}
 
	public void drawGrid(Graphics g)
	{
 
		g.drawRect(0, 0, GRID_WIDTH * BOX_WIDTH, GRID_HEIGHT * BOX_HEIGHT);
 
		for (int x = BOX_WIDTH; x < GRID_WIDTH * BOX_WIDTH; x+=BOX_WIDTH)
		{
			g.drawLine(x, 0, x, BOX_HEIGHT * GRID_HEIGHT);
		}
 
		for (int y = BOX_HEIGHT; y < GRID_HEIGHT * BOX_HEIGHT; y+=BOX_HEIGHT)
		{
			g.drawLine(0, y, GRID_WIDTH * BOX_WIDTH, y);
		}
	}
 
	public void drawSnake(Graphics g)
	{
		g.setColor(Color.GREEN);
		for (Point p : snake)
		{
			g.fillRect(p.x * BOX_WIDTH, p.y * BOX_HEIGHT, BOX_WIDTH, BOX_HEIGHT);
		}
		g.setColor(Color.BLACK);
	}
 
	public void drawFruit(Graphics g)
	{
		g.setColor(Color.RED);
		g.fillOval(fruit.x * BOX_WIDTH, fruit.y * BOX_HEIGHT, BOX_WIDTH, BOX_HEIGHT);
		g.setColor(Color.BLACK);
	}
 
	public void placeFruit()
	{
		Random rand = new Random();
		int randomX = rand.nextInt(GRID_WIDTH);
		int randomY = rand.nextInt(GRID_HEIGHT);
		Point randomPoint = new Point(randomX, randomY);
		while (snake.contains(randomPoint))
		{
			randomX = rand.nextInt(GRID_WIDTH);
			randomY = rand.nextInt(GRID_HEIGHT);
			randomPoint = new Point(randomX, randomY);
		}
		fruit = randomPoint;
	}
 
	public class Key implements KeyListener{
 
	@Override
	public void keyPressed(KeyEvent e) {
		int key = e.getKeyCode();
 
			if(key == KeyEvent.VK_UP && !down)
			{
				up = true;
				left = false;	
				right = false;
			}
 
			if(key == KeyEvent.VK_DOWN && !up)
			{
				down = true;
				left = false;	
				right = false;
			}
 
			if(key == KeyEvent.VK_LEFT && !right)
			{
				up = false;
				down = false;	
				left = true;
			}
 
			if(key == KeyEvent.VK_RIGHT && !left)
			{
				up = false;
				down = false;	
				right = true;
			}
 
		}
 
	@Override
	public void keyReleased(KeyEvent e) {
		// TODO Auto-generated method stub
 
	}	
 
	@Override
	public void keyTyped(KeyEvent e) {
		// TODO Auto-generated method stub
 
	}
	}
 
 
 
	@Override
	public void run() {
		while (true) {
			if (snake == null)
			{		snake = new LinkedList<Point>();	
					GenerateDefaultSnake();
					placeFruit();					
			}
			setPreferredSize(new Dimension(406, 430));			
			repaint();
			move();		
			try
			{
				Thread.currentThread();
				Thread.sleep(100);				
			}
			catch(Exception e)
			{
				e.printStackTrace();
			}	
		}
 
	}
 
}

Yeah, sorry, but when i tried at first to put all the code on forum, it did not work.

GenerateDefaultSnake
placeFruit
run
move
draw
run
move
drawFruit
drawGrid
drawSnake
drawScore
run
move
paintComponent
draw
drawFruit
drawGrid
drawSnake
drawScore
paintComponent

Where are the println() statements? You need to leave them in to show me how you were using them for debugging.

There still is code in the paintComponent() method that should NOT be there. Move the one time initialization code to the class's constructor. The same with code in the run() method. It should be in the constructor , not inside a loop in run().

Where is the full text of the print outs and paste it here that shows how the code is executing that I requested?

i get more and more erors.

If you want help with error messages, you should copy the full text and paste it here.

You need to set the component that has the listeners so that it can get the focus. The setFocusable method will do that.