Thread: Error while moving the tiles in frame

Hello! I was following a tutorial on how to make a game when i suddenly got an error concerning moving tiles. i get this error when i tried to use a and d to move:

Exception in thread "Display" java.lang.ArrayIndexOutOfBoundsException: 48600
at com.cherno.graphics.Screen.render(Screen.java:44)
at com.cherno.Game.render(Game.java:124)
at com.cherno.Game.run(Game.java:87)
at java.lang.Thread.run(Unknown Source)

I do not get the error while using w or s but the tiles are still not moving when pressing them.

I have three classes at work here.
The main, Game.java;

package com.cherno;
 
import java.awt.Canvas;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferStrategy;
import java.awt.image.BufferedImage;
import java.awt.image.DataBufferInt;
import javax.swing.JFrame;
import com.cherno.Game;
import com.cherno.graphics.Screen;
import com.cherno.input.Keyboard;
 
public class Game extends Canvas implements Runnable{
private static final long serialVersionUID = 1L;
 
	public static int width = 300;
	public static int height = width / 16 * 9;
	public static int scale = 3;
 
 
 
	private Thread thread;
	private JFrame frame;
	private Keyboard key;
	private boolean running = false;
 
	private Screen screen;
 
	private BufferedImage image= new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
	private int[] pixels = ((DataBufferInt)image.getRaster().getDataBuffer()).getData();
 
 
 
	public Game(){
		Dimension size = new Dimension(width * scale, height * scale);
		setPreferredSize(size);
 
		screen = new Screen(width, height);
		frame = new JFrame();
 
		key = new Keyboard();
		addKeyListener(key);
	}
 
 
 
	public synchronized void start(){
		running = true;
		thread = new Thread(this, "Display");
		thread.start();
 
	}
 
 
 
	public synchronized void stop(){
		running = false;
		try{
			thread.join();
		}catch(InterruptedException e){
            e.printStackTrace();		
 
		}
 
	}
 
 
 
	public void run(){
		long lastTime = System.nanoTime();
		long timer = System.currentTimeMillis();
		final double ns= 1000000000.0 / 60.0;
		double delta = 0;
		int frames = 0;
		int updates = 0;
		while (running){
			long now = System.nanoTime();
			delta=delta+=(now-lastTime)/ns;
			lastTime = now;
			while (delta >= 1){
				update();
				updates++;
				delta--;
			}
			render();
			frames++;
 
			if (System.currentTimeMillis() - timer > 1000){
				timer += 1000;
				//System.out.println(updates + "ups, " + frames + " fps");
				frame.setTitle("false rabbit " + "  |   "+updates + "ups, " + frames + " fps");
				updates=0;
				frames=0;
			}
		}
		stop();
	}
 
	public int x=0, y=0;
 
public void update(){
 
	key.update();
	if(key.up)y--;
	if(key.down)y++;
	if(key.left)x--;
	if(key.right)x++;
 
 
	}
 
 
 
	public void render(){
		BufferStrategy bs = getBufferStrategy();
		if (bs==null){
			createBufferStrategy(3);
			return;
		} 
 
		screen.clear();
		screen.render(x, 0);
 
		for (int i = 0; i < pixels.length; i++){
			pixels[i] = screen.pixels[i];
		}
 
		Graphics g = bs.getDrawGraphics();
 
		g.drawImage(image, 0, 0, getWidth(), getHeight(), null);
 
		g.dispose();
		bs.show();
	}
 
 
 
	public static void main(String[] args){
		Game game = new Game();
		game.frame.setResizable(false);
		//game.frame.setTitle("rabbit false");
		game.frame.add(game);
		game.frame.pack();
		game.frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		game.frame.setLocationRelativeTo(null);
		game.frame.setVisible(true);
 
		game.start();
	}
}

The class that mainly structures the "screen", Screen;

package com.cherno.graphics;
 
import java.util.Random;
 
public class Screen {
 
	private int width, height;
	public int[] pixels;
	public final int MAP_SIZE = 64;
	public final int MAP_SIZE_MASK = MAP_SIZE -1;
 
	public int[] tiles = new int[MAP_SIZE * MAP_SIZE];
 
	private Random random = new Random();
 
	public Screen(int width, int height){
		this.width = width;
		this.height = height;
		pixels = new int[width * height];
 
		for (int i = 0; i < MAP_SIZE * MAP_SIZE; i++){
			tiles[i] = random.nextInt(0xffffff);
		}
	}
 
 
 
	public void clear(){
		for (int i = 0; i < pixels.length; i++){
		pixels[i] = 0;
		}
		}
 
 
 
	public void render(int xoffset, int yoffset){
        for(int y = 0; y < height; y++){
        	int yy = y + yoffset;
        	//if (yy < 0 || yy >= height )break;
			for(int x = 0; x < width; x++){
			    int xx = x + xoffset;
				//if (xx < 0 || xx >= width )break;
			    int tileIndex = ((xx >> 4) & MAP_SIZE_MASK ) + ((yy >> 4) & MAP_SIZE_MASK) * MAP_SIZE;
			    pixels[xx + yy * width] = tiles[tileIndex];
			    //error uccurs when using a and d not w or s
 
			}
		}
	}
 
}

And at last The Key class that listens to my keystrokes, i present..
Keyboard;

package com.cherno.input;
 
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
 
public class Keyboard implements KeyListener{
 
	private boolean[] keys = new boolean[120];
	public boolean up, down, left, right;
 
	public void update(){
		up = keys[KeyEvent.VK_UP] || keys[KeyEvent.VK_W];
		down = keys[KeyEvent.VK_DOWN] || keys[KeyEvent.VK_S];
		left = keys[KeyEvent.VK_LEFT] || keys[KeyEvent.VK_A];
		right = keys[KeyEvent.VK_RIGHT] || keys[KeyEvent.VK_D];
 
 
	}
 
 
	public void keyPressed(KeyEvent e) {
		keys[e.getKeyCode()] = true;
	}
 
	public void keyReleased(KeyEvent e) {
		keys[e.getKeyCode()] = false;
	}
 
	public void keyTyped(KeyEvent e) {
 
	}
 
}

I am SO happy for answers!

The integer array 'pixels[]' in Screen.render() is being given an index value greater than the array has been initialized to hold. The offending index value is 48,600 which must be larger than the product width * height. Work backwards, find out what the product width * height is and determine how to either limit the element index values to one less than that value OR increase width * height to accommodate larger values, if required. Or use an ArrayList of Integers for pixel[] if the size of the pixel[] array is uncertain (I like this last suggestion the least, because it indicates the programmer doesn't know what's going on, and that's not good when working with graphics/pixels on a display surface.)

So the array "pixels" is been given a value of ((300/16*9)*300)= 50625 and that is certainly greater than 48,600

Isnt it the line;

pixels = new int[width * height];


that set the max value the array "pixel" can hold?

--- Update ---

In the main class i changed the line;

screen.render(x, 0);

to

screen.render(x, y);

this makes it crash with the same error when i press any fps move button(a,w,s,d) or any arrow button.
in the tutorial i am following that is the correct line

--- Update ---

FIXED IT!. the error i got were because i (from main class Game) sent x and y to Screen but Screen did not actually do anything with it. by changing xx to x and yy to y in Following line i have successfully done what i intended.;

pixels[xx + yy * width] = tiles[tileIndex];

created the error, butt changing to;

pixels[x + y * width] = tiles[tileIndex];

fixed it!

I removed this error by referring x and y in that line to those who Game is sending to Screen.

Thanks for the help!!