I'm a newbie in Java and just tried a tutorial of zetcode.com. He is explaining and showing in his Tutorial how to create a simple brickbreaker game, I read his tutorial and programmed the game as he did. At the end it wasnt working. the error is:
Exception in thread "main" java.lang.NullPointerException at javax.swing.ImageIcon.(ImageIcon.java:205) at breakout.Ball.(Ball.java:14) at java.awt.Container.addNotify(Container.java:2769) at javax.swing.JComponent.addNotify(JComponent.java:4741) at java.awt.Container.addNotify(Container.java:2769) at javax.swing.JComponent.addNotify(JComponent.java:4741) at java.awt.Container.addNotify(Container.java:2769) at javax.swing.JComponent.addNotify(JComponent.java:4741) at javax.swing.JRootPane.addNotify(JRootPane.java:756) at java.awt.Container.addNotify(Container.java:2769) at java.awt.Window.addNotify(Window.java:770) at java.awt.Frame.addNotify(Frame.java:487) at java.awt.Window.show(Window.java:1031) at java.awt.Component.show(Component.java:1651) at java.awt.Component.setVisible(Component.java:1603) at java.awt.Window.setVisible(Window.java:1014) at breakout.Breakout.(Breakout.java:16) at breakout.Breakout.main(Breakout.java:20) Exception in thread "Timer-0" java.lang.NullPointerException at breakout.Board$ScheduleTask.run(Board.java:95) at java.util.TimerThread.mainLoop(Timer.java:555) at java.util.TimerThread.run(Timer.java:505)
Because im a Newbie I have no idea how to solve that problem. According to that problem I copy and pasted the code of the tutorial to exclude the possibility of mistakes in the code
here is the tutorial with the java code:
http://zetcode.com/tutorials/javagamestutorial/breakout/
I use Netbeans IDE 8.0
would be nice if someone could help me solving this problem :)
Edit:
as asked for ill paste all my code i have until now in here:
Commons.java
package breakout;
public interface Commons {
public static final int WIDTH = 300;
public static final int HEIGHT = 400;
public static final int BOTTOM = 390;
public static final int PADDLE_RIGHT = 250;
public static final int BALL_RIGHT = 280;
}
Sprite.java
package breakout;
import java.awt.Image;
import java.awt.Rectangle;
public class Sprite { //Basis Klasse für alle Objekte
protected int x;
protected int y;
protected int width;
protected int height;
protected Image image;
public void setX(int x){ //Jedes Objekt hat einen X-Wert
this.x = x;
}
public int getX(){
return x;
}
public void setY(int y){ //Jedes Objekt hat einen Y-Wert
this.y = y;
}
public int getY(){
return y;
}
public int getWidth(){ //Jedes Objekt hat eine Weite
return width;
}
public int getHeight(){ //Jedes Objekt hat eine Höhe
return height;
}
Image getImage(){ //Jedes Objekt hat ein Bild zur darstellung
return image;
}
Rectangle getRect(){ //Jedes Objekt wird mit einem Rectangle definiert
return new Rectangle(x,y,
image.getWidth(null), image.getHeight(null));
}
}
Brick.java
package breakout;
import javax.swing.ImageIcon;
public class Brick extends Sprite {
String brickie = "../../images/brickie.png";
boolean destroyed;
public Brick(int x, int y){
this.x = x;
this.y = y;
ImageIcon ii = new ImageIcon(this.getClass().getResource(brickie));
image = ii.getImage();
width = image.getWidth(null);
height = image.getHeight(null);
destroyed = false;
}
public boolean isDestroyed(){
return destroyed;
}
public void setDestroyed(boolean destroyed){
this.destroyed = destroyed;
}
}
Ball.java
package breakout;
import javax.swing.ImageIcon;
public class Ball extends Sprite implements Commons{
private int xdir;
private int ydir;
protected String ball = "../../images/ball.png";
public Ball(){
xdir = 1;
ydir = -1;
ImageIcon ii = new ImageIcon(this.getClass().getResource(ball));
image = ii.getImage();
width = image.getWidth(null);
height = image.getHeight(null);
resetState();
}
public void move(){
x += xdir;
y += ydir;
if(x == 0){
setXDir(1);
}
if(x == BALL_RIGHT){
setXDir(-1);
}
if(y == 0){
setYDir(1);
}
}
public void resetState()
{
x = 230;
y = 355;
}
public void setXDir(int x)
{
xdir = x;
}
public void setYDir(int y)
{
ydir = y;
}
public int getYDir()
{
return ydir;
}
}
Paddle.java
package breakout;
import java.awt.event.KeyEvent;
import javax.swing.ImageIcon;
public class Paddle extends Sprite implements Commons{
String paddle = "../../images/paddle.png";
int dx;
public Paddle(){
ImageIcon ii= new ImageIcon(this.getClass().getResource(paddle));
image = ii.getImage();
width = image.getWidth(null);
height = image.getHeight(null);
resetState();
}
public void move(){
x += dx;
if(x <= 2)
x = 2;
if(x >= Commons.PADDLE_RIGHT)
x = Commons.PADDLE_RIGHT;
}
public void keypressed(KeyEvent e){
int key = e.getKeyCode();
if(key == KeyEvent.VK_LEFT){
dx = -2;
}
if(key == KeyEvent.VK_RIGHT){
dx = 2;
}
}
public void keyReleased(KeyEvent e){
int key = e.getKeyCode();
if(key == KeyEvent.VK_LEFT){
dx = 0;
}
if(key == KeyEvent.VK_RIGHT){
dx = 0;
}
}
public void resetState(){
x = 200;
y = 360;
}
}
Board.java
package breakout;
import java.awt.Color;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Point;
import java.awt.Toolkit;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.util.Timer;
import java.util.TimerTask;
import javax.swing.JPanel;
public class Board extends JPanel implements Commons{
Image ii;
Timer timer;
String message = "Game Over";
Ball ball;
Paddle paddle;
Brick bricks[];
boolean ingame = true;
int timerId;
public Board(){
addKeyListener(new TAdapter());
setFocusable(true);
bricks = new Brick[30];
setDoubleBuffered(true);
timer = new Timer();
timer.scheduleAtFixedRate(new ScheduleTask(), 1000, 10);
}
public void addNotify(){
super.addNotify();
gameInit();
}
public void gameInit(){
ball = new Ball();
paddle = new Paddle();
int k = 0;
for (int i = 0; i < 5; i++) {
for (int j = 0; j < 6; j++) {
bricks[k] = new Brick(j * 40 + 30, i * 10 + 50);
k++;
}
}
}
public void paint(Graphics g){
super.paint(g);
if(ingame) {
g.drawImage(ball.getImage(), ball.getX(), ball.getY(),
ball.getWidth(), ball.getHeight(), this);
g.drawImage(paddle.getImage(), paddle.getX(), paddle.getY(),
paddle.getWidth(), paddle.getHeight(), this);
for (int i = 0; i < 30; i++) {
if (!bricks[i].isDestroyed())
g.drawImage(bricks[i].getImage(), bricks[i].getX(),
bricks[i].getY(), bricks[i].getWidth(),
bricks[i].getHeight(), this);
}
}else{
Font font = new Font("Verdana",Font.BOLD, 18);
FontMetrics metr = this.getFontMetrics(font);
g.setColor(Color.BLACK);
g.setFont(font);
g.drawString(message,
(Commons.WIDTH - metr.stringWidth(message))
/2,Commons.WIDTH /2);
}
Toolkit.getDefaultToolkit().sync();
g.dispose();
}
private class TAdapter extends KeyAdapter{
public void keyReleased(KeyEvent e){
paddle.keyReleased(e);
}
public void keyPressed(KeyEvent e){
paddle.keypressed(e);
}
}
class ScheduleTask extends TimerTask{
public void run(){
ball.move();
paddle.move();
checkCollision();
repaint();
}
}
public void stopGame(){
ingame = false;
timer.cancel();
}
public void checkCollision(){
if (ball.getRect().getMaxY() > Commons.BOTTOM){
stopGame();
}
for(int i = 0, j = 0; i < 30; i++){
if(bricks[i].isDestroyed()){
j++;
}
if(j == 30){
message = "Victory";
stopGame();
}
}
if ((ball.getRect()).intersects(paddle.getRect())) {
int paddleLPos = (int)paddle.getRect().getMinX();
int ballLPos = (int)ball.getRect().getMinX();
int first = paddleLPos + 8;
int second = paddleLPos + 16;
int third = paddleLPos + 24;
int fourth = paddleLPos + 32;
if (ballLPos < first) {
ball.setXDir(-1);
ball.setYDir(-1);
}
if (ballLPos >= first && ballLPos < second) {
ball.setXDir(-1);
ball.setYDir(-1 * ball.getYDir());
}
if (ballLPos >= second && ballLPos < third) {
ball.setXDir(0);
ball.setYDir(-1);
}
if (ballLPos >= third && ballLPos < fourth) {
ball.setXDir(1);
ball.setYDir(-1 * ball.getYDir());
}
if (ballLPos > fourth) {
ball.setXDir(1);
ball.setYDir(-1);
}
}
for (int i = 0; i < 30; i++) {
if ((ball.getRect()).intersects(bricks[i].getRect())) {
int ballLeft = (int)ball.getRect().getMinX();
int ballHeight = (int)ball.getRect().getHeight();
int ballWidth = (int)ball.getRect().getWidth();
int ballTop = (int)ball.getRect().getMinY();
Point pointRight =
new Point(ballLeft + ballWidth + 1, ballTop);
Point pointLeft = new Point(ballLeft - 1, ballTop);
Point pointTop = new Point(ballLeft, ballTop - 1);
Point pointBottom =
new Point(ballLeft, ballTop + ballHeight + 1);
if (!bricks[i].isDestroyed()) {
if (bricks[i].getRect().contains(pointRight)) {
ball.setXDir(-1);
}
else if (bricks[i].getRect().contains(pointLeft)) {
ball.setXDir(1);
}
if (bricks[i].getRect().contains(pointTop)) {
ball.setYDir(1);
}
else if (bricks[i].getRect().contains(pointBottom)) {
ball.setYDir(-1);
}
bricks[i].setDestroyed(true);
}
}
}
}
}
Breakout.java
package breakout;
import javax.swing.JFrame;
public class Breakout extends JFrame {
public Breakout()
{
add(new Board());
setTitle("Breakout");
setDefaultCloseOperation(EXIT_ON_CLOSE);
setSize(Commons.WIDTH, Commons.HEIGHT);
setLocationRelativeTo(null);
setIgnoreRepaint(true);
setResizable(false);
setVisible(true);
}
public static void main(String[] args) {
new Breakout();
}
}
All code should be like in the Tutorial except the paths to the images, i edited on my own
It just that compiler is not able to find ImageIcon source that u have provide for setting image. Do one thing for checking this stuff. have other Image URL and set it to that position. and Run it again.
