Develop Reference

Java Draw not moving snake

I am trying to create a snake clone just as a practice. ive drawn the snake and added the movement patterns but the snake eats on it self when I press any key to move. but its not moving. the array retracts the reactacles on the starting point and does nothing.
here is my snake class I have removed my comments as they where more than the code and the posting system was not allowing me to post
Edit
If you need anything from the other classes please let me know. but I think my error is somewhere in here
EDIT 2
Added the entire code, you can just copy paste in inside a new project and you will reproduce my error.
public class Snake {
List<Point> sPoints;
int xDir,yDir;
boolean isMoving,addTail;
final int sSize = 20, startX = 150 , startY = 150;
public Snake(){
sPoints = new ArrayList<Point>();
xDir = 0;
yDir = 0;
isMoving = false;
addTail = false;
sPoints.add(new Point(startX,startY));
for(int i=1; i<sSize; i++) {
sPoints.add(new Point(startX - i * 4,startY));
}
}
public void draw(Graphics g){
g.setColor(Color.white);
for(Point p : sPoints) {
g.fillRect(p.getX(),p.getY(),4,4);
}
}
public void move(){
if (isMoving) {
Point temp = sPoints.get(0);
Point last = sPoints.get(sPoints.size() - 1);
Point newstart = new Point(temp.getX() + xDir * 4, temp.getY() + yDir * 4);
for (int i = sPoints.size() - 1; i >= 1; i--) {
sPoints.set(i, sPoints.get(i - 1));
}
sPoints.set(0, newstart);
}
}
public int getxDir() {
return xDir;
}
public void setxDir(int x) {
this.xDir = xDir;
}
public int getyDir() {
return yDir;
}
public void setyDir(int y) {
this.yDir = yDir;
}
public int getX(){
return sPoints.get(0).getX();
}
public int getY(){
return sPoints.get(0).getY();
}
public boolean isMoving() {
return isMoving;
}
public void setIsMoving(boolean b) {
isMoving = b;
}
}
The following is the point class. just some getters setters for the points ,for those i used the IntelliJ to auto generate them.. (again i removed comments )
public class Point {
private int x,y;
public Point() {
x = 0;
y = 0;
}
public Point(int x, int y) {
this.x =x;
this.y =y;
}
public void setX(int x) {
this.x = x;
}
public void setY(int y) {
this.y = y;
}
public int getX() {
return x;
}
public int getY() {
return y;
}
}
and finally my main class called game.
in here what I do is create my applet give it background color. create my threat for the runnable. and also add the movement patterns for up/right/down/left...
and use several classes to update my drawing patterns so it can simulate movement by updating each of state of my rect list.
import java.applet.Applet;
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
public class Game extends Applet implements Runnable, KeyListener {
//setting up double buffering.
Graphics graphics;
Image img;
Thread thread;
Snake snake;
public void init() {
//setting the size of our Applet
this.resize(400,400);
//we gonna create the image just the same size as our applet.
img = createImage(400,400);
//this represents our offscreen image that we will draw
graphics = img.getGraphics();
this.addKeyListener(this);
snake = new Snake();
thread = new Thread(this);
thread.start();
}
public void paint(Graphics g) {
//Setting the background of our applet to black
graphics.setColor(Color.black);
//Fill rectangle 0 , 0 (starts from) for top left corner and then 400,400 to fill our entire background to black
graphics.fillRect(0,0,400,400);
snake.draw(graphics);
//painting the entire image
g.drawImage(img,0,0,null);
}
//Update will call on Paint(g)
public void update(Graphics g){
paint(g);
}
//Repaint will call on Paint(g)
public void repaint(Graphics g){
paint(g);
}
public void run() {
//infinite loop
for(;;) {
snake.move();
//drawing snake
this.repaint();
//Creating a time delay
try {
Thread.sleep(40);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public void keyTyped(KeyEvent keyEvent) {
}
public void keyPressed(KeyEvent keyEvent) {
if(!snake.isMoving()){ //this will allow the snake to start moving, but will disable LEFT for just the 1st move
if(keyEvent.getKeyCode() == KeyEvent.VK_UP || keyEvent.getKeyCode() == KeyEvent.VK_RIGHT ||
keyEvent.getKeyCode() == KeyEvent.VK_DOWN ) {
snake.setIsMoving(true);
}
}
//setting up Key mapping so when the user presses UP,RIGHT,DOWN,LEFT. the Snake will move accordingly
if(keyEvent.getKeyCode() == KeyEvent.VK_UP) {
if (snake.getyDir() != 1) {
snake.setyDir(-1);
snake.setxDir(0);
}
}
if(keyEvent.getKeyCode() == KeyEvent.VK_RIGHT) {
if (snake.getxDir() != -1) {
snake.setxDir(1);
snake.setyDir(0);
}
}
if(keyEvent.getKeyCode() == KeyEvent.VK_DOWN) {
if (snake.getyDir() != -1) {
snake.setyDir(1);
snake.setxDir(0);
}
}
if(keyEvent.getKeyCode() == KeyEvent.VK_LEFT) {
if (snake.getxDir() != 1) {
snake.setxDir(-1);
snake.setyDir(0);
}
}
}
public void keyReleased(KeyEvent keyEvent) {
}
}

Here is some opinion I have reading your code.
The reason your snake won't move is because your snake.setyDir() and
snake.setxDir() didn't take the input to overwrite xDir and yDir. They are assigning to itself.
There is a Point2D class ready for you in JDK
When moving the snake, you just need to remove the tail and add one
more block before the head. You can keep the body tight (according
to my common knowledge to snake).
Consider a L shape snake on the left, the bottom end is the head and it is currently heading right. To move the snake, remove the tail (green block) and add one more to the head according to its direction (red block). It final state become the snake on the right. LinkedList suit the needs.
If using two int (xDir and yDir) to control the snake direction
is confusing, you can help your self by creating a enum. Those -1,
0, 1 with x and y may confuse you.
Declare constant instead of magic number. e.g. the width of block 4,
image size 400
Is Snake.addTail unnecessary?
Attribute should has accessibility modifier
End result:
Game.java
import java.applet.Applet;
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.Arrays;
public class Game extends Applet implements Runnable, KeyListener {
private final int GAMEBOARD_WIDTH = 400;
// setting up double buffering.
private Graphics graphics;
private Image img;
private Thread thread;
private Snake snake;
public void init() {
// setting the size of our Applet
this.resize(GAMEBOARD_WIDTH, GAMEBOARD_WIDTH);
// we gonna create the image just the same size as our applet.
img = createImage(GAMEBOARD_WIDTH, GAMEBOARD_WIDTH);
// this represents our offscreen image that we will draw
graphics = img.getGraphics();
this.addKeyListener(this);
snake = new Snake();
thread = new Thread(this);
thread.start();
}
public void paint(Graphics g) {
// Setting the background of our applet to black
graphics.setColor(Color.BLACK);
// Fill rectangle 0 , 0 (starts from) for top left corner and then 400,400 to
// fill our entire background to black
graphics.fillRect(0, 0, GAMEBOARD_WIDTH, GAMEBOARD_WIDTH);
snake.draw(graphics);
// painting the entire image
g.drawImage(img, 0, 0, null);
}
// Update will call on Paint(g)
public void update(Graphics g) {
paint(g);
}
// Repaint will call on Paint(g)
public void repaint(Graphics g) {
paint(g);
}
public void run() {
// infinite loop
for (;;) {
snake.move();
// drawing snake
this.repaint();
// Creating a time delay
try {
Thread.sleep(40);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public void keyTyped(KeyEvent keyEvent) {
}
public void keyPressed(KeyEvent keyEvent) {
int keyCode = keyEvent.getKeyCode();
if (!snake.isMoving()) {
// this will allow the snake to start moving, but will disable LEFT for just the
// 1st move
if (matchKey(keyCode, KeyEvent.VK_UP, KeyEvent.VK_RIGHT, KeyEvent.VK_DOWN)) {
snake.setIsMoving(true);
}
}
// setting up Key mapping so when the user presses UP,RIGHT,DOWN,LEFT. the Snake
// will move accordingly
if (matchKey(keyCode, KeyEvent.VK_UP)) {
snake.setDirection(Direction.UP);
}
if (matchKey(keyCode, KeyEvent.VK_RIGHT)) {
snake.setDirection(Direction.RIGHT);
}
if (matchKey(keyCode, KeyEvent.VK_DOWN)) {
snake.setDirection(Direction.DOWN);
}
if (matchKey(keyCode, KeyEvent.VK_LEFT)) {
snake.setDirection(Direction.LEFT);
}
}
// return true if targetKey contains the provided keyCode
private boolean matchKey(int keyCode, int... targetKey) {
return Arrays.stream(targetKey).anyMatch(i -> i == keyCode);
}
public void keyReleased(KeyEvent keyEvent) {
}
}
Snake.java
import java.awt.Color;
import java.awt.Graphics;
import java.awt.geom.Point2D;
import java.util.LinkedList;
public class Snake {
private final int sSize = 20, startX = 150, startY = 150;
private final int BLOCK_WIDTH = 4;
private LinkedList<Point2D.Float> sPoints;
private boolean isMoving;
private Direction direction;
public Snake() {
sPoints = new LinkedList<Point2D.Float>();
isMoving = false;
sPoints.add(new Point2D.Float(startX, startY));
for (int i = 1; i < sSize; i++) {
sPoints.add(new Point2D.Float(startX - i * BLOCK_WIDTH, startY));
}
}
public void draw(Graphics g) {
g.setColor(Color.white);
for (Point2D p : sPoints) {
g.fillRect((int) p.getX(), (int) p.getY(), BLOCK_WIDTH, BLOCK_WIDTH);
}
}
public void move() {
if (isMoving) {
sPoints.removeLast();
steer(sPoints.getFirst());
}
}
private void steer(Point2D head) {
Point2D.Float newHead = new Point2D.Float();
switch (this.getDirection()) {
case UP:
newHead.setLocation(head.getX(), head.getY() - BLOCK_WIDTH);
break;
case DOWN:
newHead.setLocation(head.getX(), head.getY() + BLOCK_WIDTH);
break;
case LEFT:
newHead.setLocation(head.getX() - BLOCK_WIDTH, head.getY());
break;
case RIGHT:
newHead.setLocation(head.getX() + BLOCK_WIDTH, head.getY());
break;
}
this.sPoints.addFirst(newHead);
}
public int getX() {
return (int) sPoints.get(0).getX();
}
public int getY() {
return (int) sPoints.get(0).getY();
}
public boolean isMoving() {
return isMoving;
}
public void setIsMoving(boolean b) {
isMoving = b;
}
public Direction getDirection() {
return direction;
}
public void setDirection(Direction d) {
if (this.getDirection() == null) {
this.direction = d;
} else if (!this.getDirection().isOpposite(d)) {
this.direction = d;
}
}
}
Direction.java
public enum Direction {
UP(-1), DOWN(1), LEFT(-2), RIGHT(2);
int vector;
Direction(int i) {
this.vector = i;
}
public boolean isOpposite(Direction d) {
return this.vector + d.vector == 0;
}
}

Snack.java
import java.awt.EventQueue;
import javax.swing.JFrame;
public class Snake extends JFrame {
public Snake() {
initUI();
}
private void initUI() {
add(new Board());
setResizable(false);
pack();
setTitle("Snake");
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args) {
EventQueue.invokeLater(() -> {
JFrame ex = new Snake();
ex.setVisible(true);
});
}
}
Board.java
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.ImageIcon;
import javax.swing.JPanel;
import javax.swing.Timer;
public class Board extends JPanel implements ActionListener {
private final int B_WIDTH = 300;
private final int B_HEIGHT = 300;
private final int DOT_SIZE = 10;
private final int ALL_DOTS = 900;
private final int RAND_POS = 29;
private final int DELAY = 140;
private final int x\[\] = new int\[ALL_DOTS\];
private final int y\[\] = new int\[ALL_DOTS\];
private int dots;
private int apple_x;
private int apple_y;
private boolean leftDirection = false;
private boolean rightDirection = true;
private boolean upDirection = false;
private boolean downDirection = false;
private boolean inGame = true;
private Timer timer;
private Image ball;
private Image apple;
private Image head;
public Board() {
initBoard();
}
private void initBoard() {
addKeyListener(new TAdapter());
setBackground(Color.black);
setFocusable(true);
setPreferredSize(new Dimension(B_WIDTH, B_HEIGHT));
loadImages();
initGame();
}
private void loadImages() {
ImageIcon iid = new ImageIcon("src/resources/dot.png");
ball = iid.getImage();
ImageIcon iia = new ImageIcon("src/resources/apple.png");
apple = iia.getImage();
ImageIcon iih = new ImageIcon("src/resources/head.png");
head = iih.getImage();
}
private void initGame() {
dots = 3;
for (int z = 0; z < dots; z++) {
x\[z\] = 50 - z * 10;
y\[z\] = 50;
}
locateApple();
timer = new Timer(DELAY, this);
timer.start();
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
doDrawing(g);
}
private void doDrawing(Graphics g) {
if (inGame) {
g.drawImage(apple, apple_x, apple_y, this);
for (int z = 0; z < dots; z++) {
if (z == 0) {
g.drawImage(head, x\[z\], y\[z\], this);
} else {
g.drawImage(ball, x\[z\], y\[z\], this);
}
}
Toolkit.getDefaultToolkit().sync();
} else {
gameOver(g);
}
}
private void gameOver(Graphics g) {
String msg = "Game Over";
Font small = new Font("Helvetica", Font.BOLD, 14);
FontMetrics metr = getFontMetrics(small);
g.setColor(Color.white);
g.setFont(small);
g.drawString(msg, (B_WIDTH - metr.stringWidth(msg)) / 2, B_HEIGHT / 2);
}
private void checkApple() {
if ((x\[0\] == apple_x) && (y\[0\] == apple_y)) {
dots++;
locateApple();
}
}
private void move() {
for (int z = dots; z > 0; z--) {
x\[z\] = x\[(z - 1)\];
y\[z\] = y\[(z - 1)\];
}
if (leftDirection) {
x\[0\] -= DOT_SIZE;
}
if (rightDirection) {
x\[0\] += DOT_SIZE;
}
if (upDirection) {
y\[0\] -= DOT_SIZE;
}
if (downDirection) {
y\[0\] += DOT_SIZE;
}
}
private void checkCollision() {
for (int z = dots; z > 0; z--) {
if ((z > 4) && (x\[0\] == x\[z\]) && (y\[0\] == y\[z\])) {
inGame = false;
}
}
if (y\[0\] >= B_HEIGHT) {
inGame = false;
}
if (y\[0\] < 0) {
inGame = false;
}
if (x\[0\] >= B_WIDTH) {
inGame = false;
}
if (x\[0\] < 0) {
inGame = false;
}
if (!inGame) {
timer.stop();
}
}
private void locateApple() {
int r = (int) (Math.random() * RAND_POS);
apple_x = ((r * DOT_SIZE));
r = (int) (Math.random() * RAND_POS);
apple_y = ((r * DOT_SIZE));
}
#Override
public void actionPerformed(ActionEvent e) {
if (inGame) {
checkApple();
checkCollision();
move();
}
repaint();
}
private class TAdapter extends KeyAdapter {
#Override
public void keyPressed(KeyEvent e) {
int key = e.getKeyCode();
if ((key == KeyEvent.VK_LEFT) && (!rightDirection)) {
leftDirection = true;
upDirection = false;
downDirection = false;
}
if ((key == KeyEvent.VK_RIGHT) && (!leftDirection)) {
rightDirection = true;
upDirection = false;
downDirection = false;
}
if ((key == KeyEvent.VK_UP) && (!downDirection)) {
upDirection = true;
rightDirection = false;
leftDirection = false;
}
if ((key == KeyEvent.VK_DOWN) && (!upDirection)) {
downDirection = true;
rightDirection = false;
leftDirection = false;
}
}
}
}

Implementing extended class or not

Another question about inheritance in java: I was wondering about two things:
1) how can I set my program to switch between using an inherited class or not?
2) I'm not sure why my extended class glidingObject.java is not responding to my key presses
Here's my Game.java (which runs the game; I should be passing in some parameter that allows the user to choose which class to use right - either flying object or gliding object? I've also included my two classes for flying object and gliding object)
public class Game extends JPanel {
private static final long serialVersionUID = 1L;
public static int WIDTH = 800, HEIGHT = 750;
public static ArrayList<Rectangle> columns;
public static Random rand;
public static double score;
public static boolean gameOver, started; //two modes, started and gameover
public static String username;
public static String currTime;
public static Timer timer;
public static flyingObject obj;
private PropertyChangeSupport mPcs = new PropertyChangeSupport(this);
public Game(flyingObject object){
obj = object;
timer = new Timer(20, new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
tick();
} catch (IOException e1) {
e1.printStackTrace();
}
}
});
columns = new ArrayList<Rectangle>();
rand = new Random();
Background bk = new Background();
addColumn(true);
addColumn(true);
addColumn(true);
addColumn(true);
addMouseListener(new MouseAdapter() {
#Override
public void mouseReleased(MouseEvent e) {
started = true;
}
});
PropertyChangeListener listener = new PropertyChangeListener() {
#Override
public void propertyChange(PropertyChangeEvent evt) {
try {
scoreBoard.record();
} catch (IOException e) {
e.printStackTrace();
}
}
};
this.addPropertyChangeListener(listener);
getDate(); //get the date of the game played
mPcs.firePropertyChange("gameOver",false, true); //alert record() method when the game is over
timer.start();
}
//adding the column
public static void addColumn(boolean start) {
int space = 300;
int width = 100;
int height = 50 + rand.nextInt(300);
if (start) {
//add top and bottom
columns.add(new Rectangle(WIDTH + width + columns.size() * 300, HEIGHT - height - 120, width, height + 100));
columns.add(new Rectangle(WIDTH + width + (columns.size() - 1) * 300, 0, width, HEIGHT - height - space));
}
else
{
columns.add(new Rectangle(columns.get(columns.size() - 1).x + 600, HEIGHT - height - 120, width, height + 100));
columns.add(new Rectangle(columns.get(columns.size() - 1).x, 0, width, HEIGHT - height - space));
}
}
//paint the columns
public void paintColumn(Graphics g, Rectangle column) {
g.setColor(Color.white);
g.fillRect(column.x, column.y, column.width, column.height);
}
public static void reset() {
obj = new glidingObject(WIDTH / 2 - 10, HEIGHT / 2 - 10);
columns.clear();
score = 0.0;
addColumn(true);
addColumn(true);
addColumn(true);
addColumn(true);
gameOver = false;
}
public void tick() throws IOException {
if (started) {
int speed = 10;
glidingObject.move();
for (int i = 0; i < columns.size(); i ++) {
Rectangle column = columns.get(i);
column.x -= speed;
if (column.x + column.width < 0) {
columns.remove(column);
if (column.y == 0) {
addColumn(false);
}
}
}
for (Rectangle column: columns) {
if (column.x == glidingObject.X) {
score += 0.5;
}
if (column.intersects(glidingObject.getBounds())) {
gameOver = true;
//when the object crashes, it does not go through the column
if (glidingObject.X <= column.x) {
glidingObject.X = column.x - glidingObject.DIAMETER;
}
else if (glidingObject.Y < column.height) {
glidingObject.Y = column.height;
}
Main.gameOver();
}
}
if (glidingObject.Y > HEIGHT || glidingObject.Y < 0) {
gameOver = true;
//timer.stop();
Main.gameOver();
}
if (glidingObject.Y + glidingObject.YMotion >= HEIGHT) {
gameOver = true;
//timer.stop();
Main.gameOver();
}
}
//update the display
repaint();
}
public void getDate() {
DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Date date = new Date();
currTime = dateFormat.format(date);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Background.paint(g);
glidingObject.paint(g);
for (Rectangle column: columns) {
paintColumn(g, column);
}
g.setColor(Color.white);
g.setFont(new Font("Manaspace", 1, 60));
if (!started) {
g.drawString("Click to start!", 75, HEIGHT / 2 - 50);
}
if (gameOver) {
g.drawString("Game Over!", 200, HEIGHT / 2 - 50);
}
if (!gameOver && started) {
g.drawString(String.valueOf(score), WIDTH / 2 - 25, 100);
}
}
}
class flyingobject.java
public class flyingObject implements ActionListener, MouseListener, KeyListener {
static int DIAMETER = 25;
static int Y; // Y position of the unicorn
static int X; // X position of the unicorn
static int YMotion; // Y movement of the unicorn
//parameters are the initial positions
public flyingObject(int xpos, int ypos) {
X = xpos;
Y = ypos; // this changes
}
//getters
public int getX() {
return X;
}
public int getY() {
return Y;
}
//setters
public void setX(int newX) {
X = newX;
}
public void setY(int newY) {
Y = newY;
}
//the bounds of the object (rectangle)
public static Rectangle getBounds() {
return new Rectangle(X, Y, DIAMETER, DIAMETER);
}
//the visible component of the object - this can get overriden by subclasses
public static void paint(Graphics g){
g.setColor(Color.white);
g.fillRect(X, Y, DIAMETER, DIAMETER);
}
//the movement component of the object
public static void jump() {
if (Game.gameOver) {
Game.reset();
Game.gameOver = false;
}
if (!Game.started) {
Game.started = true;
}
else if (!Game.gameOver) {
if (YMotion > 0) {
YMotion = 0;
}
YMotion -= 14;
}
}
public static void move() {
if ((Y > 0) && (Y < Game.HEIGHT)) {
YMotion += 1.5; // gravity
Y += YMotion;
}
}
#Override
public void keyTyped(KeyEvent e) {
}
#Override
public void keyPressed(KeyEvent e) {
}
#Override
public void keyReleased(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_SPACE)
{
jump();
}
}
#Override
public void mouseClicked(MouseEvent e) {
jump();
}
#Override
public void mousePressed(MouseEvent e) {
}
#Override
public void mouseReleased(MouseEvent e) {
}
#Override
public void mouseEntered(MouseEvent e) {
}
#Override
public void mouseExited(MouseEvent e) {
}
#Override
public void actionPerformed(ActionEvent e) {
}
}
Class glidingobject.java (the game.java should allow the user to choose between just using flying object, or the extended class gliding object)
public class glidingObject extends flyingObject{
//velocity of the object
private static int vx;
private static int vy;
private static int lives;
public glidingObject(int xpos, int ypos) {
super(xpos, ypos);
vx = 0;
vy = 0;
lives = 3;
}
//getter methods
public int getVx() {
return vx;
}
public int getVy() {
return vy;
}
//setter methods
public void setVx(int newVx) {
vx = newVx;
}
public void setVy(int newVy) {
vy = newVy;
}
//moves the object
public static void jump() {
X += vx;
Y += vy;
}
public static void paint(Graphics g) {
g.setColor(Color.CYAN);
g.fillOval(X, Y, DIAMETER, DIAMETER);
}
#Override
public void keyTyped(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_RIGHT){
vx = 10;
}
if (e.getKeyCode() == KeyEvent.VK_LEFT){
vx = -10;
}
if (e.getKeyCode() == KeyEvent.VK_UP){
vy = 10;
}
if (e.getKeyCode() == KeyEvent.VK_DOWN){
vy = -10;
}
}
#Override
public void keyPressed(KeyEvent e) {
}
#Override
public void keyReleased(KeyEvent e) {
}
#Override
public void mouseClicked(MouseEvent e) {
}
#Override
public void mousePressed(MouseEvent e) {
}
#Override
public void mouseReleased(MouseEvent e) {
}
#Override
public void mouseEntered(MouseEvent e) {
}
#Override
public void mouseExited(MouseEvent e) {
}
#Override
public void actionPerformed(ActionEvent e) {
}
}

I should be passing in some parameter that allows the user to choose which class to use right - either flying object or gliding object?
This is where interfaces become so powerful. Both the "flying" and "gliding" objects are going to share some common properties/functionality, these should be described by the interface. You Game should then only accept instances of this interface, it shouldn't care what the implementation, only that they adhere to the agreed interface.
This is principle of "code to interface, not implementation"
How complicated this gets is up to you, for example, you could have abstract implementations which describe "air" based entities and "ground" based entities, from which you could have "powered" and "unpowered" implementations of the abstract "air" class, all of which would be tied back to the "game entity" interface
I'm not sure why my extended class glidingObject.java is not responding to my key presses
This is because you're using KeyListener, this well known for it's focus related issues. See How to Use Key Bindings for the recommended solution

Background image in different place every time

I have a large program that I will post some classes of and hopefully you guys can find the problem. Basically, sometimes when I start it, it creates the game just fine, and others the background is up a few pixels to the north and west directions leaving very unsightly whitespace. I cannot seem to find the missing piece of code that decides whether not it does this. It honestly feel like some kind of rendering glitch on my machine. At any rate, I have put a background getX and getY method in for debugging and have noticed that whether the background is fully stretched to the screen(its a custom background so the pixel height and width match perfectly), or its up and to the left, the background still reads that it is displaying at (0,0). I will post all the methods from the main thread to the creating of the background in the menu. I will leave notes indicating the path it takes through this code that gets it to creating the background. Thank you for your help and I will check in regularly for edits and more information.
EDIT: added background.java
EDIT2: added pictures explaining problem
Menu.java *ignore the FileIO code, the main point is the creation of a new GamePanel()
public class Menu {
private static File file;
public static void main(String[] args) throws IOException {
file = new File("saves.txt");
if(file.exists()){
FileIO.run();
FileIO.profileChoose();
}
else{
FileIO.profileCreate();
FileIO.run();
}
JFrame window = new JFrame("Jolly Jackpot Land");
window.setContentPane(new GamePanel());
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setResizable(false);
window.pack();
window.setLocationRelativeTo(null);
window.setVisible(true);
}
}
Next is the GamePanel.java
public class GamePanel extends JPanel implements Runnable, KeyListener {
// ID
private static final long serialVersionUID = 1L;
// Dimensions
public static final int WIDTH = 320;
public static final int HEIGHT = 240;
public static final int SCALE = 2;
// Thread
private Thread thread;
private boolean running;
private int FPS = 30;
private long targetTime = 1000 / FPS;
// Image
private BufferedImage image;
private Graphics2D g;
// Game State Manager
private GameStateManager gsm;
public GamePanel() {
super();
setPreferredSize(new Dimension(WIDTH * SCALE, HEIGHT * SCALE));
setFocusable(true);
requestFocus();
}
public void addNotify() {
super.addNotify();
if (thread == null) {
thread = new Thread(this);
addKeyListener(this);
thread.start();
}
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
}
private void init() {
image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
g = (Graphics2D) image.getGraphics();
running = true;
gsm = new GameStateManager();
}
#Override
public void run() {
init();
long start;
long elapsed;
long wait;
// Game Loop
while (running) {
start = System.nanoTime();
update();
draw();
drawToScreen();
elapsed = System.nanoTime() - start;
wait = targetTime - (elapsed / 1000000);
if (wait < 0) {
wait = 5;
}
try {
Thread.sleep(wait);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
private void update() {
gsm.update();
}
private void draw() {
gsm.draw(g);
}
private void drawToScreen() {
Graphics g2 = getGraphics();
g2.drawImage(image, 0, 0, WIDTH * SCALE, HEIGHT * SCALE, null);
g2.dispose();
}
#Override
public void keyPressed(KeyEvent k) {
gsm.keyPressed(k.getKeyCode());
}
#Override
public void keyReleased(KeyEvent k) {
}
#Override
public void keyTyped(KeyEvent arg0) {
}
}
This calls for the creation of a new GameStateManager object in its init() method and the class for that is here.
GameStateManager.java
public class GameStateManager {
private ArrayList<GameState> gameStates;
private int currentState;
public static final int MENUSTATE = 0;
public static final int SLOTGAMESTATE = 1;
public static final int DICEGAMESTATE = 2;
public static final int ROULETTEGAMESTATE = 3;
public static final int LEADERBOARDSTATE = 4;
public static final int SETTINGSSTATE = 5;
public static final int HELPSTATE = 6;
public GameStateManager() {
gameStates = new ArrayList<GameState>();
currentState = 0;
gameStates.add(new MenuState(this));
gameStates.add(new SlotGameState(this));
gameStates.add(new DiceGameState(this));
gameStates.add(new RouletteGameState(this));
gameStates.add(new LeaderboardState(this));
gameStates.add(new SettingsState(this));
gameStates.add(new HelpState(this));
}
public void setState(int state){
currentState = state;
gameStates.get(currentState).init();
currentState = 0;
}
public int getState() {
return currentState;
}
public void update() {
gameStates.get(currentState).init();
}
public void draw(java.awt.Graphics2D g){
gameStates.get(currentState).draw(g);
}
public void keyPressed(int k){
gameStates.get(currentState).keyPressed(k);
}
public void keyReleased(int k) {
gameStates.get(currentState).keyReleased(k);
}
}
GameState is an abstract class I have so its not worth posting, it only contains init(), draw(), etc. This next class is the last and final class and is called because GameStateMananger starts at MENUSTATE or 0, and when GSM is initialized it initializes its current state, thus taking us to the class MenuState
MenuState.java
public class MenuState extends GameState {
private Background bg;
public FontMetrics fontMetrics;
private int choice = 0;
private String[] options = { "Slot Machine", "Dice Toss", "Roulette Wheel", "Leaderboards", "Settings", "Help",
"Quit" };
private Color titleColor;
private Font titleFont;
private Font font;
public MenuState(GameStateManager gsm) {
this.gsm = gsm;
try {
bg = new Background("/Backgrounds/happybg.png");
titleColor = Color.WHITE;
titleFont = new Font("Georgia", Font.PLAIN, 28);
} catch (Exception e) {
e.printStackTrace();
}
font = new Font("Arial", Font.PLAIN, 12);
}
#Override
public void init() {
}
#Override
public void update() {
}
#Override
public void draw(Graphics2D g) {
Canvas c = new Canvas();
fontMetrics = c.getFontMetrics(font);
// Draw BG
bg.draw(g);
// Draw title
g.setColor(titleColor);
g.setFont(titleFont);
String title = "Jolly Jackpot Land!";
g.drawString(title, 36, 60);
g.setFont(font);
for (int i = 0; i < options.length; i++) {
if (i == choice)
g.setColor(Color.RED);
else
g.setColor(Color.WHITE);
g.drawString(options[i], 30, 120 + i * 15);
}
g.setColor(Color.WHITE);
g.setFont(new Font("Arial", Font.PLAIN, 10));
g.drawString("v1.1", 165, 235);
Object[] a = { ("Name: " + Player.getName()), ("Gil: " + Player.getGil()),
("Personal Best: " + Player.getPersonalBest()), ("Winnings: " + Player.getWinnings()),
("Wins: " + Player.getWins()), ("Losses: " + Player.getLosses()),
("Win/Loss Ratio: " + String.format("%.2f", Player.getRatio()) + "%") };
g.setFont(font);
if (Player.getName() != null) {
for (int x = 0; x < a.length; x++) {
g.drawString(a[x].toString(), GamePanel.WIDTH - fontMetrics.stringWidth(a[x].toString()) - 30,
120 + x * 15);
}
}
}
private void select() {
if (choice == 0) {
// Slots
gsm.setState(GameStateManager.SLOTGAMESTATE);
}
if (choice == 1) {
// Dice
gsm.setState(GameStateManager.DICEGAMESTATE);
}
if (choice == 2) {
// Roulette
gsm.setState(GameStateManager.ROULETTEGAMESTATE);
}
if (choice == 3) {
// Leaderboards
gsm.setState(GameStateManager.LEADERBOARDSTATE);
}
if (choice == 4) {
// Settings
gsm.setState(GameStateManager.SETTINGSSTATE);
}
if (choice == 5) {
// Help
gsm.setState(GameStateManager.HELPSTATE);
}
if (choice == 6) {
// Quit
System.exit(0);
}
}
#Override
public void keyPressed(int k) {
if (k == KeyEvent.VK_ENTER) {
select();
}
if (k == KeyEvent.VK_UP) {
choice--;
if (choice == -1) {
choice = options.length - 1;
}
}
if (k == KeyEvent.VK_DOWN) {
choice++;
if (choice == options.length) {
choice = 0;
}
}
}
#Override
public void keyReleased(int k) {
}
}
Background.java
public class Background {
private BufferedImage image;
private double x;
private double y;
public Background(String s) {
try {
image = ImageIO.read(getClass().getResourceAsStream(s));
} catch (Exception e) {
e.printStackTrace();
}
}
public void setPosition(double x, double y) {
this.setX(x);
this.setY(y);
}
public void draw(Graphics2D g) {
g.drawImage(image, 0, 0, null);
}
public double getX() {
return x;
}
public void setX(double x) {
this.x = x;
}
public double getY() {
return y;
}
public void setY(double y) {
this.y = y;
}
}
This is where it waits for input in the game loop basically. I know this is a lot of code, but a lot of it is skimming till a method call takes you to the next class. I just can't figure out why it only happens sometimes, if it was consistent I could debug it. Any help would be extremely appreciated.
These are both from clicking the .jar of the above program, exact same .jar, exact same source code, different result. I am bewildered.

Creating multiple instances of an object. (Game)

I've been asked to make a game for my CS (high school) class as my end of semester assignment. We haven't been taught properly all of the coding required to make a game so my knowledge in this area is very poor. Anyways, the game I am trying to make is something like "Flappy Fall" (an Apple appstore game) where objects fall from the top of the screen and descend to the bottom of the screen. The objective is to catch these objects before they reach the bottom. I am able to get one object to fall and have also created the "catcher", but I am not sure how to create multiple falling objects, nor do I know how to remove the object once it has been caught by the catcher. So far I have classes "JavaGame", "Catcher", and "Ball". Any help would be greatly appreciated.
int x, y;
int t = 1;
private Image dbImage;
private Graphics dbGraphics;
Image player;
Image bkg;
static Catcher p = new Catcher(150, 450);
public JavaGame() {
//Game Images
ImageIcon b = new ImageIcon("bkg.png");
bkg = b.getImage();
//Game properties
setTitle("Game");
setSize(350, 600);
setResizable(false);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
addKeyListener(new Keys());
addMouseMotionListener(new Mouse());
}
public void paint(Graphics g) {
//
dbImage = createImage(getWidth(), getHeight());
dbGraphics = dbImage.getGraphics();
draw(dbGraphics);
g.drawImage(dbImage, 0, 0, this);
}
public void draw(Graphics g) {
g.drawImage(bkg, 0, 0, this); //Creates background
p.draw(g);
//while (t < 100) {
p.b.draw(g);
//t++;
//}
g.setColor(Color.WHITE);
g.drawString(""+p.score, 175, 50);
repaint();
}
public static void main(String[] args) {
JavaGame jg = new JavaGame();
//Threads
Thread p1 = new Thread(p);
p1.start();
Thread ball = new Thread(p.b);
ball.start();
}
public class Keys extends KeyAdapter {
public void keyPressed(KeyEvent e) {
p.keyPressed(e);
}
public void keyReleased(KeyEvent e) {
p.keyReleased(e);
}
}
public class Mouse implements MouseMotionListener {
public void mouseDragged(MouseEvent e) {
p.mouseDragged(e);
}
public void mouseMoved(MouseEvent e) {
p.mouseMoved(e);
}
}
}
int x, y, ranX, xDirection;
int score;
Rectangle catch1;
Ball b = new Ball(170, 1);
public Catcher (int x, int y) {
score = 0;
this.x = x;
this.y = y;
catch1 = new Rectangle(this.x, this.y, 50, 15);
}
public void run() {
try {
while(true) {
move();
Thread.sleep(5);
}
}
catch(Exception e) {
System.out.println("Error");
}
}
public void collision() {
if (b.ball.intersects(catch1)) {
b.ball(Color.blue);
score++;
System.out.println(score);
}
}
public void move() {
collision();
catch1.x += xDirection;
if (catch1.x <= 0)
catch1.x = 0;
if (catch1.x >= 300)
catch1.x = 300;
}
public void setXDirection(int xDir) {
xDirection = xDir;
}
public void keyPressed(KeyEvent m) {
int keyCode = m.getKeyCode();
if (keyCode == m.VK_LEFT) {
setXDirection(-1);
}
if (keyCode == m.VK_RIGHT) {
setXDirection(+1);
}
m.consume();
}
public void keyReleased(KeyEvent m) {
int keyCode = m.getKeyCode();
if (keyCode == m.VK_LEFT) {
setXDirection(0);
}
if (keyCode == m.VK_RIGHT) {
setXDirection(0);
}
m.consume();
}
public void mouseDragged(MouseEvent e) {
catch1.x = e.getX()-25;
e.consume();
}
public void mouseMoved(MouseEvent e) {
catch1.x = e.getX()-25;
e.consume();
}
public void draw(Graphics g) {
g.fillRect(catch1.x, catch1.y, catch1.width, catch1.height);
}
}
int x, y, yDirection;
Rectangle ball;
public Ball (int x, int y) {
this.x = x;
this.y = y;
ball = new Rectangle(this.x, this.y, 10, 10);
}
public void run() {
try{
while(true) {
move();
Thread.sleep(5);
}
}
catch(Exception e) {
System.out.println("Error");
}
}
public void move() {
if (ball.y >= 600) {
ball.y = 600;
}
if (ball.y > 0) {
ball.y++;
}
}
public void setYDirection(int yDir) {
yDirection = yDir;
}
public void draw(Graphics g) {
g.setColor(Color.WHITE);
g.fillRect(ball.x, ball.y, ball.width, ball.height);
System.out.println(ball.x+ " "+ ball.y+ " " + ball.width + " " + ball.height);
}
}

I'd re-organize the code a little. In the main game, you can have a collection of 'Ball' types. I'll leave the collection option up to you. But you'll want to add 'new' Balls to the collection and then remove them once they are caught.

Since I do not want to do your assignment, I am just giving a short answer:
By calling new Ball() multiple times.
Of course you might want to add them to a collection, like
List list = new ArrayList();
list.add(ball);
And remove them from that collection once they are finished.

Changing image immediately

I am currently trying to learn a little bit about programming games.
I got myself a player class extending a sprite class i wrote by myself.
Now i want to know, how i can change the image of my player object in the middle of the running game. imagine a spaceship, when pressing the right arrow key it should be a different image, inclined to the right.
now i am trying to do this:
when a button is pressed (e.g. space) setImage(the new image)
But now, when i call this method my image just disappears and the new one won't appear?
Any ideas?
My code of the Main class:
public class Game extends JPanel implements Runnable{
private static final long serialVersionUID = 1L;
public boolean isRunning;
public static final int WIDTH = 320;
public static final int HEIGHT = 240;
public static final int SCALE = 2;
private Player player;
public Game() {
addKeyListener(new TAdapter());
setFocusable(true);
requestFocus();
start();
}
public void start() {
isRunning = true;
new Thread(this).start();
}
public void stop() {
isRunning = false;
}
public void run() {
init();
while(isRunning) {
update();
repaint();
try {
Thread.sleep(5);
} catch (Exception e) {
e.printStackTrace();
}
}
}
public void init() {
player = new Player("/ship_blue", WIDTH - 32/2, 400);
}
public void update() {
player.update();
}
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2d = (Graphics2D)g;
drawPlayer(g2d);
}
public void drawPlayer(Graphics2D g2d) {
if(player.isVisible)g2d.drawImage(player.getImage(),(int) player.getX(), (int) player.getY(), null);
}
public static void main(String[] args) {
Game gameComponent = new Game();
Dimension size = new Dimension(WIDTH*SCALE, HEIGHT*SCALE);
JFrame frame = new JFrame("Invaders");
frame.setVisible(true);
frame.setSize(size);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setResizable(false);
frame.add(gameComponent);
}
public class TAdapter extends KeyAdapter{
public void keyPressed(KeyEvent e) {
player.keyPressed(e);
}
public void keyReleased(KeyEvent e) {
player.keyReleased(e);
}
}
}
That's the main class, now the player class in which i am trying to change the image in the onPress() method:
public class Player extends Sprite{
private double glideSpeed = .125;
private int fixY;
private int xDirection = 0;
private int yDirection = 1;
public Player(String source, int x, int y) {
this.x = x;
this.y = y;
ImageIcon ii = new ImageIcon(this.getClass().getResource(source));
setImage(ii.getImage());
setTileSize(ii.getIconWidth());
setSpeed(0.2);
fixY = y;
}
public void update() {
x += xDirection * 1.4;
glide(10);
}
public void keyPressed(KeyEvent e) {
int key = e.getKeyCode();
if(key == KeyEvent.VK_RIGHT) {
xDirection = 1;
}
if(key == KeyEvent.VK_LEFT) {
xDirection = -1;
}
if(key == KeyEvent.VK_SPACE) {
ImageIcon ii2 = new ImageIcon("/player_blue_negativ");
setImage(ii2.getImage()); //<-----Here I am trying to change the image
}
}
public void keyReleased(KeyEvent e) {
int key = e.getKeyCode();
if(key == KeyEvent.VK_RIGHT || key == KeyEvent.VK_LEFT) {
xDirection = 0;
}
}
public void glide(int span) {
y += yDirection * glideSpeed;
if(y - fixY > span || fixY - y > span) {
yDirection = -yDirection;
}
}
}
And to complete everything here's my sprite class:
public class Sprite {
protected double x;
protected double y;
protected int tileSize;
protected double speed;
protected Image img;
protected boolean isVisible;
public Sprite() {
isVisible = true;
}
public double getSpeed() {
return speed;
}
public double getX() {
return x;
}
public double getY() {
return y;
}
public int getTileSize() {
return tileSize;
}
public Image getImage() {
return img;
}
public boolean getVisible() {
return isVisible;
}
public void setSpeed(double speed) {
this.speed = speed;
}
public void setX(double x) {
this.x = x;
}
public void setY(double y) {
this.y = y;
}
public void setTileSize(int tileSize) {
this.tileSize = tileSize;
}
public void setImage(Image img) {
this.img = img;
}
public void die() {
isVisible = false;
}
}

if(key == KeyEvent.VK_SPACE) {
ImageIcon ii2 = new ImageIcon("/player_blue_negativ");
There is the basic problem. All images should be loaded and cached prior to an event happening. When the event occurs, use the cached image and the GUI should render immediately.
As mentioned by #camickr, the use of an ImageIcon also subtly slips from an URL to a String (presumed to represent a
File path). Stick with the URL obtained from getResource(..).
On ImageObserver.
If an ImageObserver is used to paint the image, the observer will be informed of updates to images that are asynchronously loaded. All components (e.g. JPanel) implement ImageObserver, so..
g2d.drawImage(player.getImage(),(int) player.getX(), (int) player.getY(), null);
Should be:
g2d.drawImage(player.getImage(),(int) player.getX(), (int) player.getY(), this);
Free the EDT!
class Game extends JPanel implements Runnable ..
Thread.sleep(5);
Don't block the EDT (Event Dispatch Thread) - the GUI will 'freeze' when that happens.
Also don't attempt to update the GUI from anything other than the EDT.
Instead of calling Thread.sleep(n) in a Runnable, implement a Swing Timer for repeating tasks or a SwingWorker for long running tasks. See Concurrency in Swing for more details.
Use paintComponent(Graphics) for Swing components!
public void paint(Graphics g) {
Should be:
#Override
public void paintComponent(Graphics g) {

When you load the initial image you use the following without a problem:
ImageIcon ii = new ImageIcon(this.getClass().getResource(source));
When you change the image you use:
ImageIcon ii2 = new ImageIcon("/player_blue_negativ");
I'm guessing you don't find the image, probably because you don't need the "/". But why not use the same method that you know works?