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Issue with my code for moving an image

Hi I am new to making games, and I am working on one for a project. My code however does not make the Ship image move. Can someone help with a reasonable and simple explanation? Maybe even explain how to do this a bit simpler?
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import javax.swing.*;
import java.awt.geom.*;
import java.util.Random;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
public class SpaceJam extends JPanel implements ActionListener
{
private Timer time;
private ImageIcon Ship = new ImageIcon("Spaceship.PNG");
private ImageIcon Back = new ImageIcon("background.PNG");
private ImageIcon Test = new ImageIcon("test.PNG");
private int x, y, dx, dy;
private Image CurrentImage = Ship.getImage();
public SpaceJam()
{
addKeyListener(new AL());
setFocusable(true);
x = 100;
y = 100;
dx = 0;
dy = 0;
time = new Timer(100, this);
time.start();
}
public void actionPerformed(ActionEvent e)
{
repaint();
move();
}
public void paint(Graphics g)
{
super.paint(g);
Graphics2D g2d = (Graphics2D) g;
g2d.drawImage(Back.getImage() ,0,0,null);
g2d.drawImage(CurrentImage, x, y, null);
}
public void move()
{
x += dx;
y += dy;
}
public class AL extends KeyAdapter
{
public void keyPressed(KeyEvent e){
int key = e.getKeyCode();
if(key == KeyEvent.VK_RIGHT)
{
dx = 5;
move();
}
if (key == KeyEvent.VK_LEFT)
{
dx = -5;
move();
}
}
}
}

How to make sprite jump in java?

I have KeyEvents for a sprite for moving left, right, up and down. I was just messing around and was thinking ahead for another project in which I want the sprite to jump. It doesn't have to be fully realistic as I am just beginning. What I have is when the space bar is pressed, it will cause the sprite to jump, lets say "dy = -3". So then I have the KeyEvent for keyReleased, it will fall, "dy = -2". This does not work as the sprite just continues to fall...can someone shine some light?
Entire code:
package collision;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.event.KeyEvent;
import java.util.ArrayList;
import javax.swing.ImageIcon;
public class Craft {
private String craft = "pelican.png";
private int dx;
private int dy;
private int x;
private int y;
private int width;
private int height;
private boolean visible;
private Image image;
private ArrayList missiles;
public Craft() {
ImageIcon ii = new ImageIcon(this.getClass().getResource(craft));
image = ii.getImage();
width = image.getWidth(null);
height = image.getHeight(null);
missiles = new ArrayList();
visible = true;
x = 100;
y = 300;
}
public void move() {
x += dx;
y += dy;
if (x < 1) {
x = 1;
}
if (y < 1) {
y = 1;
}
}
public int getX() {
return x;
}
public int getY() {
return y;
}
public Image getImage() {
return image;
}
public ArrayList getMissiles() {
return missiles;
}
public void setVisible(boolean visible) {
this.visible = visible;
}
public boolean isVisible() {
return visible;
}
public Rectangle getBounds() {
return new Rectangle(x, y, width, height);
}
public void keyPressed(KeyEvent e) {
int key = e.getKeyCode();
if (key == KeyEvent.VK_SPACE) {
}
if (key == KeyEvent.VK_V){
dx = 6;
}
if (key == KeyEvent.VK_LEFT) {
dx = -1;
}
if (key == KeyEvent.VK_RIGHT) {
dx = 2;
}
if (key == KeyEvent.VK_UP) {
dy = -1;
}
if (key == KeyEvent.VK_DOWN) {
dy = 1;
}
}
public void fire() {
missiles.add(new Missile(x + width, y + height/2));
}
public void keyReleased(KeyEvent e) {
int key = e.getKeyCode();
if (key == KeyEvent.VK_LEFT) {
dx = 0;
}
if (key == KeyEvent.VK_SPACE) {
}
if (key == KeyEvent.VK_RIGHT) {
dx = 0;
}
if (key == KeyEvent.VK_UP) {
dy = 0;
}
if (key == KeyEvent.VK_DOWN) {
dy = 0;
}
}
}
As you may have noticed Im new to Java as well as game programming. All I want is the sprite to go up, then come back down. It will always remain stationary if that helps. The sprite just keeps jumping until he is hit by an on coming obstacle. I know there is code for other movements, but those will be removed once I start on next sprite.

This is basic concept. Your implementation will change depending on the implementation of your engine.
The basic idea is the player has a vertical delta which is changed over time by gravity. This effects the sprites vertical speed.
This implementation also has a re-bound delta, which allows the sprite to re-bound rather the "stopping" suddenly. The re-bound is effected by a re-bound degradation, which reduces the amount of re-bound on each re-bound.
This simulates a game character, so you'll need to hit Space to start it bouncing...
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class JumpingSprite {
public static void main(String[] args) {
new JumpingSprite();
}
public JumpingSprite() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public static class TestPane extends JPanel {
protected static final int SPRITE_HEIGHT = 10;
protected static final int SPRITE_WIDTH = 10;
private float vDelta; // The vertical detla...
private float rbDelta; // Rebound delta...
private float rbDegDelta; // The amount the rebound is degradation...
private int yPos; // The vertical position...
private float gDelta; // Gravity, how much the vDelta will be reduced by over time...
private Timer engine;
private boolean bounce = false;
public TestPane() {
yPos = getPreferredSize().height - SPRITE_HEIGHT;
vDelta = 0;
gDelta = 0.25f;
// This is how much the re-bound will degrade on each cycle...
rbDegDelta = 2.5f;
InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap am = getActionMap();
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_SPACE, 0), "jump");
am.put("jump", new AbstractAction() {
#Override
public void actionPerformed(ActionEvent e) {
// Can only bound when we're actually on the ground...
// You might want to add fudge factor here so that the
// sprite can be within a given number of pixels in order to
// jump again...
if (yPos + SPRITE_HEIGHT == getHeight()) {
vDelta = -8;
rbDelta = vDelta;
bounce = true;
}
}
});
engine = new Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
int height = getHeight();
// No point if we've not been sized...
if (height > 0) {
// Are we bouncing...
if (bounce) {
// Add the vDelta to the yPos
// vDelta may be postive or negative, allowing
// for both up and down movement...
yPos += vDelta;
// Add the gravity to the vDelta, this will slow down
// the upward movement and speed up the downward movement...
// You may wish to place a max speed to this
vDelta += gDelta;
// If the sprite is not on the ground...
if (yPos + SPRITE_HEIGHT >= height) {
// Seat the sprite on the ground
yPos = height - SPRITE_HEIGHT;
// If the re-bound delta is 0 or more then we've stopped
// bouncing...
if (rbDelta >= 0) {
// Stop bouncing...
bounce = false;
} else {
// Add the re-bound degregation delta to the re-bound delta
rbDelta += rbDegDelta;
// Set the vDelta...
vDelta = rbDelta;
}
}
}
}
repaint();
}
});
engine.start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
int width = getWidth() - 1;
int xPos = (width - SPRITE_WIDTH) / 2;
g2d.drawOval(xPos, yPos, SPRITE_WIDTH, SPRITE_HEIGHT);
g2d.dispose();
}
}
}

Well I can think of one way. It involves some complex amounts of math (parabola). So i'm going to provide a very simple answer.
int y = 0;
and in the method that tests for the spacebar...
if (y !< 1){
if (y < 30){
y += 1;
}
if (y > 30){
y -= 1;
}
}
I haven't tested it out yet, but it should work in theory....But it won't animate anything, this code is only going to take the sprites Y value and make it go up. That's just about the easiest jumping method that can exist....

Java 2D Game dev: Multiple key input

I'm trying to get the controls working for a 2D game written in Java. However, I'm encountering an odd bug in movement. Whenever I'm trying to use the up and left controls while firing (space bar), or down and right while firing, the game is unable to detect the pressing of the space bar. Below are the relevant code excerpts:
import java.awt.Image;
import java.awt.event.KeyEvent;
import java.util.ArrayList;
import javax.swing.ImageIcon;
public class Player {
private String playerPath = "images/craft.png";
private int x, y, dx, dy;
private Image image;
private ArrayList missiles;
private final int CRAFT_SIZE = 20;
public Player() {
ImageIcon ii = new ImageIcon(playerPath);
image = ii.getImage();
missiles = new ArrayList();
x = 20;
y = 20;
}
public void keyPressed(KeyEvent e) {
int key = e.getKeyCode();
if (key == KeyEvent.VK_SPACE) {
fire();
}
if (key == KeyEvent.VK_LEFT) {
dx = -1;
}
if (key == KeyEvent.VK_RIGHT) {
dx = 1;
}
if (key == KeyEvent.VK_UP) {
dy = -1;
}
if (key == KeyEvent.VK_DOWN) {
dy = 1;
}
}
public void keyReleased(KeyEvent e) {
int key = e.getKeyCode();
if (key == KeyEvent.VK_LEFT) {
dx = 0;
}
if (key == KeyEvent.VK_RIGHT) {
dx = 0;
}
if (key == KeyEvent.VK_UP) {
dy = 0;
}
if (key == KeyEvent.VK_DOWN) {
dy = 0;
}
}
public void fire() {
missiles.add(new Projectile(x + CRAFT_SIZE, y + CRAFT_SIZE/2));
}
}//end class Player
And
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
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 java.util.ArrayList;
import javax.swing.JPanel;
import javax.swing.Timer;
public class Game extends JPanel implements ActionListener {
private Player player;
private Timer timer;
private int winHeight;
private int winWidth;
private final int UP = KeyEvent.VK_UP;
private final int DOWN = KeyEvent.VK_DOWN;
private final int LEFT = KeyEvent.VK_LEFT;
private final int RIGHT = KeyEvent.VK_RIGHT;
private final int SPACE = KeyEvent.VK_SPACE;
public Game(int w, int h) {
addKeyListener(new TAdapter());
setBackground(Color.BLACK);
addKeyListener(new TAdapter());
setFocusable(true);
setDoubleBuffered(true);
player = new Player();
winHeight = h;
winWidth = w;
timer = new Timer(5, this);
timer.start();
}
#Override
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2d = (Graphics2D) g;
g2d.drawImage(player.getImage(), player.getX(), player.getY(), this);
ArrayList proj = player.getMissiles();
for (Object p : proj) {
Projectile b = (Projectile) p;
g2d.drawImage(b.getImage(), b.getX(), b.getY(), this);
}
Toolkit.getDefaultToolkit().sync();
g.dispose();
}
#Override
public void actionPerformed(ActionEvent e) {
// Update projectile locations
ArrayList ms = player.getMissiles();
for (int i = 0; i < ms.size(); i++) {
Projectile p = (Projectile) ms.get(i);
if (p.getX() <= winWidth) {
p.move();
} else {
ms.remove(p);
}
}
player.move();
repaint();
}
private class TAdapter extends KeyAdapter {
#Override
public void keyReleased(KeyEvent e) {
player.keyReleased(e);
}
#Override
public void keyPressed(KeyEvent e) {
player.keyPressed(e);
}
}// end class TAdapter
}// end class Game

Whenever I'm trying to use the up and left controls while firing (space bar), or down and right while firing, the game is unable to detect the pressing of the space bar.
KeyEvents are only generated for the last key pressed. If you want to handle multiple keys being pressed at the same time then you need to:
keep track of a key that has been pressed/released
use a Swing Timer to schedule the animation.
Then whenever the timer fires you check which keys are currently pressed and the do the action for that key.

Using a JLabel to continuously update a score in Java, JFrame-based game

I'm building a little "pong" game in Java.
I'm trying to add a scorekeeper up top that shows the updated score (+1) everytime the player saves the ball with the paddle.
I'm trying to use a JLabel but the problem is that I can't think of a way to continuously update the JLabel each time the paddle is hit.
Any ideas?
My code:
MainPanel Class (the one with the Paddle and Ball and Label)
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
//import swing.graphics.BounceFrame;
//import swing.graphics.Circle;
public class MainPanel extends JPanel implements ActionListener, KeyListener, Runnable{
public Paddle paddle;
public Ball ball;
public MainPanel(){
ball = new Ball(50, 50, 10); //centerX, centerY, radius
setSize(300, 300);
paddle = new Paddle();
JLabel scoreKeeper = new JLabel("Score" + ball.getScore());
add(scoreKeeper);
Thread thread = new Thread(this);
thread.start();
}
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2 = (Graphics2D)g;
paddle.draw(g2);
ball.draw(g2);
}
public void actionPerformed(ActionEvent e) {
String direction = e.getActionCommand();
switch(direction){
case "left": Paddle.movePaddleLeft(); break;
case "right": Paddle.movePaddleRight(); break;
}
this.repaint();
}
public void run() {
try {
while(true){
ball.move(getBounds());
repaint();
Thread.sleep(500/30);
}
}
catch (Exception e) {
e.printStackTrace();
}
}
#Override
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == 37){
Paddle.movePaddleLeft();
}
if (e.getKeyCode() == 39){
Paddle.movePaddleRight();
}
}
#Override
public void keyReleased(KeyEvent e) {
}
#Override
public void keyTyped(KeyEvent e) {
}
}
And my Ball class:
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;
import java.util.Random;
public class Ball {
private Ellipse2D ball;
private double radius;
private double ballCircumference;
private Color color;
private double x;
private double y;
private double dx = 5;
private double dy = 5;
private int score = 0;
public int getScore() {
return score;
}
//Boundaries to determine if ball is hit by paddle
private double criticalBoundaryX;
private double criticalBoundaryY1;
private double criticalBoundaryY2;
private double paddleHalfwayPoint;
private boolean inGame = true;
public void recalculateCriticals(){
criticalBoundaryX = Paddle.getYPosition() - ballCircumference;
criticalBoundaryY1 = Paddle.getXPosition()- ballCircumference; //Left boundary
criticalBoundaryY2 = Paddle.getXPosition()+Paddle.getPaddleWidth()+ballCircumference; //Right Boundary
paddleHalfwayPoint = (Paddle.getXPosition()+Paddle.getPaddleWidth())/2;
}
public Ball(int centerX, int centerY, int radius) {
this.x = centerX - radius;
this.y = centerY - radius;
this.radius = radius;
ballCircumference = 2*radius;
Random randomRGB = new Random();
color = new Color(randomRGB.nextInt(255), randomRGB.nextInt(255), randomRGB.nextInt(255));
this.ball = new Ellipse2D.Double(x, y, 2*radius, 2*radius);
}
public void move(Rectangle2D bounds) {
recalculateCriticals();
x += dx;
y += dy;
if (x < bounds.getMinX()) {
x = bounds.getMinX();
dx = -dx;
}
if (x + 2*radius >= bounds.getMaxX()) {
//System.out.println(bounds.getMaxX());
x = bounds.getMaxX() - 2*radius;
dx = -dx;
}
if (y < bounds.getMinY()) {
y = bounds.getMinY();
dy = -dy;
}
if (y > criticalBoundaryX){
if (x < criticalBoundaryY1 || x > criticalBoundaryY2){
inGame = false;
}
if (!inGame && hittingEdge(x))
dx = -dx;
}
if (y > criticalBoundaryX && inGame){ //When it hits the paddle
changeColor();
score++;
y = criticalBoundaryX;
dy = -dy;
}
if (y > bounds.getMaxY()){
System.out.println("Game Over");
System.exit(0);
}
recalculateCriticals();
ball.setFrame(x, y, 2*radius, 2*radius);
}
public boolean onPaddle(double x){
return ((x > Paddle.getXPosition()) && (x < Paddle.getXPosition()+Paddle.getPaddleWidth()) && (y > Paddle.getYPosition()-10));
}
public boolean hittingEdge(double x){
return ((x >= criticalBoundaryY1 && x < paddleHalfwayPoint)
||
(x <= criticalBoundaryY1 && x > paddleHalfwayPoint)); //Return true if x is hitting the side edge of the paddle
}
public void changeColor(){
Random randomColor = new Random();
color = new Color(randomColor.nextInt(255), randomColor.nextInt(255), randomColor.nextInt(255));
}
public void draw(Graphics2D g2) {
g2.setColor(color);
g2.fill(ball);
}
}

The "Java way" of doing this would be to define a listener interface, for example:
public interface BallListener {
void paddleHit();
}
In the Ball class, you should add a field
private List<BallListener> listeners;
as well as methods
public void addBallListener(BallListener l) { listeners.add(l); }
public void removeBallListener(BallListener l) { listeners.remove(l); }
When the paddle is hit, you go:
for (BallListener l : listeners)
l.paddleHit();
The main class should implement the BallListener interface, and register itself with the ball (ball.addBallListener(this)).
This approach also enables you to, when needed, inform other parts of your program about different events that happen to the ball (i.e. add a new method to BallListener for each event you'd like to signal).

Lag in simple side scrolling game in Java

I recently built my first simple side scrolling game in java, but I'm experiencing some lag and I don't know why. When I move my character sideways it seems to be changing speed, most of the time going fast but sometimes slowing down. It makes the feel of the game very odd. I hope someone can point me in the right direction here, I'll post my classes below:
Main Class:
public class MainGame {
public static void main(String[] args) {
Frame frame = new Frame();
}
}
Frame Class:
import javax.swing.JFrame;
public class Frame extends JFrame{
public Frame(){
add(new Board());
setTitle("2-D Test Game");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(800,325);
this.setResizable(false);
setLocationRelativeTo(null);
setVisible(true);
}
}
Board Class:
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.*;
public class Board extends JPanel implements ActionListener{
private Player p;
private Timer timer;
private Image background;
public Board(){
super();
p = new Player();
addKeyListener(new ActionListener());
setFocusable(true);
ImageIcon i = new ImageIcon("C:/test.png");
background = i.getImage();
timer = new Timer(5,this);
timer.start();
}
public void actionPerformed(ActionEvent arg0) {
p.move();
repaint();
}
public void paint(Graphics g){
super.paint(g);
Graphics2D g2d = (Graphics2D) g;
g2d.drawImage(background,p.nx,0,null);
g2d.drawImage(p.getImage(), 350, p.getY(), null);
}
private class ActionListener extends KeyAdapter{
public void keyReleased(KeyEvent e){
p.keyReleased(e);
}
public void keyPressed(KeyEvent e){
p.keyPressed(e);
}
}
}
Player Class:
import java.awt.Image;
import java.awt.event.KeyEvent;
import javax.swing.*;
public class Player {
private Image img;
int x,y,dx,dy,nx;
long time;
private final int SPEED = 2;
private final int GRAV = 1;
boolean left,right,isJumping;
public Player(){
ImageIcon i = new ImageIcon("C:/plager.png");
img = i.getImage();
x = 350;
y = 160;
dx = 0;
dy = 0;
nx = 0;
left = false;
right = false;
isJumping = false;
}
public void move(){
x += dx;
nx = (nx-dx);
}
public int getX(){
return x;
}
public int getY(){
return y;
}
public Image getImage(){
return img;
}
public void keyReleased(KeyEvent e) {
int code = e.getKeyCode();
if(code == KeyEvent.VK_LEFT){
left = false;
if(right){
dx = SPEED;
}else{
dx = 0;
}
}else if(code == KeyEvent.VK_RIGHT){
right = false;
if(left){
dx = -SPEED;
}else{
dx = 0;
}
}
}
public void keyPressed(KeyEvent e) {
int code = e.getKeyCode();
if(code == KeyEvent.VK_LEFT){
left = true;
dx = -SPEED;
}else if(code == KeyEvent.VK_RIGHT){
right = true;
dx = SPEED;
}
}
}

Timer does not have a real time guarantee. So, you should calculate the time difference from the last time move was called and multiply that by the amount you are moving. It will make the numbers smaller so I would add another const to make it larger. It's actually better get the time delta in actionPerformed (or another process method) and pass it to all of the process or move methods so everything moves using the same time delta.