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How can I move a jlabel image around the screen?

I want to click on the screen and have the character move to that destination. Not instantly, but rather "walk" to the given coordinate. Currently I'm using JLabels and they're fine if I only use static images, but everytime I click somewhere on the screen the image shows up at that exact point. Could someone give me some tips?
edit: Should I override the paint class and draw some items that way?
Here's some code:
package mod;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.Toolkit;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.beans.PropertyChangeEvent;
import java.io.File;
import java.io.IOException;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.awt.KeyboardFocusManager;
import javax.imageio.ImageIO;
import javax.swing.*;
public class Board2 extends JPanel {
private Thread animator;
int x, y;
double ix, iy;
double dx, dy;
final int frameCount = 8;
BufferedImage flower;
private int[][] fPos = {{232, 15},{400, 200},{335, 335}}; // flower coordinates
private static int bWIDTH = 800; // width of window
private static int bHEIGHT = 600;// height of window
private Font font;
private FontMetrics metrics;
ImageIcon grassI = new ImageIcon(this.getClass().getResource("grass.png"));
ImageIcon riverI = new ImageIcon(this.getClass().getResource("river.png"));
private Image grass = grassI.getImage();
private Image river = riverI.getImage();
private House house = new House();
private River river1 = new River();
//private Flower flower = new Flower();
private TitleScreenLayer ts = new TitleScreenLayer();
private Player girlP = new Player();
private static int px = 250;
private static int py = 250;
private boolean visTl = false;
private boolean plant = false;
ArrayList<Flower> flowers= new ArrayList<Flower>();
private long period;
private volatile boolean running = false;
private volatile boolean gameOver = false;
private volatile boolean isPaused = false;
// New stuff for Board2 below
private JLayeredPane lpane;
private JLabel grassLabel;
private JLabel riverLabel;
private JLabel houseLabel;
private JLabel pear1Label;
private JLabel pear2Label;
private JLabel pear3Label;
private JLabel drivewayLabel;
private JLabel girlLabel;
private JProgressBar progressBar;
private JLabel toolLabel;
private JTextArea textBubble;
ImageIcon girlImage = new ImageIcon(girlP.getImage());
int mouseClicks = 0;
CountdownTimer cTimer;
private static String message;
public static String setMessage(String newMessage){
return message = newMessage;
}
private static ImageIcon playerTool = new ImageIcon("BradfordPear.png");
public ImageIcon getPlayerTool(){
return playerTool;
}
public static void setPlayerTool(String image){
playerTool = new ImageIcon(image);
}
public JTextArea getTextBubble(){
return textBubble;
}
public Player getPlayer(){
return girlP;
}
public static int getPlayerX(){
return px;
}
public static int getPlayerY(){
return py;
}
public JLayeredPane getLayeredPane(){
return lpane;
}
public Board2(){
setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
//create the layered pane
lpane = new JLayeredPane();
lpane.setPreferredSize(new Dimension(800, 600));
//create the "background" image
ImageIcon image = new ImageIcon("grass.png");
grassLabel = new JLabel(image);
grassLabel.setBounds(0, 0, image.getIconWidth(), image.getIconHeight());
//create the house image
ImageIcon houseImage = new ImageIcon("house.png");
houseLabel = new JLabel(houseImage);
houseLabel.setBounds(-330, -150, image.getIconWidth(), image.getIconHeight());
//create the driveway image
ImageIcon drivewayImage = new ImageIcon("driveway.png");
drivewayLabel = new JLabel(drivewayImage);
drivewayLabel.setBounds(-335, 105, image.getIconWidth(), image.getIconHeight());
//create the river image
ImageIcon riverImage = new ImageIcon("river.png");
riverLabel = new JLabel(riverImage);
riverLabel.setBounds(360, 0, image.getIconWidth(), image.getIconHeight());
//create pear1 image
ImageIcon pear1Image = new ImageIcon("BradfordPear.png");
pear1Label = new JLabel(pear1Image);
pear1Label.setBounds(100, 100, image.getIconWidth(), image.getIconHeight());
//create pear2 image
ImageIcon pear2Image = new ImageIcon("BradfordPear.png");
pear2Label = new JLabel(pear2Image);
pear2Label.setBounds(50, -100, image.getIconWidth(), image.getIconHeight());
//create pear3 image
ImageIcon pear3Image = new ImageIcon("BradfordPear.png");
pear3Label = new JLabel(pear3Image);
pear3Label.setBounds(-100, -50, image.getIconWidth(), image.getIconHeight());
//create initial Player(girl) image
//ImageIcon girlImage = new ImageIcon(girlP.getImage());
girlLabel = new JLabel(girlImage);
girlLabel.setBounds((int)girlP.getPositionX(), (int)girlP.getPositionY(), image.getIconWidth(), image.getIconHeight());
//create progress bar
progressBar = new JProgressBar(JProgressBar.VERTICAL, 0, 10);
progressBar.setValue(0);
progressBar.setBounds(720, 50, 100, 500);
//create timer
JTextField timerField = new JTextField();
cTimer = new CountdownTimer(timerField);
timerField.setBounds(400, 0, 50, 50);
//create toolbox
Toolbox toolbox = new Toolbox();
toolbox.setBounds(550, 0, 250, 50);
//create the text bubble
textBubble = new JTextArea("IDPC is the best coding group ever");
textBubble.setLineWrap(true);
//textBubble.setBounds(200, 200, 100, 100);
//add the background & various images
lpane.add(grassLabel, new Integer(1));
lpane.add(houseLabel, new Integer(2));
lpane.add(riverLabel, new Integer(2));
lpane.add(drivewayLabel, new Integer(2));
lpane.add(pear1Label, new Integer(2));
lpane.add(pear2Label, new Integer(2));
lpane.add(pear3Label, new Integer(2));
lpane.add(progressBar, new Integer(3));
lpane.add(girlLabel, new Integer(3));
lpane.add(timerField, new Integer(2));
lpane.add(toolbox, new Integer(3));
add(lpane);
cTimer.start();
// listen for action events
new ActionListener() {
public void actionPerformed(ActionEvent e) {
girlP.move();
//girlLabel.setLocation(px, py);
}
};
// listen for mouse presses
addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
//lpane.remove(textBubble);
mouseClicks+= 1;
testPress(e.getX(), e.getY());
//textBubble.setBounds(e.getX(), e.getY(), 40, 40);
updateProgressBar();
}
});
//listen for player action
addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
if(e.getClickCount() == 2){
ImageIcon flowerImage = playerTool;
JLabel flowerPanel = new JLabel(flowerImage);
flowerPanel.setBounds((px -((int)girlP.getPositionX() / 2)),
(py - ((int)girlP.getPositionY() / 2)),
flowerImage.getIconWidth(),
flowerImage.getIconHeight());
lpane.add(flowerPanel, new Integer(3));
textBubble.setBounds(e.getX(), e.getY(), 200, 40);
textBubble.replaceSelection(message);
lpane.add(textBubble, new Integer(3));
//lpane.remove(textBubble);
}
}
});
x = 15;
y = 150;
ix = 0;
iy = 0;
dx = .05;
dy = .05;
girlP.setDestination(px, py);
}
public void testPress(int x, int y){
px = x;
py = y;
if (px < (ix + house.getImage().getWidth(this))
&& (py < (iy + house.getImage().getHeight(this)))) {
px = px + (house.getImage().getWidth(this)/3);
py = py + (house.getImage().getHeight(this)/3);
}
if (px > (bWIDTH - river1.getImage().getWidth(this))) {
px = px - 80 - (river1.getImage().getWidth(this)/2);
}
girlLabel.setBounds((px -((int)(girlP.getPositionX()*2.5))),
(py - ((int)(girlP.getPositionY()*2.5))),
girlImage.getIconWidth(), girlImage.getIconHeight());
girlP.setDestination((px-(girlP.getImage().getWidth(this)/2)),
(py-(girlP.getImage().getHeight(this)/2)));
girlP.pinned(x, y);
}
public void updateProgressBar(){
if(progressBar.getValue() == 3){
//progressBar.setBackground(Color.red);
//UIManager.put("progressBar.foreground", Color.RED);
UIDefaults defaults = new UIDefaults();
defaults.put("progressBar[Enabled].foregroundPainter", Color.RED);
progressBar.putClientProperty("Nimbus.Overrides.InheritDefaults", Boolean.TRUE);
progressBar.putClientProperty("Nimbus.Overrides", defaults);
}
progressBar.setValue(mouseClicks);
}
/**
* Create the GUI and show it. For thread safety,
* this method should be invoked from the
* event-dispatching thread.
*/
private static void createAndShowGUI() {
//Create and set up the window.
JFrame frame = new JFrame("Game");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Create and set up the content pane.
JComponent newContentPane = new TitleScreenLayer();
newContentPane.setOpaque(true); //content panes must be opaque
frame.setContentPane(newContentPane);
//Display the window.
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
//Schedule a job for the event-dispatching thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
Here's the player class:
package mod;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.ImageObserver;
import java.awt.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.io.*;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
public class Player {
int tile;
double positionX;
double positionY;
int destinationX;//Used when moving from place to place
int destinationY;
Tool currentTool;
int direction; //Position the image is facing
double dx;
double dy;
int [] pin = new int[10];
private String girl = "girl.png";
ImageIcon ii = new ImageIcon(this.getClass().getResource(girl)); // load girl image
private Image image = ii.getImage();
private boolean visible = true;
public boolean plant = false;
Image playerImage;
public double getPositionX() {
return positionX;
}
public void setPositionX(double positionX) {
this.positionX = positionX;
}
public double getPositionY() {
return positionY;
}
public void setPositionY(double positionY) {
this.positionY = positionY;
}
public Player(){
positionX=30;
positionY=20;
dx = 0.2;
dy = 0.2;
destinationX=(int)positionX;
destinationY=(int)positionY;
//this.playerImage=playerImage;
}
public void doAction() {
//currentTool.getNum();
plant = true;
}
public void pinned(int x, int y) {
if (plant == true) {
pin[0] = x;
pin[1] = y;
}
//plant = false;
}
public void plant(Graphics g, ImageObserver io) {
int x = pin[0];
int y = pin[1];
if (plant == true) {
// g.drawImage(flower.getImage(), x, y, io);
}
}
public void ActionPerformed(ActionEvent e) {
positionX += dx;
positionY += dy;
}
public boolean isVisible() {
return visible;
}
public void setVisible(Boolean visible) {
this.visible = visible;
}
public Image getImage() {
return image;
}
public void move(){
//MOVE LEFT AND RIGHT
if(destinationX<positionX){
positionX-=dx;
}
if(destinationX>positionX){
positionX+=dx;
}
//MOVE UP AND DOWN
if(destinationY<positionY){
positionY-=dy;
}
if(destinationY>positionY){
positionY+=dy;
}
}
public double setDx(double speed) {
dx = speed;
return dx;
}
public double setDy(double speed) {
dy = speed;
return dy;
}
public void TileIn(int px, int py)
{
px=destinationX;
py=destinationY;
int tileX=1;
int tileY = 1;
int bWIDTH=800;
int bHEIGHT=600;
if(px >= 0 && px <= 800*.1)
{
tileX=2;
}
else if(px> bWIDTH*.1 && px <= bWIDTH*.2)
{
tileX=3;
}
else if(px > bWIDTH*.2 && px <= bWIDTH*.3)
{
tileX=4;
}
else if(px > bWIDTH*.3 && px <= bWIDTH*.4)
{
tileX=5;
}
else if(px > bWIDTH*.4 && px <= bWIDTH*.5)
{
tileX=6;
}
else if(px > bWIDTH*.5 && px <= bWIDTH*.6)
{
tileX=7;
}
else if(px > bWIDTH*.6 && px <= bWIDTH*.7)
{
tileX=8;
}
else if(px > bWIDTH*.7 && px <= bWIDTH*.8)
{
tileX=9;
}
else if(px > bWIDTH*.8 && px <= bWIDTH*.9)
{
tileX=10;
}
else if(px > bWIDTH*.9 && px <= bWIDTH)
{
tileX=11;
}
if(py >= 0 && py <= bHEIGHT*.1)
{
tileY=2;
}
else if(py> bHEIGHT*.1 && py <= bHEIGHT*.2)
{
tileY=3;
}
else if(py > bHEIGHT*.2 && py <= bHEIGHT*.3)
{
tileY=4;
}
else if(py > bHEIGHT*.3 && py <= bHEIGHT*.4)
{
tileY=5;
}
else if(py > bHEIGHT*.4 && py <= bHEIGHT*.5)
{
tileY=6;
}
else if(py > bHEIGHT*.5 && py <= bHEIGHT*.6)
{
tileY=7;
}
else if(py > bHEIGHT*.6 && py <= bHEIGHT*.7)
{
tileY=8;
}
else if(py > bHEIGHT*.7 && py <= bHEIGHT*.8)
{
tileY=9;
}
else if(py > bHEIGHT*.8 && py <= bHEIGHT*.9)
{
tileY=10;
}
else if(py > bHEIGHT*.9 && py <= bHEIGHT)
{
tileY=11;
}
System.out.println("Grid X: " + tileX + " Grid Y: " + tileY);
}
public void setDestination(int x, int y){
destinationX=x;
destinationY=y;
System.out.println(x + "," + y);
TileIn(x,y);
}
// public void tileIn(int a)
// {
//
// b=destinationY;
// return TileIn(x,y)
// }
public void draw(Graphics g,ImageObserver io){
g.drawImage(image, (int)positionX,(int) positionY,io);
}
}
Here is the main class:
package mod;
import java.awt.Container;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import javax.swing.JFrame;
public class Skeleton2 extends JFrame /*implements WindowListener*/{
private static int DEFAULT_FPS = 80;
private Board2 bd;
public Skeleton2(long period) {
super("Skeleton");
makeGUI(period);
//addWindowListener(this);
pack();
setResizable(false);
setVisible(true);
}
public void makeGUI(long period) {
Container c = getContentPane();
bd = new Board2();
c.add(bd, "Center");
} // end of makeGUI()
//==================================================================================
// Window Events
//==================================================================================
/*
public void windowActivated(WindowEvent e) {
bd.resumeGame();
}
public void windowDeactivated(WindowEvent e) {
bd.pauseGame();
}
public void windowDeiconified(WindowEvent e) {
bd.resumeGame();
}
public void windowIconified(WindowEvent e) {
bd.pauseGame();
}
public void windowClosing(WindowEvent e) {
bd.stopGame();
}
*/
public void windowClosed(WindowEvent e) {}
public void windowOpened(WindowEvent e) {}
//==================================================================================
public static void main(String[] args) {
int fps = DEFAULT_FPS;
long period = (long) 1000.0/fps;
new Skeleton2(period);
System.out.println("Period: " + period);
}
}

Not instantly, but rather "walk" to the given coordinate.
Then you need to use a Swing Timer. The Timer is used to schedule the animation. So you would need to calculate a path between the two points. Every time the Timer fires you would move the label a few pixels until it reaches it's destination.
There is no need to do custom painting for this. A JLabel will work fine. The hard part is calculating the path you want the character to take. Also make sure you use a null layout on the panel you add the JLabel to, which means you will also need to set the size of the label equal to the preferred size of the label.

You should rather use g.drawImage in your component paintComponent method.

how to notify multithread event on swing game

I am supposed to make a little game simulation. in this game there are three button . when user click start tank and car will close each other in 90 degrees when user click shut button tank will throw bullet to car.
i made and a simulation for this. tank throw bullet to car but when bullet crash car i couldn't this. i just need increase score of how many times tank hit car.
here is the source code
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.JPanel;
public class Vehicle extends Thread {
private JPanel box;
private int XSIZE;
private int YSIZE;
private int time;
private int x;
private int y;
private int dx = 5;
private int dy = 5;
private int dim;
public Vehicle(JPanel b, int i) {
box = b;
this.dim = i;
if (i == 0) {
x = 0;
y = 100;
time = 1000;
XSIZE = 9;
YSIZE = 20;
} else {
time = 200;
y = box.getSize().height;
x = box.getSize().width / 2;
XSIZE = 6;
YSIZE = 10;
}
}
public void draw() {
Graphics g = box.getGraphics();
g.fillOval(x, y, XSIZE, YSIZE);
g.dispose();
}
public void moveHorizontal() {
if (!box.isVisible())
return;
Graphics g = box.getGraphics();
g.setColor(Color.BLUE);
g.setXORMode(box.getBackground());
g.fillOval(x, y, XSIZE, YSIZE);
x += dx;
Dimension d = box.getSize();
if (x < 0) {
x = 0;
dx = -dx;
}
if (x + XSIZE >= d.width) {
x = d.width - XSIZE;
dx = -dx;
}
g.fillOval(x, y, XSIZE, YSIZE);
g.dispose();
}
public JPanel getBox() {
return box;
}
public void setBox(JPanel box) {
this.box = box;
}
public void moveVertical() {
if (!box.isVisible())
return;
Graphics g = box.getGraphics();
g.setXORMode(box.getBackground());
g.fillOval(x, y, XSIZE, YSIZE);
y += dy;
Dimension d = box.getSize();
if (y < 0) {
y = 0;
dy = -dy;
}
if (y + YSIZE >= d.height) {
y = d.height - YSIZE;
dy = -dy;
}
g.fillOval(x, y, XSIZE, YSIZE);
g.dispose();
}
public void move(int i) {
if (i == 0) {
moveHorizontal();
} else {
moveVertical();
}
}
public int getYSIZE() {
return YSIZE;
}
public void setYSIZE(int ySIZE) {
YSIZE = ySIZE;
}
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public int getXSIZE() {
return XSIZE;
}
public void setXSIZE(int xSIZE) {
XSIZE = xSIZE;
}
public void setY(int y) {
this.y = y;
}
public void run() {
try {
draw();
for (;;) {
move(dim);
sleep(time);
}
} catch (InterruptedException e) {
}
}
}
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.JPanel;
public class Bullet extends Thread {
private JPanel box;
private int XSIZE = 3;
public int getXSIZE() {
return XSIZE;
}
public void setXSIZE(int xSIZE) {
XSIZE = xSIZE;
}
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
private int YSIZE = 1;
private int x;
private int y;
private int dx = 3;
public Bullet(JPanel b, Vehicle tank, Vehicle car) {
box = b;
x = tank.getX() + tank.getXSIZE();
if (x >= tank.getBox().getSize().width / 2)
dx = -dx;
y = tank.getY() + tank.getYSIZE() / 2;
;
}
public void draw() {
Graphics g = box.getGraphics();
g.fillOval(x, y, XSIZE, YSIZE);
g.dispose();
}
public void move() {
if (!box.isVisible())
return;
Graphics g = box.getGraphics();
g.setColor(Color.RED);
g.setXORMode(box.getBackground());
g.fillOval(x, y, XSIZE, YSIZE);
x += dx;
Dimension d = box.getSize();
if (x < 0) {
x = 0;
}
if (x + XSIZE >= d.width) {
x = d.width - XSIZE;
}
g.fillOval(x, y, XSIZE, YSIZE);
g.dispose();
}
public void run() {
try {
draw();
for (;;) {
move();
sleep(20);
}
} catch (InterruptedException e) {
}
}
}
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JLabel;
#SuppressWarnings("serial")
public class Tank_Shut_Car_ThreadFrame extends JFrame {
private JPanel canvas;
private boolean isOn = false;
private Vehicle tank;
private Vehicle car;
private JLabel score;
public static int sc = 0;
public Tank_Shut_Car_ThreadFrame() {
setResizable(false);
setSize(600, 400);
setTitle("Tank Shut Car");
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
Container contentPane = getContentPane();
canvas = new JPanel();
contentPane.add(canvas, "Center");
canvas.setLayout(null);
score = new JLabel("0");
score.setBounds(527, 11, 36, 14);
canvas.add(score);
JLabel lblScore = new JLabel("score");
lblScore.setBounds(481, 11, 36, 14);
canvas.add(lblScore);
JPanel p = new JPanel();
addButton(p, "Start", new ActionListener() {
public void actionPerformed(ActionEvent evt) {
if (!isOn) {
tank = new Vehicle(canvas, 0);
tank.start();
car = new Vehicle(canvas, 1);
car.start();
isOn = true;
}
}
});
addButton(p, "Shut", new ActionListener() {
public void actionPerformed(ActionEvent evt) {
if (isOn) {
Bullet bullet = new Bullet(canvas, tank, car);
bullet.start();
score.setText("" + sc);
}
}
});
addButton(p, "Close", new ActionListener() {
public void actionPerformed(ActionEvent evt) {
canvas.setVisible(false);
System.exit(0);
}
});
contentPane.add(p, "South");
}
public void addButton(Container c, String title, ActionListener a) {
JButton button = new JButton(title);
c.add(button);
button.addActionListener(a);
}
}
import javax.swing.JFrame;
public class Test {
public static void main(String[] args) {
JFrame frame = new Tank_Shut_Car_ThreadFrame();
frame.setVisible(true);
}
}

Okay, so I had a play around with this (just for fun)
Now, this is far from a "proper" or "complete" game engine, but it provides a basic idea of how it might be possible to mix a core thread engine with UI components.
Rather then pasting the entire code, I've uploaded the source it to Tank.zip
But the basic engine looks like this...
public class GameEngine extends Thread {
public static final Object ASSET_LOCK = new Object();
private List<GameAsset> lstAssets;
private GameScreen screen;
public GameEngine(GameScreen screen) {
// Let the thread die when the JVM closes
setDaemon(true);
// Want to be below the UI thread (personal preference)
setPriority(NORM_PRIORITY - 1);
// A list of game assests
lstAssets = new ArrayList<GameAsset>(25);
// A reference to the screen
this.screen = screen;
// Add global key listener, this is simpler to the trying to attach a key listener
// to the screen.
Toolkit.getDefaultToolkit().addAWTEventListener(new EventHandler(), AWTEvent.KEY_EVENT_MASK);
}
public GameAsset[] getAssets() {
synchronized (ASSET_LOCK) {
return lstAssets.toArray(new GameAsset[lstAssets.size()]);
}
}
/*
* Allows for assets to be added
*/
public void addAsset(GameAsset asset) {
synchronized (ASSET_LOCK) {
lstAssets.add(asset);
}
}
#Override
public void run() {
while (true) {
try {
sleep(40);
} catch (InterruptedException ex) {
}
synchronized (ASSET_LOCK) {
GameAsset[] assets = lstAssets.toArray(new GameAsset[lstAssets.size()]);
for (GameAsset asset : assets) {
if (lstAssets.contains(asset)) {
asset.update(this, screen);
}
}
screen.repaint(new ArrayList<GameAsset>(lstAssets));
}
}
}
/**
* Allows the removal of an asset...
*/
public void removeAsset(GameAsset asset) {
synchronized (ASSET_LOCK) {
lstAssets.remove(asset);
}
}
/**
* Key event handling...
*/
protected class EventHandler implements AWTEventListener {
#Override
public void eventDispatched(AWTEvent event) {
KeyEvent keyEvent = (KeyEvent) event;
if (keyEvent.getID() == KeyEvent.KEY_PRESSED) {
synchronized (ASSET_LOCK) {
GameAsset[] assets = lstAssets.toArray(new GameAsset[lstAssets.size()]);
for (GameAsset asset : assets) {
if (lstAssets.contains(asset)) {
asset.processKeyPressed(GameEngine.this, screen, keyEvent);
}
}
}
} else if (keyEvent.getID() == KeyEvent.KEY_RELEASED) {
synchronized (ASSET_LOCK) {
GameAsset[] assets = lstAssets.toArray(new GameAsset[lstAssets.size()]);
for (GameAsset asset : lstAssets) {
if (lstAssets.contains(asset)) {
asset.processKeyReleased(GameEngine.this, screen, keyEvent);
}
}
}
}
}
}
}

Swing is not thread safe. Events should be fired on the event-dispatching thread.
http://www.javamex.com/tutorials/threads/invokelater.shtml

Collision detection using plain arrays and rectangles--java

I am almost done with my first little java game for my final project. It is a sidescroller where you have to shoot/avoid asteroids. My last problem is figuring out how to make my array of asteroids collide with the player's lasers. Here's what I have so far, there's an "AWT-EventQueue-0" java.lang.NullPointerException" on line 137, that I can't deal with. Any help is appreciated.
Edit: I added in my other classes, I realize it would be hard to judge the functionality of my code if I didn't show you where it came from.
package ShooterGame;
import java.applet.Applet;
import java.applet.AudioClip;
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import java.util.Random;
import javax.swing.*;
public class Board extends JPanel implements ActionListener
{
Enemy[] baddies = new Enemy[10000];
Player p;
Image img;
int y;
Timer time;
boolean lost = false;
static Font font = new Font("SanSerif", Font.BOLD, 24);
public AudioClip theme, bang, laser;
static ArrayList<Enemy> enemies;
public static int score = 0;
public static int lives = 5;
public Board()
{
p = new Player();
addKeyListener(new ActionListener());
setFocusable(true);
ImageIcon i = new ImageIcon("images/background.png");
img = i.getImage();
time = new Timer(5, this);
time.start();
for(int j = 0; j < baddies.length; j++)
{
Random ran = new Random();
y = ran.nextInt(365)+1;
baddies[j]= new Enemy((100*j + 700), y, "images/asteroid.gif");
}
theme = Applet.newAudioClip(getClass().getResource("theme.mid"));
theme.play();
bang = Applet.newAudioClip(getClass().getResource("bang.wav"));
}
public void actionPerformed(ActionEvent e)
{
checkCollisions();
ArrayList<?> bullets = Player.getBullets();
for(int i = 0; i < bullets.size(); i++)
{
Bullet b = (Bullet)bullets.get(i);
if(b.isVisible() == true)
{
b.move();
}
else
{
bullets.remove(i);
}
}
p.move();
for(int i = 0; i < baddies.length; i++)
{
if(p.x > 400)
{
baddies[i].move(p.getdx());
}
}
repaint();
}
public void paint(Graphics g)
{
super.paint(g);
Graphics2D g2d = (Graphics2D) g;
if(lost)
{
g2d.drawString("You Lose!", 300, 300);
}
if((p.getX() - 590) % 2400 == 0 || (p.getX() - 590) % 2400 == 1)
{
p.nx = 0;
}
if((p.getX() - 1790) % 2400 == 0 ||(p.getX() - 1790) % 2400 == 1)
{
p.nx2 = 0;
}
g2d.drawImage(img, 685-p.nx2, 0, null);
if(p.getX() >= 590)
{
g2d.drawImage(img, 685-p.nx, 0, null);
}
g2d.drawImage(p.getImage(), p.edge, p.getY(), null);
ArrayList<?> bullets = Player.getBullets();
for(int i = 0; i < bullets.size(); i++)
{
Bullet b = (Bullet)bullets.get(i);
g2d.drawImage(b.getImg(), b.getX(), b.getY(), null);
}
for(int i = 0; i < baddies.length; i++)
{
if(baddies[i].isAlive == true)
{
g2d.drawImage(baddies[i].getImg(), baddies[i].getX(), baddies[i].getY(), null);
}
}
g2d.setColor(Color.white);
g2d.drawString("Score: " + score, 0, 320);
g2d.drawString("Lives: " + lives, 80, 320);
}
public void checkCollisions()
{
Rectangle[] rect = new Rectangle[baddies.length];
for(int i = 0; i < baddies.length; i++)
{
Enemy e = (Enemy)baddies[i];
rect[i] = e.getBounds();
}
ArrayList<?> bullets = Player.getBullets();
for (int i = 0; i < bullets.size(); i++)
{
Bullet b = (Bullet) bullets.get(i);
Rectangle b1 = b.getBounds();
if (rect[i].intersects(b1) && baddies[i].isAlive())
{
score++;
baddies[i].isAlive = false;
baddies[i].isVisible = false;
bang.play();
}
Rectangle h = p.getBounds();
if (h.intersects(rect[i]))
{
if(baddies[i].isAlive() == true)
{
lives--;
if(lives < 0)
{
lost = true;
theme.stop();
System.exit(1);
}
}
}
}
}
private class ActionListener extends KeyAdapter
{
public void keyReleased(KeyEvent e)
{
p.keyReleased(e);
}
public void keyPressed(KeyEvent e)
{
p.keyPressed(e);
}
}
}
Enemy
package ShooterGame;
import java.awt.*;
import javax.swing.ImageIcon;
public class Enemy
{
int x, y;
Image img;
boolean isAlive = true;
boolean isVisible = true;
public Enemy(int startX, int startY, String location)
{
x = startX;
y = startY;
ImageIcon l = new ImageIcon(location);
img = l.getImage();
}
public Rectangle getBounds()
{
return new Rectangle(x, y, 60, 60);
}
public int getX()
{
return x;
}
public int getY()
{
return y;
}
public boolean isAlive()
{
return isAlive;
}
public boolean isVisible()
{
return isVisible;
}
public Image getImg()
{
return img;
}
public void move(int dx)
{
x = x - dx;
}
}
Bullet
package ShooterGame;
import java.applet.Applet;
import java.awt.*;
import javax.swing.ImageIcon;
import java.applet.AudioClip;
public class Bullet
{
int x, y;
Image img;
boolean visible;
public Bullet(int startX, int startY)
{
x = startX;
y = startY;
ImageIcon newBullet = new ImageIcon("images/bullet.gif");
img = newBullet.getImage();
visible = true;
}
public Rectangle getBounds()
{
return new Rectangle(x, y, 9, 5);
}
public int getX()
{
return x;
}
public int getY()
{
return y;
}
public Image getImg()
{
return img;
}
public boolean isVisible()
{
return visible;
}
public void move()
{
x = x + 2;
if(x > 700)
{
visible = false;
}
}
public void setVisible(boolean isVisible)
{
visible = isVisible;
}
}
Player
package ShooterGame;
import java.applet.Applet;
import java.applet.AudioClip;
import java.awt.*;
import java.awt.event.KeyEvent;
import java.util.ArrayList;
import javax.swing.ImageIcon;
public class Player
{
int x, dx, y, dy, nx2, nx, edge, ceiling;
Image player;
ImageIcon ib = new ImageIcon("images/player1back.gif");
ImageIcon i = new ImageIcon("images/playerstill.gif");
ImageIcon f = new ImageIcon("images/playerforward.gif");
ImageIcon up = new ImageIcon("images/playerup.gif");
ImageIcon down = new ImageIcon("images/playerdown.gif");
public AudioClip laser;
static ArrayList<Bullet> bullets;
public Player()
{laser = Applet.newAudioClip(getClass().getResource("laser.wav"));
player = ib.getImage();
x = 75;
nx = 0;
nx2 = 685;
y = 172;
edge = 150;
ceiling = 0;
bullets = new ArrayList<Bullet>();
}
public static ArrayList<Bullet> getBullets()
{
return bullets;
}
public void fire()
{
Bullet z = new Bullet((edge + 60), (y+17));
bullets.add(z);
}
public Rectangle getBounds()
{
return new Rectangle(edge, y, 43, 39);
}
public void move()
{
y = y + dy;
if(y < ceiling)
{
y = ceiling;
}
if(y > 290)
{
y = 290;
}
if(dx != -1)
{
if(edge + dx <= 151)
{
edge = edge + dx;
}
else
{
x = x + dx;
nx2 = nx2 + dx;
nx = nx + dx;
}
}
else
{
if(edge + dx > 0)
{
edge = edge + dx;
}
}
}
public int getX()
{
return x;
}
public int getdx()
{
return dx;
}
public int getY()
{
return y;
}
public Image getImage()
{
return player;
}
public void keyPressed(KeyEvent e)
{
int key = e.getKeyCode();
if(key == KeyEvent.VK_RIGHT)
{
dx = 2;
player = f.getImage();
}
if(key == KeyEvent.VK_UP)
{
dy = -1;
player = up.getImage();
}
if(key == KeyEvent.VK_DOWN)
{
dy = 1;
player = down.getImage();
}
if(key == KeyEvent.VK_SPACE)
{
fire();
laser.play();
}
}
public void keyReleased(KeyEvent e)
{
int key = e.getKeyCode();
if(key == KeyEvent.VK_RIGHT)
{
dx = 1;
player = ib.getImage();
}
if(key == KeyEvent.VK_UP)
{
dy = 0;
player = ib.getImage();
}
if(key == KeyEvent.VK_DOWN)
{
dy = 0;
player = ib.getImage();
}
}
}
Frame
package ShooterGame;
import javax.swing.*;
public class Frame
{
public AudioClip theme;
public Frame()
{
JFrame frame = new JFrame();
frame.add(new Board());
frame.setTitle("SideShooter");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(700,365);
frame.setVisible(true);
frame.setLocationRelativeTo(null);
}
public static void main(String[] args)
{
new Frame();
}
}

Ok, so the problem is the line mentioned in the other answer, but I believe it is that all the enemies may not be initialised before it checks collisions. Because you are making 10000 of them to start with, I think your action performed method may be checking collisions before they have all be created.
One thing to try could be to bring down the amount of enemies you have and see if it still keeps happening, try 100 or 1000, but this still won't fix the issue.
You really want to be change your game to run in it's own loop though, at the moment you are only checking collisions when the player performs an action. so if the player stops moving, no collision detection...
I would suggest that you find a book called 'Killer Game Programming in Java', there are free ebook version, and just read the first 2 chapters about making a game loop. The book is a bit old, but the basics of the loop are very good.
This question here also contains a very simple loop, and some suggestions in the comments about how to make it better.

The error is on the line
rect[i] = e.getBounds();
Are you not initializing the bounds of your Enemy class correctly? Alternatively, the Enemy you pulled out of the array could be null.

Drawing a line using a Mouse Motion Listener

I'm new at using actionListener and mouselistner. I want to track the Mouse movements and connect the dots as I go. So it will be one continuous line. I am using the MouseMotionListener every time I move the mouse across the screen and get a new set of points. I am not using mousePressed or mouseReleased.
Everytime I move the mouse, I can get every point of where my mouse's position is on my JPanel to show up on my results window, but in order to draw the line between two points, I'm not sure how to decipher between each different set of points so I can have a beginning and ending set of points to use for drawing a line? I checked through here and the API and I'm stuck.
I was asked to put more code and so I gave you my code.
I am basically creating a Jpane that tracks mouse movement when the Track Mouse button or Draw Track Radio button is pressed
These results will print out as (x,y) on the output screen
FYI: You can also draw circles once the Draw circles RadioButton is checked
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
public class MouseTest {
private JFrame frame;
private boolean tracking;
private boolean drawing;
private boolean connectdots;
private int xstart;
private int ystart;
private int xend;
private int y;
private int x;
private int yend;
private int borderWidth = 5;
String drawCircles = "Draw Circles";
String drawTrack = "Draw Track";
public static void main (String [] arg) {
MouseTest first = new MouseTest();
}//main
$
public MouseTest() {
tracking = false;
frame = new JFrame();
frame.setBounds(250,98,600,480);
frame.setTitle("Window number three");
Container cp = frame.getContentPane();
JButton track = new JButton("Track Mouse");
track.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
trackMouse();
}
});
JPanel top = new JPanel();
top.add(track);
cp.add(top,BorderLayout.NORTH);
MyPanel pane = new MyPanel();
cp.add(pane,BorderLayout.CENTER);
pane.addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
xstart = e.getX();
ystart = e.getY();
}
public void mouseReleased(MouseEvent e) {
xend = e.getX();
yend = e.getY();
if (xend < xstart) { int tmp = xstart; xstart = xend; xend = tmp; }
if (yend < ystart) { int tmp = ystart; ystart = yend; yend = tmp; }
frame.repaint();
}
});
pane.addMouseMotionListener(new MouseMotionAdapter() {
public void mouseMoved(MouseEvent e) {
if (tracking) {
x = e.getX();
y = e.getY();
msg("(" + x + ", " + y + ")");
}
}
});
JRadioButton circleButton = new JRadioButton(drawCircles);
circleButton.setMnemonic(KeyEvent.VK_B);
circleButton.setActionCommand(drawCircles);
circleButton.setSelected(false);
JRadioButton trackButton = new JRadioButton(drawTrack);
trackButton.setMnemonic(KeyEvent.VK_C);
ButtonGroup group = new ButtonGroup();
group.add(circleButton);
group.add(trackButton);
JPanel radioPanel = new JPanel(new GridLayout(2,0));
radioPanel.add(circleButton);
radioPanel.add(trackButton);
cp.add(radioPanel,BorderLayout.EAST);
drawing = false;
connectdots = false;
circleButton.addActionListener(new ActionListener() { //Set drawing to true when the button is clicked
public void actionPerformed(ActionEvent ae) {
tracking = !tracking;
drawCircles();
}
});
trackButton.addActionListener(new ActionListener() { //Set drawing to true when the button is clicked
public void actionPerformed(ActionEvent ae) {
drawing = false;
tracking = true;
connectDots();
}
});
frame.setVisible(true);
}//constructor
$
public void trackMouse() {
tracking = !tracking;
}//trackMouse
public void msg(String s) { //new method to simplify the system.out.print method
System.out.println(s);
}
public void drawCircles() {
drawing = true;
}//Allow Drawing of Circles
public void connectDots() {
connectdots = !connectdots;
}//Trying to use for connecting the mouse motion listener points when tracking
$
public class MyPanel extends JPanel {
ArrayList<Circle> circles = new ArrayList<Circle>();
public void paintComponent(Graphics g) {
int width = this.getWidth();
int height = this.getHeight();
msg("H = " + height + ", w = " + width);
g.setColor(Color.BLACK);
Circle c = new Circle(xstart, ystart);
circles.add(c);
if (drawing){
for(int k=0; k<circles.size(); k++){
circles.get(k).draw(g);
}
} // draw the circle
if (connectdots && tracking) { //trying to use for drawing the lines
g.drawLine(x,y,x,y);
}
for (int delta = 0; delta < borderWidth; delta++) {
g.drawRect(delta,delta,width-(2*delta),height-(2*delta));
}
if (xstart != xend || ystart != yend) {
int red = (int)(256*Math.random());
int green = (int)(256*Math.random());
int blue = (int)(256*Math.random());
g.setColor(new Color(red, green, blue));
msg("Colors are: " + red + " - " + green + " - " + blue );
msg("Drawing from: (" + xstart + ", " + ystart + ") to (" + xend + ", " + yend + ")");
msg("Width is " + (xend-xstart) + " - Height is " + (yend-ystart));
g.fillRect(xstart,ystart,xend-xstart,yend-ystart);
}
}
}
}
$
public class Circle {
// instance variables:
int radius; //random radius
int x, y; // coords of the center point
private Graphics g;
public Circle(int xIn, int yIn) {
radius = (int)(127*Math.random());
x = xIn;
y = yIn;
}
public void draw(Graphics g){
g.drawOval(x-radius, y-radius, radius, radius);
g.fillOval(x-radius, y-radius, radius, radius);
int red = (int)(256*Math.random());
int green = (int)(256*Math.random());
int blue = (int)(256*Math.random());
g.setColor(new Color(red, green, blue));
}
public int getX(int xstart) {
// TODO Auto-generated method stub
return x;
}
public int getY(int ystart) {
// TODO Auto-generated method stub
return y;
}
}

You just have to save x and y in some attribute for your class (like lastX and lastY.) When you get the event the second time, your first point coordinates are saved in your attributes and you can then draw your line. This new point has to be saved too to serve as your new lastX and lastY.
Even better: since you'll probably need to redraw your lines each frame (if you want a set of lines and not just a single line to be drawn each frame), use Point to save your coordinates and some kind of list like ArrayList. Save the full set of tracked points in an ArrayList<Point> and then draw each frame iterating over this list.

An example of an sscce:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
#SuppressWarnings("serial")
public class Foo3 extends JPanel {
private static final int PREF_W = 400;
private static final int PREF_H = PREF_W;
private boolean tracking = false;
private int x, y;
public Foo3() {
add(new JToggleButton(new AbstractAction("TrackMouse") {
public void actionPerformed(ActionEvent ae) {
trackMouse(ae);
}
}));
MyMouseAdapter myMA = new MyMouseAdapter();
addMouseMotionListener(myMA);
}
private void trackMouse(ActionEvent ae) {
JToggleButton toggleBtn = (JToggleButton) ae.getSource();
tracking = toggleBtn.isSelected();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
public void msg(String message) {
System.out.println(message);
}
private class MyMouseAdapter extends MouseAdapter {
#Override
public void mouseMoved(MouseEvent e) {
if (tracking) {
x = e.getX();
y = e.getY();
msg("(" + x + ", " + y + ")");
}
}
}
private static void createAndShowGui() {
Foo3 mainPanel = new Foo3();
JFrame frame = new JFrame("MouseMotion Eg");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
Edit: Example 2
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import javax.swing.*;
#SuppressWarnings("serial")
public class MouseTestHovercraft extends JPanel {
private static final int PREF_W = 600;
private static final int PREF_H = PREF_W;
private static final int MAX_CLR = 5;
private static final Color CURRENT_LIST_COLOR = new Color(190, 190, 255);
private List<Color> colors = new ArrayList<Color>();
private boolean tracking = false;
private List<Point> currentList = null;
private BufferedImage bufferedImage = new BufferedImage(PREF_W, PREF_H,
BufferedImage.TYPE_INT_ARGB);
private Random random = new Random();
public MouseTestHovercraft() {
for (int redIndex = 0; redIndex < MAX_CLR; redIndex++) {
int r = (redIndex * 256) / (MAX_CLR - 1);
r = (r == 256) ? 255 : r;
for (int greenIndex = 0; greenIndex < MAX_CLR; greenIndex++) {
int g = (greenIndex * 256) / (MAX_CLR - 1);
g = (g == 256) ? 255 : g;
for (int blueIndex = 0; blueIndex < MAX_CLR; blueIndex++) {
int b = (blueIndex * 256) / (MAX_CLR - 1);
b = (b == 256) ? 255 : b;
Color c = new Color(r, g, b);
colors.add(c);
}
}
}
add(new JToggleButton(new AbstractAction("TrackMouse") {
public void actionPerformed(ActionEvent ae) {
trackMouse(ae);
}
}));
add(new JButton(new AbstractAction("Clear Image") {
public void actionPerformed(ActionEvent e) {
bufferedImage = new BufferedImage(getWidth(), getHeight(),
BufferedImage.TYPE_INT_ARGB);
repaint();
}
}));
MyMouseAdapter myMA = new MyMouseAdapter();
addMouseListener(myMA);
addMouseMotionListener(myMA);
}
private void trackMouse(ActionEvent ae) {
JToggleButton toggleBtn = (JToggleButton) ae.getSource();
tracking = toggleBtn.isSelected();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
public void msg(String message) {
System.out.println(message);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(bufferedImage, 0, 0, null);
if (currentList != null) {
drawList(g, currentList, CURRENT_LIST_COLOR, 1f);
}
}
private void drawList(Graphics g, List<Point> ptList, Color color,
float strokeWidth) {
if (ptList.size() > 1) {
Graphics2D g2 = (Graphics2D) g.create();
g2.setColor(color);
g2.setStroke(new BasicStroke(strokeWidth));
for (int j = 0; j < ptList.size() - 1; j++) {
int x1 = ptList.get(j).x;
int y1 = ptList.get(j).y;
int x2 = ptList.get(j + 1).x;
int y2 = ptList.get(j + 1).y;
g2.drawLine(x1, y1, x2, y2);
}
g2.dispose();
}
}
private class MyMouseAdapter extends MouseAdapter {
#Override
public void mousePressed(MouseEvent e) {
if (tracking && e.getButton() == MouseEvent.BUTTON1) {
currentList = new ArrayList<Point>();
currentList.add(e.getPoint());
}
}
#Override
public void mouseReleased(MouseEvent e) {
if (tracking && e.getButton() == MouseEvent.BUTTON1) {
currentList.add(e.getPoint());
Graphics2D g2 = bufferedImage.createGraphics();
Color color = colors.get(random.nextInt(colors.size()));
drawList(g2, currentList, color, 3f);
currentList = null;
repaint();
}
}
#Override
public void mouseDragged(MouseEvent e) {
if (tracking && currentList != null) {
currentList.add(e.getPoint());
repaint();
}
}
}
private static void createAndShowGui() {
MouseTestHovercraft mainPanel = new MouseTestHovercraft();
JFrame frame = new JFrame("MouseMotion Eg");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.setResizable(false);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}

My Bouncing Ball Does Not Draw

I am having a problem getting my application to draw a Ball when i click on the frame.
I thought my code was correct, and I don't get any errors, but it still doesn't work.
I feel the problem is with the MouseListener implementation and that the application is not handling the MouseEvent properly.
import java.awt.*;
import java.awt.geom.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.*;
public class BouncingBallApp extends JFrame
{
public static void main(String[] args)
{
Container container;
BouncingBallApp bouncingBalls = new BouncingBallApp();
bouncingBalls.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
container = new Container();
BouncingBallPanel BBP = new BouncingBallPanel();
container.add(BBP);
bouncingBalls.addMouseListener(BBP);
//addMouseListener;
bouncingBalls.setBackground( Color.WHITE );
bouncingBalls.setSize(400,300);
bouncingBalls.setVisible( true );
}//end of main method
}//end of BouncingBallApp
class BouncingBallPanel extends JPanel implements MouseListener, Runnable
{
private Ball[] ballArray = new Ball[20];
private int ballCount = 0;
public void run()
{
for(int i = 0; i<ballArray.length; i++){
if(ballArray[i] != null){
ballArray[i].move();}}
repaint();
//delay(1);
}
public void mouseClicked(MouseEvent e)
{
ballArray[ballCount] = new Ball();
ballCount++;
if(ballCount == 1)
(new Thread(new BouncingBallPanel())).start();
}
//empty interface methods
public void mouseExited(MouseEvent e){}
public void mouseReleased(MouseEvent e){}
public void mouseEntered(MouseEvent e){}
public void mousePressed(MouseEvent e){}
public void paintComponent(Graphics g)
{
super.paintComponent( g );
Graphics2D g2d = (Graphics2D) g;
for(int i = 0; i<ballArray.length; i++)
{
if(ballArray[i] != null){
g2d.setColor(ballArray[i].getColor());
g2d.fill(new Ellipse2D.Double(ballArray[i].getX(),ballArray[i].getY(),ballArray
[i].getDiameter(),ballArray[i].getDiameter()));}
}//end of for loop
}
}//end of BouncingBallPanel
class Ball
{
private double x;
private double y;
private double deltaX;
private double deltaY;
private double diameter;
private Color color;
Random random = new Random();
public Ball()
{
x = random.nextInt(400);
y = random.nextInt(300);
deltaX = 2;
deltaY = 2;
diameter = 10;
color = new Color(random.nextInt(256),random.nextInt(256),random.nextInt(256));
}//end of constructor
public double getX(){
return x;}
public double getY(){
return y;}
public double getDiameter(){
return diameter;}
public Color getColor(){
return color;}
public void move()
{
x += deltaX;
y += deltaY;
if (x < 0) {
x = 0;
deltaX = -deltaX;}
else if (x > 400) {
x = 400;
deltaX = -deltaX;}
if (y < 0) {
y = 0;
deltaY = -deltaY;}
else if (y > 300) {
y = 300;
deltaY = -deltaY;}
}//end of method move
}//end of ball

3 Things
No size for container
You are not adding container
No loop to update graphics
The code below is working
import java.awt.*;
import java.awt.geom.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.*;
public class BouncingBallApp extends JFrame {
public static void main(String[] args) {
// Container container;
BouncingBallApp bouncingBalls = new BouncingBallApp();
bouncingBalls.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// container = new Container();
BouncingBallPanel BBP = new BouncingBallPanel();
// container.add(BBP);
bouncingBalls.addMouseListener(BBP);
// addMouseListener;
bouncingBalls.setBackground(Color.WHITE);
bouncingBalls.setSize(400, 300);
BBP.setSize(400, 300);
BBP.setLayout(null);
bouncingBalls.setContentPane(BBP);
/*
* JTextField jtf = new JTextField(); BBP.add(jtf); jtf.setSize(100,
* 20);
*/
bouncingBalls.setVisible(true);
}// end of main method
}// end of BouncingBallApp
class BouncingBallPanel extends JPanel implements MouseListener {
private Ball[] ballArray = new Ball[20];
private int ballCount = 0;
public void mouseClicked(MouseEvent e) {
ballArray[ballCount] = new Ball();
ballCount++;
if (ballCount == 1) {
final Runnable updateGraphics = new Runnable() {
public void run() {
for (int i = 0; i < ballArray.length; i++) {
if (ballArray[i] != null) {
ballArray[i].move();
}
}
repaint();
}
};
Runnable animation = new Runnable() {
public void run() {
while (true) {
try {
EventQueue.invokeLater(updateGraphics);
Thread.sleep(100);
} catch (InterruptedException e) {
return;
}
}
}
};
new Thread(animation).start();
}
}
// empty interface methods
public void mouseExited(MouseEvent e) {
}
public void mouseReleased(MouseEvent e) {
}
public void mouseEntered(MouseEvent e) {
}
public void mousePressed(MouseEvent e) {
}
public void paintComponent(Graphics g) {
// super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
for (int i = 0; i < ballArray.length; i++) { if (ballArray[i] !=
null) { System.out.println(" ball " + i + " , " +
ballArray[i].getColor() + " , " + ballArray[i].getX() + " , " +
ballArray[i].getY() + " , " + ballArray[i].getDiameter());
g2d.setColor(ballArray[i].getColor());
g2d.fillRect((int)ballArray[i].getX(), (int)ballArray[i].getY(),
(int)ballArray[i].getDiameter(), (int)ballArray[i].getDiameter()); }
}// end of for loop
}
}// end of BouncingBallPanel
class Ball {
private double x;
private double y;
private double deltaX;
private double deltaY;
private double diameter;
private Color color;
Random random = new Random();
public Ball() {
x = random.nextInt(400);
y = random.nextInt(300);
deltaX = 2;
deltaY = 2;
diameter = 10;
color = new Color(random.nextInt(256), random.nextInt(256), random.nextInt(256));
}// end of constructor
public double getX() {
return x;
}
public double getY() {
return y;
}
public double getDiameter() {
return diameter;
}
public Color getColor() {
return color;
}
public void move() {
x += deltaX;
y += deltaY;
if (x < 0) {
x = 0;
deltaX = -deltaX;
}
else if (x > 400) {
x = 400;
deltaX = -deltaX;
}
if (y < 0) {
y = 0;
deltaY = -deltaY;
}
else if (y > 300) {
y = 300;
deltaY = -deltaY;
}
}// end of method move
}// end of ball