Develop Reference

Adding a JButton to a class extended by JPanel is not displaying a button

When I use normal JPanel initialized inside main instead of extended class. The button is added to a panel without problem and after launch is displayed in a center of a frame (default layout).
I would like to be able to add buttons inside an extended class. This problem occurs in Screen class aswell, where I need a Play Again button or Next Level button. The Screen is class extended by a JPanel too and JButtons are initialized inside the constructor aswell.
I'm not sure if the wrong part is in way of adding the components or in writing a code for a JPanel.
Here is the code:
Main:
public static void main(String[] args) {
// window - class JFrame
theFrame = new JFrame("Brick Breaker");
// game panel initialization
GamePanel gamePanel = new GamePanel(1);
theFrame.getContentPane().add(gamePanel);
// base settings
theFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
theFrame.setLocationRelativeTo(null);
theFrame.setResizable(false);
theFrame.setSize(WIDTH, HEIGHT);
theFrame.setVisible(true);
}
GamePanel Class:
public class GamePanel extends JPanel {
// Fields
boolean running;
boolean clicked = false;
private int rows = 8, colms = 11, N = rows * colms, level; // numbers of rows and columns
private int colmsC, rowsC;
private BufferedImage image;
private Graphics2D g;
private MyMouseMotionListener theMouseListener;
private MouseListener mouseListener;
private int counter = 0;
// entities
Ball theBall;
Paddle thePaddle;
Bricle[] theBricks;
Screen finalScreen;
public GamePanel(int level) {
// buttons
JButton pause = new JButton(" P ");
add(pause);
this.level = level;
init(level);
}
public void init(int level) {
// level logic
this.rowsC = level + rows;
this.colmsC = level + colms;
int count = rowsC * colmsC;
thePaddle = new Paddle();
theBall = new Ball();
theBall.setY(thePaddle.YPOS - thePaddle.getHeight() + 2);
theBall.setX(thePaddle.getX() + thePaddle.getWidth() / 2 - 5);
theBricks = new Bricle[count];
theMouseListener = new MyMouseMotionListener();
addMouseMotionListener(theMouseListener);
mouseListener = new MyMouseListener();
addMouseListener(mouseListener);
// make a canvas
image = new BufferedImage(BBMain.WIDTH, BBMain.HEIGHT, BufferedImage.TYPE_INT_RGB);
g = (Graphics2D) image.getGraphics();
g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
// specific Bricks initialized
int k = 0;
for (int row = 0; row < rowsC; row++) {
for (int col = 0; col < colmsC; col++) {
theBricks[k] = new Bricle(row, col);
k++;
}
}
running = true;
}
public void playGame() {
while (running) {
//update
if (clicked) {
update();
}
// draw
draw();
// display
repaint();
// sleep
try {
Thread.sleep(20);
} catch (Exception e) {
e.printStackTrace();
}
}
}
// update loop ( like playGame )
public void update() {
// ball moving
checkCollisions();
theBall.update();
}
public void draw() {
// background
g.setColor(Color.WHITE);
g.fillRect(0,0, BBMain.WIDTH, BBMain.HEIGHT-20);
// the bricks
int k = 0;
for (int row = 0; row < rowsC; row++) {
for (int col = 0; col < colmsC; col++) {
theBricks[k].draw(g, row, col);
k++;
}
}
// the ball and the paddle
theBall.draw(g);
thePaddle.draw(g);
// counter
String countString = new Integer(this.counter).toString();
g.drawString(countString, 20, 20);
// WIN / LOOSE SCREEN
if (this.counter == this.N * 20) {
win();
}
if (theBall.getRect().getY() + theBall.getRect().getHeight() >= BBMain.HEIGHT) {
loose();
}
}
public void paintComponent(Graphics g) {
// retype
Graphics2D g2 = (Graphics2D) g;
// draw image
g2.drawImage(image, 0, 0, BBMain.WIDTH, BBMain.HEIGHT, null);
// dispose
g2.dispose();
}
public void pause() {
this.running = false;
finalScreen = new Screen(this.level, counter);
finalScreen.draw(g,"GAME PAUSED");
}
public void win() {
this.running = false;
finalScreen = new Screen(this.level, counter);
finalScreen.draw(g,"YOU WIN");
}
public void loose () {
this.running = false;
finalScreen = new Screen(this.level, counter);
finalScreen.draw(g,"YOU LOOSE");
}
public void addScore() {
this.counter += 20;
theBall.setDY(theBall.getDY() - 0.001);
}
// Mouse Listeners
private class MyMouseListener implements MouseListener {
#Override
public void mouseClicked(MouseEvent e) {
clicked = true;
}
#Override
public void mousePressed(MouseEvent e) {
}
#Override
public void mouseReleased(MouseEvent e) {
}
#Override
public void mouseEntered(MouseEvent e) {
}
#Override
public void mouseExited(MouseEvent e) {
}
}
private class MyMouseMotionListener implements MouseMotionListener {
#Override
public void mouseDragged(MouseEvent e) {
}
#Override
public void mouseMoved(MouseEvent e) {
if (clicked)
thePaddle.mouseMoved(e.getX());
}
}
}

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.

Drawing on JPanel and broadcast it to multiple client

I have Multi-user Chat-room with shared whiteboard application where I used a Jpanel to draw in a specific client and then broadcast over server to other clients(through Java Socket Programming).
My issue is that I wanted to make the function of draw work real-time as in as soon as a drawing is done on one client's JPanel it should be visible to the other clients. I wrote the function on mouseReleased event of JPanel, but it is visible to the other clients only after a mouseReleased event is fired on that client's JPanel.
Can anyone suggest something by which I can make the action better(real-time)?
#Override
public void mouseReleased(MouseEvent e) {
lineObject = new LineMessage();
lineObject.setImageMessage(DrawPanel.linelist);
ChatApplication_Client.Action_Paint(lineObject);
}
ChatApplication_Client.java
public void run(){
System.out.println("Listening for messages from server . . . ");
try{
while(!receivingdone){
object = myInputStream.readObject();
if(object instanceof LineMessage)
{
lineObject = (LineMessage) object;
WhiteBoardMessageReceive(lineObject);
}
}
}
// This method responsible for re-painting and broadcasting at client's end
private void WhiteBoardMessageReceive(LineMessage lineObject)
{
ArrayList<Line> linelist = (ArrayList)
lineObject.getImageMessage();
ChatClient_GUI.TA_ChatWindow.append(lineObject.Name+": "
+lineObject.Text + "\n" + "At ["
+DateUtils.now()+ "] " + "\n");
drawPanel.drawit(linelist);
}
//The Following method is called from the gui on mouseReleased event
public static void Action_Paint(LineMessage lineObject)
{
try
{
myOutputStream.reset();
myOutputStream.writeObject(lineObject);
myOutputStream.flush();
}
catch(Exception e)
{
System.out.println(e.getMessage());
}
}
LineMessage.java
class LineMessage implements Serializable
{
ArrayList<Line> message;
Line line = new Line();
String Name =line.getName() ;
String Text ;
public void setImageMessage(Object message) {
this.message = (ArrayList) message;
}
public Object getImageMessage() {
return message;
}
}
class Line extends ChatMessage implements Serializable {
int startx, starty, endx, endy;
public Line() {
}
public Line(int sx, int sy, int ex, int ey)
{
setStartX(sx);
setStartY(sy);
setEndX(ex);
setEndY(ey);
}
public void setStartX(int sx) {
startx = sx;
}
public void setStartY(int sy) {
starty = sy;
}
public void setEndX(int ex) {
endx = ex;
}
public void setEndY(int ey) {
endy = ey;
}
public int getStartX() {
return startx;
}
public int getStartY() {
return starty;
}
public int getEndX() {
return endx;
}
public int getEndY() {
return endy;
}
}

List<Point> pointList = new ArrayList<>();
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(300, 500);
JPanel panel = new JPanel(){
#Override
public void paint(Graphics g) {
super.paint(g);
g.setColor(Color.WHITE);
g.fillRect(0, 0, getWidth(), getHeight());
g.setColor(Color.BLACK);
Point l = null;
for(Point p : pointList){
if(l != null && p != null)
g.drawLine(l.x, l.y, p.x, p.y);
l = p;
}
}
};
frame.setContentPane(panel);
panel.addMouseMotionListener(new MouseMotionListener() {
boolean isDrawing = false;
#Override
public void mouseDragged(MouseEvent e) {
pointList.add(e.getPoint());
isDrawing = true;
panel.repaint();
}
#Override
public void mouseMoved(MouseEvent e) {
if(isDrawing)
pointList.add(null); //null is a placeholder to mean line is finished
isDrawing = false;
}
});
frame.setVisible(true);

Drawing shapes in JPanel over an image

I need to draw shapes (circle or free line) over an image that is shown in a JLabel of a JPanel.
I based my code on the questions How to draw thin line with no gap while dragging the cursor? and Draw a circle using 2 mouse clicks.
The code is bellow. The problem is that when I start drawing the image disappears and only reappears after I stop.
If I comment the line super.paintComponent(g); that doesnt happen but when I draw the circle it maintains a path of the previous positions.
public static void main(String args[]) {
try {
URL url = new URL("http://www.senhoritatours.com/wp-content/uploads/2014/05/Porto-.jpg");
backgroundImage = ImageIO.read(url);
} catch (Exception e) {
e.printStackTrace();
}
loadAnnotation();
loadBackground();
JFrame f;
f = new JFrame();
f.setLayout(new BorderLayout());
f.add(mp);
f.pack();
f.setVisible(true);
}
/* Layer 0:
* Load background picture */
public static void loadBackground() {
JLabel lbImg = new JLabel();
lbImg.setBounds(0, 0, new ImageIcon(backgroundImage).getIconWidth(), new ImageIcon(backgroundImage).getIconHeight());
lbImg.setIcon(new ImageIcon(backgroundImage));
mp = new JPanel(new BorderLayout());
btnCircle.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
if(btnCircle.isEnabled())
{
btnCircle.setEnabled(false);
btnLine.setEnabled(true);
}
}
});
btnLine.setEnabled(true);
btnCircle.setEnabled(false);
btnLine.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
if(btnLine.isEnabled())
{
btnLine.setEnabled(false);
btnCircle.setEnabled(true);
}
}
});
mp.add(btnCircle);
mp.add(btnLine);
mp.add(lbImg);
mp.add(p);
}
/* Layer 1:
* Annotation: Draw on top of background picture anything! */
public static void loadAnnotation() {
p = new JPanel() {
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
g2.setColor(Color.RED);
if (_bufImage == null) {
int w = this.getWidth();
int h = this.getHeight();
_bufImage = new BufferedImage(1024,600, BufferedImage.TRANSLUCENT);
Graphics2D gc = _bufImage.createGraphics();
}
g2.drawImage(_bufImage, null, 0, 0);
if (_state == State.DRAGGING) {
if (!btnLine.isEnabled())
{
g.drawLine(_start.x, _start.y, _end.x , _end.y);
}
}
if (!btnCircle.isEnabled())
{
g.drawOval(x, y, width, height);
}
}
public Dimension getPreferredSize() {
return new Dimension(1024, 600);
}
};
p.setLayout(new OverlayLayout(p));
p.addMouseListener(new MouseListener() {
#Override
public void mouseClicked(MouseEvent me) {
}
#Override
public void mousePressed(MouseEvent me) {
last = me.getPoint();
dragging = isInsideEllipse(last);
if (!dragging) {
x = last.x;
y = last.y;
width = 0;
height = 0;
}
p.repaint();
}
#Override
public void mouseReleased(MouseEvent me) {
//_state = State.IDLE;
last = null;
dragging = false;
_state = State.IDLE;
p.repaint();
}
#Override
public void mouseEntered(MouseEvent me) {
}
#Override
public void mouseExited(MouseEvent me) {
}
});
p.addMouseMotionListener(new MouseMotionListener() {
#Override
public void mouseDragged(MouseEvent me) {
if(!btnLine.isEnabled())
{
_state = State.DRAGGING;
_end = me.getPoint();
if (_state == State.DRAGGING) {
Graphics2D g2 = _bufImage.createGraphics();
g2.setColor(Color.red);
g2.setStroke(new BasicStroke(2));
g2.drawLine(_start.x, _start.y, _end.x, _end.y);
p.repaint();
//
}
_start = _end;
}
else
{
int dx = me.getX() - last.x;
int dy = me.getY() - last.y;
if (dragging) {
x += dx;
y += dy;
} else {
width += dx;
height += dy;
}
last = me.getPoint();
p.repaint();
}
}
#Override
public void mouseMoved(MouseEvent me) {
//System.out.println("move");
_start = me.getPoint();
}
});
}

Either
Display the image in the same paintComponent method that you're doing your drawing in, via Graphics#drawImage(...). You would call this immediately after the super.paintComponent(g) call.
Or do your drawing in the paintComponent(...) method of your JLabel, the one displaying the image.
For example:
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.*;
#SuppressWarnings("serial")
public class DrawingPanel extends JPanel {
private final static String PATH = "https://upload.wikimedia.org/wikipedia/commons/"
+ "thumb/7/7c/Thomas_Hicks_-_Leopold_Grozelier_-_Presidential_Candidate_"
+ "Abraham_Lincoln_1860_-_cropped_to_lithographic_plate.jpg/"
+ "463px-Thomas_Hicks_-_Leopold_Grozelier_-_Presidential_Candidate_"
+ "Abraham_Lincoln_1860_-_cropped_to_lithographic_plate.jpg";
private static final Color DRAWING_COLOR = new Color(255, 100, 200);
private static final Color FINAL_DRAWING_COLOR = Color.red;
private BufferedImage backgroundImg;
private Point startPt = null;
private Point endPt = null;
private Point currentPt = null;
private int prefW;
private int prefH;
public DrawingPanel() throws IOException {
URL imgUrl = new URL(PATH);
BufferedImage bImg = ImageIO.read(imgUrl);
prefW = bImg.getWidth();
prefH = bImg.getHeight();
backgroundImg = new BufferedImage(prefW, prefH,
BufferedImage.TYPE_INT_ARGB);
Graphics g = backgroundImg.getGraphics();
g.drawImage(bImg, 0, 0, this);
g.dispose();
MyMouseAdapter myMouseAdapter = new MyMouseAdapter();
addMouseMotionListener(myMouseAdapter);
addMouseListener(myMouseAdapter);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (backgroundImg != null) {
g.drawImage(backgroundImg, 0, 0, this);
}
if (startPt != null && currentPt != null) {
g.setColor(DRAWING_COLOR);
int x = Math.min(startPt.x, currentPt.x);
int y = Math.min(startPt.y, currentPt.y);
int width = Math.abs(startPt.x - currentPt.x);
int height = Math.abs(startPt.y - currentPt.y);
g.drawRect(x, y, width, height);
}
}
#Override
public Dimension getPreferredSize() {
return new Dimension(prefW, prefH);
}
public void drawToBackground() {
Graphics g = backgroundImg.getGraphics();
g.setColor(FINAL_DRAWING_COLOR);
int x = Math.min(startPt.x, endPt.x);
int y = Math.min(startPt.y, endPt.y);
int width = Math.abs(startPt.x - endPt.x);
int height = Math.abs(startPt.y - endPt.y);
g.drawRect(x, y, width, height);
g.dispose();
startPt = null;
repaint();
}
private class MyMouseAdapter extends MouseAdapter {
#Override
public void mouseDragged(MouseEvent mEvt) {
currentPt = mEvt.getPoint();
DrawingPanel.this.repaint();
}
#Override
public void mouseReleased(MouseEvent mEvt) {
endPt = mEvt.getPoint();
currentPt = null;
drawToBackground();
}
#Override
public void mousePressed(MouseEvent mEvt) {
startPt = mEvt.getPoint();
}
}
private static void createAndShowGui() {
DrawingPanel mainPanel = null;
try {
mainPanel = new DrawingPanel();
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
JFrame frame = new JFrame("Drawing Panel");
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();
}
});
}
}

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.