javaswinganimationgraphicsgame-physics
Why does the height of the rectangles jump vary?
Why does the height of the rectangle's jump vary? It seems to go in a cycle. First it jumps low then it doesn't jump at all then it jumps high then it doesn't jump at all. i can't figure out why as the same code is used and it is triggered by the same event.
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.KeyEvent;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
@SuppressWarnings("serial")
class Game extends JPanel{
Square square = new Square(this);
Ground ground = new Ground (this);
public Game() {
addKeyListener(new KeyListener() {
@Override
public void keyTyped(KeyEvent e) {
}
@Override
public void keyReleased(KeyEvent e) {
square.keyReleased(e);
}
@Override
public void keyPressed(KeyEvent e) {
square.keyPressed(e);
}
});
setFocusable(true);
}
public static void main(String[] args) throws InterruptedException {
JFrame frame = new JFrame("My Mario");
Game game = new Game();
frame.add(game);
frame.setSize(600, 700);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
while (true) {
game.move();
game.repaint();
Thread.sleep(30);
}
}
private void move() {
square.move();
}
@Override
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
square.paint(g2d);
ground.paint(g2d);
}
}
public class Square {
Square square;
int x,xa;
static int y;
int ya;
private Game game;
public static int fistX,fistY;
static int d = 60;
int wide;
boolean onGround;
public Square(Game game) {
this.game = game;
x = 100;
y = 631;
xa = 0;
ya = 0;
onGround = false;
wide = game.getWidth();
}
public void move() {
if (x + xa > 0 && x + xa < game.getWidth()-30)
x = x + xa;
if (y + ya > 0 && y + ya < game.getHeight()-60){
for(int i=12; i< 0; i--);
ya+=10;
y = y + ya;
}
if ( collision() ) {
y-=10;
onGround = true;
}
Square.y+=10;
}
public void paint(Graphics2D g) {
g.setColor(Color.RED);
g.fillRoundRect(x, y-d, 30, d, 10, 10);
}
private boolean collision() {
return game.ground.getBounds().intersects(getBounds());
}
public Rectangle getBounds() {
return new Rectangle(x, y, 30, 60);
}
public void keyReleased(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_LEFT)
xa=0;
if (e.getKeyCode() == KeyEvent.VK_RIGHT)
xa=0;
if(e.getKeyCode() == KeyEvent.VK_DOWN)
d = 60;
if(e.getKeyCode() == KeyEvent.VK_UP);
}
public void keyPressed(KeyEvent e) {
// TODO Auto-generated method stub
if (e.getKeyCode() == KeyEvent.VK_LEFT)
xa = xa -3;
if (e.getKeyCode() == KeyEvent.VK_RIGHT)
xa = xa + 3;
if(e.getKeyCode() == KeyEvent.VK_DOWN)
d = 30;
if(e.getKeyCode() == KeyEvent.VK_UP)
ya -= 60;
}
}
class Ground {
int y,x,h,w;
public Ground(Game game){
x = 0;
y = game.getHeight()-30;
w = game.getWidth();
h = 30;
}
public void paint(Graphics2D g){
g.setColor(Color.BLACK);
g.fillRect(0, 700, 99999999, 30);
}
public Rectangle getBounds() {
return new Rectangle(0, 700, 99999999, 30);
}
}
Solution
- Don't block the Event Dispatching Thread any way, it will prevent the EDT from processing repaint requests (and other events) which will make it look like your program has crashed. Have a read of Concurrency in Swing for more information.
- Only modify the UI from the EDT, NEVER from any other thread, this includes creating UI elements
- Favor key bindings over
KeyListeners, they are more capable of resolving focus issues amongst other things. Have a read of How to Use Key Bindings for more details - Favor overriding
paintComponentrather thenpaint. Paint does a lot of important work which you should avoid messing with if you can. Apart from any thing elsepaintComponentis going to be included in the double buffering of the component where aspaintisn't (assuper.paintsets it up) - Avoid using
staticstate variables where possible - I don't know if this was deliberate or not, but,
for (int i = 12; i < 0; i--);isn't going to achive anything, as the semi colen at the end means, do nothing for a count of 1 - Personally, try not to use absolute values for things like width and height, which is actually reliant on parent container. You should also, where possible, provide sizing hints to allow the parent container to make better decisions on how much space it actually needs
UPDATED
Fixed bug in my movement code :P
I had a look at your collision detection code (in move) and, frankly, couldn't make heads or tails of it. I corrected it as well as changed in the way the paint method works so that x,y is always the top, left corner
public class TestGame {
public static void main(String[] args) throws InterruptedException {
new TestGame();
}
public TestGame() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException ex) {
} catch (InstantiationException ex) {
} catch (IllegalAccessException ex) {
} catch (UnsupportedLookAndFeelException ex) {
}
Game game = new Game();
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(game);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class GameThread extends Thread {
private Game game;
public GameThread(Game game) {
setDaemon(false);
this.game = game;
}
@Override
public void run() {
while (true) {
game.move();
try {
long startedAt = System.currentTimeMillis();
SwingUtilities.invokeAndWait(new Runnable() {
@Override
public void run() {
game.repaint();
}
});
long completedAt = System.currentTimeMillis();
long sleepFor = 30 - (completedAt - startedAt);
if (sleepFor < 0) {
sleepFor = 30;
}
Thread.sleep(sleepFor);
} catch (Exception exp) {
exp.printStackTrace();
}
}
}
}
public class Game extends JPanel {
Square square = new Square(this);
Ground ground = new Ground(this);
public Game() {
// addKeyListener(new KeyListener() {
// @Override
// public void keyTyped(KeyEvent e) {
// }
//
// @Override
// public void keyReleased(KeyEvent e) {
// square.keyReleased(e);
// }
//
// @Override
// public void keyPressed(KeyEvent e) {
// square.keyPressed(e);
// }
// });
setFocusable(true);
InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap am = getActionMap();
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0, false), "press-left");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0, false), "press-right");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0, false), "press-down");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0, false), "press-up");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0, true), "release-left");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0, true), "release-right");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0, true), "release-down");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0, true), "release-up");
am.put("press-left", new PressLeftAction(square));
am.put("press-right", new PressRightAction(square));
am.put("press-down", new PressDownAction(square));
am.put("press-up", new PressUpAction(square));
am.put("release-left", new ReleaseLeftAction(square));
am.put("release-right", new ReleaseRightAction(square));
am.put("release-down", new ReleaseDownAction(square));
am.put("release-up", new ReleaseUpAction(square));
new GameThread(this).start();
// public void keyReleased(KeyEvent e) {
//
//
//
// if (e.getKeyCode() == KeyEvent.VK_LEFT) {
// xa = 0;
// }
//
// if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
// xa = 0;
// }
// if (e.getKeyCode() == KeyEvent.VK_DOWN) {
// d = 60;
// }
//
// if (e.getKeyCode() == KeyEvent.VK_UP);
// }
//
// public void keyPressed(KeyEvent e) {
//// TODO Auto-generated method stub
// if (e.getKeyCode() == KeyEvent.VK_LEFT) {
// xa = xa - 3;
// }
//
// if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
// xa = xa + 3;
// }
//
// if (e.getKeyCode() == KeyEvent.VK_DOWN) {
// d = 30;
// }
//
// if (e.getKeyCode() == KeyEvent.VK_UP) {
// ya -= 60;
// }
//
//
//
//
//
// }
}
public void move() {
square.move();
}
@Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
// Don't override paint, use paintComponent instead
// @Override
// public void paint(Graphics g) {
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
square.paint(g2d);
ground.paint(g2d);
g2d.dispose();
}
}
public class Square {
Square square;
private int x, xa;
// static int y;
private int y;
private int ya;
private Game game;
// public static int fistX, fistY;
private int fistX, fistY;
// static int d = 60;
private int d = 60;
private int wide;
private boolean onGround;
public Square(Game game) {
this.game = game;
x = 100;
y = 100;
xa = 0;
ya = 0;
onGround = false;
wide = game.getWidth();
}
public void move() {
y += ya;
x += xa;
if (x < 0) {
x = 0;
} else if (x + 30 > game.getWidth()) {
x = game.getWidth() - 30;
}
if (y < 0) {
y = 0;
} else if (collision()) {
onGround = true;
y = game.ground.getBounds().y - d;
}
// if (x + xa > 0 && x + xa < game.getWidth() - 30) {
// x = x + xa;
// }
//
// if (y + ya > 0 && y + ya < game.getHeight() - 60) {
// // This was never going to do anything, look at the
// // end of the line...the `;` is going to prevent the
// // statemt ya += 10 from begin called within the loop
//// for (int i = 12; i < 0; i--);
// for (int i = 12; i < 0; i--) {
// ya += 10;
// }
// y = y + ya;
// }
// if (collision()) {
// y -= 10;
// onGround = true;
//
// }
//
// y += 10;
}
public void paint(Graphics2D g) {
g.setColor(Color.RED);
System.out.println(x + "x" + (y - d));
g.fillRoundRect(x, y, 30, d, 10, 10);
}
private boolean collision() {
return game.ground.getBounds().intersects(getBounds());
}
public Rectangle getBounds() {
return new Rectangle(x, y, 30, 60);
}
}
public class Ground {
private Game game;
public Ground(Game game) {
this.game = game;
}
public void paint(Graphics2D g) {
g.setColor(Color.BLACK);
g.fillRect(0, game.getHeight() - 30, game.getWidth(), 30);
}
public Rectangle getBounds() {
return new Rectangle(0, game.getHeight() - 30, game.getWidth(), 30);
}
}
public abstract class AbstractSquareAction extends AbstractAction {
private Square square;
public AbstractSquareAction(Square square) {
this.square = square;
}
public Square getSquare() {
return square;
}
}
public class PressLeftAction extends AbstractSquareAction {
public PressLeftAction(Square square) {
super(square);
}
@Override
public void actionPerformed(ActionEvent e) {
getSquare().xa = -3;
System.out.println("pressLeft");
}
}
public class PressRightAction extends AbstractSquareAction {
public PressRightAction(Square square) {
super(square);
}
@Override
public void actionPerformed(ActionEvent e) {
getSquare().xa = 3;
}
}
public class PressDownAction extends AbstractSquareAction {
public PressDownAction(Square square) {
super(square);
}
@Override
public void actionPerformed(ActionEvent e) {
getSquare().ya = 30;
}
}
public class PressUpAction extends AbstractSquareAction {
public PressUpAction(Square square) {
super(square);
}
@Override
public void actionPerformed(ActionEvent e) {
getSquare().ya -= 30;
}
}
public class ReleaseLeftAction extends AbstractSquareAction {
public ReleaseLeftAction(Square square) {
super(square);
}
@Override
public void actionPerformed(ActionEvent e) {
getSquare().xa = 0;
}
}
public class ReleaseRightAction extends AbstractSquareAction {
public ReleaseRightAction(Square square) {
super(square);
}
@Override
public void actionPerformed(ActionEvent e) {
getSquare().xa = 0;
}
}
public class ReleaseDownAction extends AbstractSquareAction {
public ReleaseDownAction(Square square) {
super(square);
}
@Override
public void actionPerformed(ActionEvent e) {
getSquare().ya = 0;
}
}
public class ReleaseUpAction extends AbstractSquareAction {
public ReleaseUpAction(Square square) {
super(square);
}
@Override
public void actionPerformed(ActionEvent e) {
getSquare().ya = 0;
}
}
}
- How do I find where JDK is installed on my windows machine?
- CORS in Spring Security (Spring Boot 3)
- Illegal base64url character: ' ' when getting claims/decode from token Java JWT Spring Boot
- Java example of using ExecutorService and PipedReader/PipedWriter (or PipedInputStream/PipedOutputStream) for consumer-producer
- Why Joda DateTime gives different result than Java Date?
- Why am I getting "time limit exceeded" error in binary tree level order traversal problem in leetcode?
- do while loop to for each or for loop
- Switch Between 3 Tabs Using Selenium WebDriver with Java
- Lombok added but getters and setters not recognized in Intellij IDEA
- How do I avoid checking for nulls in Java?
- How to get all week dates for given date java
- IntelliJ IDEA stucks at "collecting data" while debug
- Disconnected from the target VM, address: '127.0.0.1:51928', transport: 'socket'
- UnsupportedOperationException when upgrading from Java 17 to Java 21
- Is there a way to get user's UID on Linux machine using java?
- Environment variable to control java.io.tmpdir?
- Why does my file have race conditions, even though I used StandardOpenOption.SYNC?
- JRuby-1.7.19 UDPSocket "initialize: name or service not known" while scanning IP range
- how to debug spring application with gradle
- Could not resolve all files for configuration ':app:androidJdkImage
- I do not understand why the value of smallCountLoopCount changes from 0 to 1 in the code provided. I expect it to remain at 0
- How can I emulate non-blocking i/o in Java using threads
- H2 in Tomcat SqlException locked by another process when embedded mode
- checking java date with postgresql timestamp without timezone
- Read in different data types from file
- Java, sorting analysis. Heapsort, Quicksort1, Quicksort2, Mergesort, given a blackbox
- How to get the YEAR for week of year for a date?
- What's the difference between Instant and LocalDateTime?
- Problems when a non-generic method overrides a generic method
- Binary search for first occurrence of k