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POFlickering images in JPanel
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copied!<p>I have created a game which paints images to a JPanel. This runs with a JTimer which executes every 14 milliseconds to move the background, moves obstacles and moves the player (helicopter). I get flickering of the background and of the obstacles occasionally, and it does not run particularly smoothly. Is there a way I can get around this? Do I need to use threads and animate in a different class? I also used double buffering, but then I found out that JPanels are double buffered anyway, so I removed it.</p> <p>Here is the code from the Panel class.</p> <pre><code>class ImagePanel extends JPanel implements KeyListener, MouseListener, MouseMotionListener { /** * */ private static final long serialVersionUID = -6096603231469523786L; Plane o1 = new Plane(); Tank o2 = new Tank(); ArrayList<Plane> planeArray; ArrayList<Tank> tankArray; ArrayList<Missile> missileArray; int bgx; int bgxTwo; int time; int y; int score; int obsNum; int obsNum2; int planeSpeed; int missileSpeed; int count; boolean holding; boolean gameOver; boolean startscreen; boolean shooting; boolean obsOne = false; boolean obsTwo = false; Color colorone = Color.WHITE; Color colortwo = Color.WHITE; Color restartColor = Color.white; Color menuColor = Color.white; Color bulletColor = Color.white; Font f1; Font f2; Font f3; String version = "Get To The Chopper Beta 1.2"; int level = 1; java.util.Timer movementtimer; TimerTask task; java.util.Timer obstacletimer; TimerTask taskTwo; private Image image; private Image imageTwo; private Image chopper; private Image chopper2; private Image tank; private Image plane; private Image missile; private Image explosion; BufferedImage bufferedImage; Graphics buffer; java.net.URL bgurl; java.net.URL curl; java.net.URL c2url; java.net.URL turl; java.net.URL purl; java.net.URL murl; java.net.URL eurl; // ///////// CONSTRUCTOR SETS NON-CHANGABLE VARIABLES //////////////// public ImagePanel() { setFocusable(true); addKeyListener(this); addMouseListener(this); addMouseMotionListener(this); f1 = new Font("Helvetica", Font.BOLD, 10); f2 = new Font("Helvetica", Font.PLAIN, 30); f3 = new Font("Helvetica", Font.PLAIN, 25); startscreen = true; getImages(); planeArray = new ArrayList<Plane>(); tankArray = new ArrayList<Tank>(); missileArray = new ArrayList<Missile>(); repaint(); } public void getImages() { bgurl = getClass().getResource("images/background.png"); switch (level) { case (1): bgurl = getClass().getResource("images/grassbackground.png"); bulletColor = Color.black; break; case (2): bgurl = getClass().getResource("images/snowbackground.png"); bulletColor = Color.red; break; } curl = getClass().getResource("images/heli.png"); c2url = getClass().getResource("images/heli2.png"); turl = getClass().getResource("images/tank.png"); purl = getClass().getResource("images/plane.png"); murl = getClass().getResource("images/missile.png"); eurl = getClass().getResource("images/explosion.png"); try { image = Toolkit.getDefaultToolkit().getImage(bgurl); imageTwo = Toolkit.getDefaultToolkit().getImage(bgurl); chopper = Toolkit.getDefaultToolkit().getImage(curl); chopper2 = Toolkit.getDefaultToolkit().getImage(c2url); tank = Toolkit.getDefaultToolkit().getImage(turl); plane = Toolkit.getDefaultToolkit().getImage(purl); missile = Toolkit.getDefaultToolkit().getImage(murl); explosion = Toolkit.getDefaultToolkit().getImage(eurl); } catch (Exception ex) { System.out.println("File Not Found"); } } // //////// SETS VARIABLES WHEN GAME IS STARTED OR RESTARTED // ////////////////// public void startGame() { bgx = 0; bgxTwo = 800; y = 50; score = 0; holding = false; gameOver = false; time = (int) (Math.random() * 500 + 500); obsNum2 = 0; shooting = false; count = 1; planeSpeed = -6; missileSpeed = -7; planeArray.clear(); tankArray.clear(); missileArray.clear(); colorone = Color.WHITE; colortwo = Color.WHITE; restartColor = Color.white; menuColor = Color.white; movementtimer = new java.util.Timer(); task = new TimerTask() { public void run() { moveImage();repaint(); } }; movementtimer.schedule(task, 0, 13); obstacletimer = new java.util.Timer(); taskTwo = new TimerTask() { public void run() { generateObstacle(); } }; obstacletimer.schedule(taskTwo, 2000, time); } // ////////// COLLISION DETECTION ////////////////// public void moveImage() { moveBackground(); addToScore(); if (holding) { y += -3; } else { y += 3; } for (int i = 0; i < planeArray.size(); i++) { Plane plane = planeArray.get(i); if (y + 30 >= plane.yPos && y + 30 <= plane.yPos + 30 && plane.xPos >= 200 && plane.xPos <= 250 || y >= plane.yPos && y <= plane.yPos + 30 && plane.xPos >= 200 && plane.xPos + 50 <= 250) { gameOver = true; System.out.println("Crash with plane!"); } } for (int i = 0; i < tankArray.size(); i++) { Tank tank = tankArray.get(i); if (y + 30 >= tank.yPos && y + 30 <= tank.yPos + 30 && tank.xPos >= 200 && tank.xPos <= 250 || y >= tank.yPos && y <= tank.yPos + 30 && tank.xPos >= 200 && tank.xPos + 50 <= 250) { gameOver = true; System.out.println("Crash with a tank"); } if (shooting) { if (y + 30 >= tank.bulletYPos && y <= tank.bulletYPos && tank.bulletXPos >= 200 && tank.bulletXPos <= 250) { gameOver = true; System.out.println("Shot down"); } } } for (int i = 0; i < missileArray.size(); i++) { Missile missile = missileArray.get(i); if (y + 30 >= missile.yPos && y + 30 <= missile.yPos + 30 && missile.xPos >= 200 && missile.xPos <= 250 || y >= missile.yPos && y <= missile.yPos + 30 && missile.xPos >= 200 && missile.xPos + 50 <= 250) { gameOver = true; System.out.println("Crash with a missile"); } } if (y >= 300) { gameOver = true; } else if (y <= -15) { gameOver = true; } } // //////// MOVES BACKGROUND ////////////// public void moveBackground() { bgx += -5; if (bgx == -800) { bgx = 800; } bgxTwo += -5; if (bgxTwo == -800) { bgxTwo = 800; } for (int i = 0; i < planeArray.size(); i++) { Plane obs = planeArray.get(i); obs.xPos = obs.xPos - 6; } for (int i = 0; i < tankArray.size(); i++) { Tank obs = tankArray.get(i); obs.xPos = obs.xPos - 5; if (shooting) { obs.bulletYPos = obs.bulletYPos - 2; obs.bulletXPos = obs.bulletXPos - obs.angle; } } for (int i = 0; i < missileArray.size(); i++) { Missile obs = missileArray.get(i); obs.xPos = obs.xPos - 7; } } public void addToScore() { score += 5; increaseDiff(); } public void increaseDiff() { if (score == 10000) { shooting = true; for (int i = 0; i < tankArray.size(); i++) { Tank tank = tankArray.get(i); tank.bulletXPos = tank.xPos; } } if (score > 5000 && score < 9999) { time = (int) (Math.random() * 400 + 250); planeSpeed = -7; missileSpeed = -8; } else if (score > 10000 && score < 14999) { time = (int) (Math.random() * 400 + 150); planeSpeed = -8; missileSpeed = -10; } else if (score > 15000 && score < 19999) { time = (int) (Math.random() * 400 + 150); planeSpeed = -9; missileSpeed = -11; obsNum2 = (int) (Math.random() * 2 + 1); } else if (score > 20000 && score < 29999) { time = (int) (Math.random() * 300 + 100); planeSpeed = -10; missileSpeed = -13; obsNum2 = (int) (Math.random() * 2 + 1); } else if (score > 30000) { time = (int) (Math.random() * 300 + 100); planeSpeed = -12; missileSpeed = -15; obsNum2 = (int) (Math.random() * 2 + 1); } } public void generateObstacle() { obsNum = (int) (Math.random() * 5 + 1); if (obsNum == 1 || obsNum == 4 || obsNum2 == 1) { planeArray.add(new Plane()); } if (obsNum == 2) { tankArray.add(new Tank()); } if (obsNum == 3 || obsNum == 5 || obsNum2 == 2) { missileArray.add(new Missile()); } } public void update(Graphics g) { paint(g); } // /////////////// MAIN PAINT METHOD ////////////////////// @Override public void paint(Graphics g) { g.clearRect(0,0,800,400); if (!startscreen) { g.drawImage(image, bgx, 0, null); g.drawImage(imageTwo, bgxTwo, 0, null); for (int i = 0; i < planeArray.size(); i++) { Plane obs = planeArray.get(i); if (obs.xPos <= -50) { planeArray.remove(i); } else { g.drawImage(plane, obs.xPos, obs.yPos, null); } } for (int i = 0; i < tankArray.size(); i++) { Tank obs = tankArray.get(i); if (obs.xPos <= -50) { tankArray.remove(i); } else { g.drawImage(tank, obs.xPos, obs.yPos, null); if (shooting) { g.setColor(bulletColor); g.fillOval(obs.bulletXPos, obs.bulletYPos, 5, 5); } } } for (int i = 0; i < missileArray.size(); i++) { Missile obs = missileArray.get(i); if (obs.xPos <= -50) { missileArray.remove(i); } else { g.drawImage(missile, obs.xPos, obs.yPos, null); } } if (gameOver) { movementtimer.cancel(); obstacletimer.cancel(); g.setColor(Color.WHITE); g.setFont(f2); g.drawString("GAME OVER", 250, 150); g.setFont(f3); g.drawString("Your score: " + score, 250, 200); g.setColor(restartColor); g.drawString("Click to restart!", 250, 250); g.setColor(menuColor); g.drawString("Back to menu", 250, 300); g.drawImage(explosion, 200, y, this); } } else if (startscreen) { g.drawImage(image, 0, 0, this); g.drawImage(imageTwo, 0, 0, this); g.drawImage(chopper, 200, 50, this); g.setColor(Color.WHITE); g.setFont(f2); g.drawString("Choose a level:", 200, 150); g.setFont(f3); g.setColor(colorone); g.drawString("Grass Level!", 250, 200); g.setColor(colortwo); g.drawString("Snow Level!", 250, 250); } if (count <= 9 && !gameOver && !startscreen) { g.drawImage(chopper, 200, y, this); count++; } else if (count >= 10 && count < 20 && !gameOver && !startscreen) { g.drawImage(chopper2, 200, y, this); count++; } else if (count == 20 && !gameOver && !startscreen) { count = 1; g.drawImage(chopper, 200, y, this); } g.setFont(f1); g.setColor(Color.WHITE); g.drawString(version, 10, 10); g.drawString("Score: " + score + "", 700, 10); } // ///////////////////OVERRIDE KEYPRESSED EVENTS////////////////////// @Override public void keyPressed(KeyEvent e) { // TODO Auto-generated method stub if (e.getKeyCode() == 32) { holding = true; repaint(); } } @Override public void keyReleased(KeyEvent e) { // TODO Auto-generated method stub if (e.getKeyCode() == 32) { holding = false; repaint(); } } @Override public void keyTyped(KeyEvent e) { // TODO Auto-generated method stub } public void mousePressed(MouseEvent e) { if (e.getX() >= 250 && e.getX() <= 400 && e.getY() >= 180 && e.getY() <= 200 && startscreen) { startscreen = false; level = 1; getImages(); startGame(); } if (e.getX() >= 250 && e.getX() <= 400 && e.getY() >= 230 && e.getY() <= 250 && startscreen) { startscreen = false; level = 2; getImages(); startGame(); } if (e.getX() >= 250 && e.getX() <= 420 && e.getY() >= 230 && e.getY() <= 250 && gameOver) { startGame(); } if (e.getX() >= 250 && e.getX() <= 420 && e.getY() >= 280 && e.getY() <= 320 && gameOver) { gameOver = false; startscreen = true; repaint(); } } @Override public void mouseClicked(MouseEvent arg0) { // TODO Auto-generated method stub } @Override public void mouseEntered(MouseEvent e) { // TODO Auto-generated method stub } public void mouseMoved(MouseEvent e) { if (e.getX() >= 250 && e.getX() <= 400 && e.getY() >= 180 && e.getY() <= 200 && startscreen) { colorone = Color.RED; repaint(); } else if (e.getX() >= 250 && e.getX() <= 400 && e.getY() >= 230 && e.getY() <= 250 && startscreen) { colortwo = Color.RED; repaint(); } else if (startscreen) { colorone = Color.white; colortwo = Color.white; repaint(); } if (e.getX() >= 250 && e.getX() <= 420 && e.getY() >= 230 && e.getY() <= 250 && gameOver) { restartColor = Color.red; repaint(); } else if (e.getX() >= 250 && e.getX() <= 420 && e.getY() >= 280 && e.getY() <= 320 && gameOver) { menuColor = Color.red; repaint(); } else if (gameOver) { restartColor = Color.white; menuColor = Color.white; repaint(); } } @Override public void mouseExited(MouseEvent arg0) { // TODO Auto-generated method stub } @Override public void mouseReleased(MouseEvent arg0) { // TODO Auto-generated method stub } @Override public void mouseDragged(MouseEvent arg0) { // TODO Auto-generated method stub } } </code></pre> <p>Sorry about all the code, as you may be able to tell, I am new to Java and programming in general (started last year at college), but it is something I wish to progress with and make a career out of.</p> <p>Thanks Tom</p>

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