Develop Reference

How to make an animated number counter using Java Swing?

I want to make an animated numeric counter, like this one:
I want to be able to input the value and have the counter update with animation.
I can find how to do this on Android from Google, but I cannot find any information on how to make it in Java Swing. How would I make something like this in Swing?

This isn't a complete answer, but this is a working example of a sliding JPanel. This code could be modified to create the display in the question.
Here's the complete runnable example.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.font.FontRenderContext;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class SlidingDigitGUI implements Runnable {
public static void main(String[] args) {
SwingUtilities.invokeLater(new SlidingDigitGUI());
}
private SlidingPanel secondPanel;
#Override
public void run() {
JFrame frame = new JFrame("Sliding Digit");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(createSlidingPanel(), BorderLayout.CENTER);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
Animation animation = new Animation();
new Thread(animation).start();
}
public JPanel createSlidingPanel() {
String[] digitValues = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9" };
JPanel panel = new JPanel();
panel.setBorder(BorderFactory.createLineBorder(Color.LIGHT_GRAY, 4, false));
panel.setPreferredSize(new Dimension(300, 100));
Font font = panel.getFont();
Font derivedFont = font.deriveFont(Font.BOLD, 48F);
secondPanel = new SlidingPanel(digitValues, derivedFont);
secondPanel.setPanelValue("0");
panel.add(secondPanel);
return panel;
}
public class SlidingPanel extends JPanel {
private static final long serialVersionUID = 661553022861652947L;
private static final int MARGIN = 4;
private int imageY;
private BufferedImage slidingImage;
private Dimension characterDimension;
private final Font font;
private String currentValue;
private final String[] panelValues;
public SlidingPanel(String[] panelValues, Font font) {
this.panelValues = panelValues;
this.font = font;
this.characterDimension = calculateFontSize();
this.slidingImage = generateSlidingImage();
this.setPreferredSize(characterDimension);
}
private Dimension calculateFontSize() {
int maxWidth = 0;
int maxHeight = 0;
FontRenderContext frc = new FontRenderContext(null, true, true);
for (String s : panelValues) {
Rectangle2D r2D = font.getStringBounds(s, frc);
int rWidth = (int) Math.round(r2D.getWidth());
int rHeight = (int) Math.round(r2D.getHeight());
maxWidth = Math.max(maxWidth, rWidth);
maxHeight = Math.max(maxHeight, rHeight);
}
return new Dimension(maxWidth, maxHeight);
}
private BufferedImage generateSlidingImage() {
int height = calculateStringHeight() * (panelValues.length + 1);
BufferedImage slidingImage = new BufferedImage(characterDimension.width,
height, BufferedImage.TYPE_INT_RGB);
Graphics g = slidingImage.getGraphics();
g.setColor(Color.WHITE);
g.fillRect(0, 0, characterDimension.width, height);
g.setColor(Color.BLACK);
g.setFont(font);
int y = characterDimension.height - MARGIN;
for (String s : panelValues) {
g.drawString(s, 0, y);
y += calculateStringHeight();
}
g.drawString(panelValues[0], 0, y);
g.dispose();
return slidingImage;
}
public void setPanelValue(String value) {
int index = getValueIndex(value);
this.currentValue = value;
this.imageY = calculateStringHeight() * index;
repaint();
}
public void updatePanelValue(String value) {
if (!currentValue.equals(value)) {
int index = getValueIndex(value);
int finalY = calculateStringHeight() * index;
SliderAnimation sliderAnimation = new SliderAnimation(imageY, finalY);
new Thread(sliderAnimation).start();
this.currentValue = value;
}
}
private int getValueIndex(String value) {
for (int index = 0; index < panelValues.length; index++) {
if (value.equals(panelValues[index])) {
return index;
}
}
return -1;
}
private int calculateStringHeight() {
return characterDimension.height + MARGIN;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
BufferedImage subImage = slidingImage.getSubimage(0, imageY,
characterDimension.width,
characterDimension.height);
g.drawImage(subImage, 0, 0, this);
}
public class SliderAnimation implements Runnable {
private int originalY;
private int finalY;
public SliderAnimation(int originalY, int finalY) {
this.originalY = originalY;
this.finalY = finalY;
}
#Override
public void run() {
int differenceY = finalY - originalY;
if (finalY == 0) {
differenceY = characterDimension.height + MARGIN;
}
int steps = 10;
double difference = (double) differenceY / steps;
for (int index = 1; index <= steps; index++) {
imageY = (int) Math.round(difference * index + originalY);
update();
sleep(120L);
}
if (finalY == 0) {
imageY = 0;
update();
} else {
imageY = finalY;
}
}
private void update() {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
SlidingPanel.this.repaint();
}
});
}
private void sleep(long duration) {
try {
Thread.sleep(duration);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
public class Animation implements Runnable {
#Override
public void run() {
while (true) {
update("3");
sleep(2000L);
update("8");
sleep(2000L);
}
}
private void update(final String value) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
secondPanel.updatePanelValue(value);
}
});
}
private void sleep(long duration) {
try {
Thread.sleep(duration);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}

import java.awt.Dimension;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.Point;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;
public class Animation {
boolean loop=true;//true //loop
static int start=1;//1 //start
static int end=10+1;//20 // end + 1
int delay1=1000;//1s // delay
int delay2=1;//1ms // delay
Font font=new Font("Helvetica",Font.BOLD,25); //Font
Timer timer=new Timer(delay1, e -> move());JPanel panel = new JPanel();int[] size = {50,100};Point point = new Point(210,size[1]);
Timer timer1=null;int value=start-1;int i;
public static void main(String[] args) {if (start!=end) {new Animation();}}
public void move() {
timer.stop();value ++;
if (!loop && value==end) {timer.stop();}i=0;
timer1 = new Timer(delay2, e -> {
if (i==100) {
timer1.stop();
timer.start();
}
point.setLocation(point.getX(), point.getY()-1);
panel.setLocation(point);
panel.revalidate();
i++;
});timer1.start();
if (loop && value==end-1) {point.setLocation(point.getX(),size[1]+size[1]);value = start-1;}else if (value==end-1 && !loop){System.exit(0);}
}
public Animation() {
JFrame frame = new JFrame();frame.setSize(500,300);frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);frame.add(panel);frame.setLocationRelativeTo(null);
panel.setLocation(point);frame.setLayout(null);frame.revalidate();panel.setSize(new Dimension(size[0],size[1]*Math.abs(end-(start-1))));
panel.setLayout(new GridLayout(Math.abs(end-start)+start,1));if (!(end-start<0)) {for (int i=start;i!=(end-start)+start;i++) {JLabel la = new JLabel(String.valueOf(i));la.setFont(font);panel.add(la);
}}timer.start();frame.revalidate();frame.setVisible(true);
}
}

JPanels not being drawn in JFrame

I'm working on a vertical scrolling game, and I'm using a thread to generate new enemies every 2 seconds. Each enemy is an image in a JPanel. For some reason, The generated enemies are not showing up in the JFrame, but they are present. When the player collides with one of the enemies, all the enemies show up.
This is the main class:
package asteroidblaster;
import javax.swing.*;
import javax.swing.Timer;
import java.awt.event.*;
import java.awt.*;
public class Main extends JFrame {
/**
*
*/
private static final long serialVersionUID = 1L;
public Main() {
initUI();
}
private void initUI() {
add(new Board());
setResizable(false);
pack();
setTitle("Alien Blaster");
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args) {
EventQueue.invokeLater(() -> {
JFrame ex = new Main();
ex.setVisible(true);
});
}
}
This is the main game logic:
package asteroidblaster;
import javax.swing.*;
import javax.swing.Timer;
import java.awt.event.*;
import java.awt.*;
import java.util.*;
public class Board extends JPanel {
private static final long serialVersionUID = 1L;
private final int B_WIDTH = 1500;
private final int B_HEIGHT = 700;
private final int REFRESH_TIME = 150;
private AlienShip alien;
private PlayerShip player;
private ArrayList<AlienShip> enemies = new ArrayList<AlienShip>();
private Timer alienScrollTimer, mainTimer;
public Board() {
initBoard();
}
private void initBoard() {
setBackground(Color.BLACK);
setFocusable(true);
setPreferredSize(new Dimension(B_WIDTH, B_HEIGHT));
setPlayer();
initAlienTimer();
gameLoop();
}
private void initAlienTimer() {
alienScrollTimer = new Timer(25, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
for(AlienShip as : enemies) {
as.scrollShip();
}
repaint();
}
});
alienScrollTimer.start();
}
private void setPlayer() {
player = new PlayerShip();
add(player);
addMouseMotionListener(new MouseMotionListener() {
#Override
public void mouseMoved(MouseEvent e) {
player.followMouse(e.getX(), e.getY());
//checkCollision();
repaint();
}
#Override
public void mouseDragged(MouseEvent e) {
}
});
}
private void checkCollision() {
for(AlienShip as : enemies) {
if(player.getBounds().intersects(as.getBounds()))
player.setVisible(false);
}
}
private Thread alienGenerator() {
for(int i = 0; i < 3; i++) { //these two are being drawn
alien = new AlienShip();
add(alien);
enemies.add(alien);
}
return new Thread(new Runnable() {
#Override
public void run() {
int sleepTime = 2000;
while(true) {
try {
Thread.sleep(sleepTime);
} catch(InterruptedException e) {
System.out.println(e);
}
alien = new AlienShip();
add(alien);
enemies.add(alien);
System.out.println("Enemies: " + enemies.size());
}
}
});
}
private void gameLoop() {
alienGenerator().start();
mainTimer = new Timer(REFRESH_TIME, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
checkCollision();
repaint();
}
});
mainTimer.start();
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
}
}
This is the AlienShip class:
package asteroidblaster;
import java.util.Random;
import java.awt.*;
import javax.swing.*;
public class AlienShip extends JPanel {
/**
*
*/
private static final long serialVersionUID = 1L;
private final String ALIEN_SHIP_FILE = "images/alienShip.jpg";
private final int PANEL_WIDTH = 224, PANEL_HEIGHT = 250;
private int panelX, panelY;
private Image alienShipImage;
public AlienShip() {
initAlienShip();
}
private void loadImage() {
alienShipImage = Toolkit.getDefaultToolkit().getImage(ALIEN_SHIP_FILE);
}
public int getX() {
return panelX;
}
public int getY() {
return panelY;
}
private void setY(int yCoord) {
panelY = yCoord;
}
private int setX() {
Random r = new Random();
int rand = r.nextInt(14) + 1;
return panelX = rand * 100;
}
private void initAlienShip() {
panelX = setX();
panelY = 0;
setPreferredSize(new Dimension(PANEL_WIDTH, PANEL_HEIGHT));
setBackground(Color.BLUE);
loadImage();
}
#Override
public Rectangle getBounds() {
return new Rectangle(panelX, panelY, PANEL_WIDTH, PANEL_HEIGHT);
}
public void scrollShip() {
setY(getY() + 1);
}
#Override
public void paint(Graphics g) {
super.paint(g);
g.drawImage(alienShipImage, 0, 0, null);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
}
}

How to implement a physics engine to jump in game [duplicate]

This question already has an answer here:
Implementing gravity in simple 2d game
(1 answer)
Closed 7 years ago.
I need to use a physics engine or something similar to achieve a downward parabolic jump in the game that I have. Right now, the up arrow will just cause the character to float, but I need him to jump.
Here is my code:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.EnumMap;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.swing.*;
#SuppressWarnings("serial")
public class Level extends JPanel {
public static String chicken = "chicken.gif";
public static String chicken2 = "chicken2.gif";
private static final int PREF_W = 1440;
private static final int PREF_H = 500;
private static final int TIMER_DELAY = 20;
private static final String KEY_DOWN = "key down";
private static final String KEY_RELEASE = "key release";
public static final int TRANSLATE_SCALE = 3;
public static final String back = "back.gif";
public static final String corn = "corn.gif";
private EnumMap<Direction, Boolean> dirMap = new EnumMap<Level.Direction, Boolean>(
Direction.class);
private BufferedImage image = null;
private BufferedImage image2 = null;
private BufferedImage image3 = null;
private static int imgX = 20;
private static int imgY = 320;
private static Random rand = new Random();
private static int cImgX = rand.nextInt(1420) + 10;
private static int cImgY = 335;
private static int cornCounter = 0;
private static String Counter = Integer.toString(cornCounter);
private static final Font BG_STRING_FONT = new Font(Font.SANS_SERIF,
Font.BOLD, 32);
private int bgStringX;
public Level() {
for (Direction dir : Direction.values()) {
dirMap.put(dir, Boolean.FALSE);
}
try {
File bback = new File(back);
image2 = ImageIO.read(bback);
File ccorn = new File(corn);
image3 = ImageIO.read(ccorn);
File img = new File(chicken);
image = ImageIO.read(img);
} catch (IOException e) {
e.printStackTrace();
}
new Timer(TIMER_DELAY, new TimerListener()).start();
// here we set up our key bindings
int condition = JComponent.WHEN_IN_FOCUSED_WINDOW;
InputMap inputMap = getInputMap(condition);
ActionMap actionMap = getActionMap();
for (final Direction dir : Direction.values()) {
// for the key down key stroke
KeyStroke keyStroke = KeyStroke.getKeyStroke(dir.getKeyCode(), 0,
false);
inputMap.put(keyStroke, dir.name() + KEY_DOWN);
actionMap.put(dir.name() + KEY_DOWN, new AbstractAction() {
#Override
public void actionPerformed(ActionEvent arg0) {
dirMap.put(dir, true);
}
});
// for the key release key stroke
keyStroke = KeyStroke.getKeyStroke(dir.getKeyCode(), 0, true);
inputMap.put(keyStroke, dir.name() + KEY_RELEASE);
actionMap.put(dir.name() + KEY_RELEASE, new AbstractAction() {
#Override
public void actionPerformed(ActionEvent arg0) {
dirMap.put(dir, false);
}
});
}
FontMetrics fontMetrics = getFontMetrics(BG_STRING_FONT);
int w = fontMetrics.stringWidth(Counter);
bgStringX = (PREF_W - w) / 2;
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
if (image != null) {
g.drawImage(image2, 0, 0, this);
validate();
g.drawImage(image3, cImgX, cImgY, this);
validate();
g.drawImage(image, imgX, imgY, this);
validate();
}
g.setFont(BG_STRING_FONT);
g.setColor(Color.BLACK);
g2.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,
RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
g.drawString(Counter, bgStringX, 190);
}
private class TimerListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
for (Direction dir : Direction.values()) {
if (dirMap.get(dir)) {
imgX += dir.getX() * TRANSLATE_SCALE;
imgY += dir.getY() * TRANSLATE_SCALE;
//System.out.println(imgY);
if(imgX >= 188 && imgX <= 380) {
if(imgY <= 190 && imgY >= 199) {
imgY = 194;
}
}
if (imgX >= (cImgX - 10) && imgX <= (cImgX + 10)) {
cImgX = rand.nextInt(1420) + 10;
repaint();
validate();
cornCounter += 1;
Counter = Integer.toString(cornCounter);
//System.out.println(cornCounter);
repaint();
validate();
}
if(imgX <= -60) {
imgX = 1373;
repaint();
validate();
}
else if(imgX >= 1442) {
imgX = 1;
repaint();
validate();
}
if(imgY >= 320) {
imgY = 320;
}
else if(imgY <= 1) {
imgY = 1;
}
}
}
repaint();
};
}
enum Direction {
Up(KeyEvent.VK_UP, 0, -1),
Left(KeyEvent.VK_A, -1, 0), Right(KeyEvent.VK_D, 1, 0),
LeftA(KeyEvent.VK_LEFT, -1, 0), RightA(KeyEvent.VK_RIGHT, 1, 0),
Down(KeyEvent.VK_DOWN, 0, 1);
private int keyCode;
private int x;
private int y;
private Direction(int keyCode, int x, int y) {
this.keyCode = keyCode;
this.x = x;
this.y = y;
}
public int getKeyCode() {
return keyCode;
}
public int getX() {
return x;
}
public int getY() {
return y;
}
}
private static void createAndShowGui() {
Level mainPanel = new Level();
JFrame frame = new JFrame("Cockadoodle Duty: Awakening");
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() {
#Override
public void run() {
createAndShowGui();
}
});
}
}

That would be an overkill if you just want to achieve a simple jumping motion.
int vy = 0; //velocity of y
//.... heres your update code:
y += vy; //y is the yposition of your image or character
vy += GRAVITY; //GRAVITY is some arbitrary positive value
//...here's your onJump method:
vy = jumpSpeed; //jumpSpeed is some arbitrary negative value

Display X Y coordinates whilst moving Cube in JFrame

I'm learning Java and would really appreciate some help.
I'm trying to get this effect http://tinypic.com/r/339p0ud/8
I using stack overflow 'MOVE CUBE' example:
How Do I Use KeyEventDispatcher
and
stack overflow 'Click coordinate' example:
Using the coordinate plane in the JFrame
I wish to join them together, so that I have a cube I can move around with my keys and
as I do the coordinates show up next to the cube (so the coordinates move with the cube) and change as the position changes.
I would be fascinated to see how this is done as I have tried my best the past week with no success.
thanks in advance for any help or tips you provide here,
Joe
MOVE.java (move the block around with keys)
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import javax.imageio.ImageIO;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.Timer;
public class Move extends JPanel {
public static final long serialVersionUID = 1L;
public static final String IMAGE_PATH = "http://mathforum.org/alejandre/magic.square/4x4grid.gif";
public static final String IMAGE_PATH_PLAYER = "http://upload.wikimedia.org/wikipedia/commons/thumb/c/c1/Square-symbol.svg/50px-Square-symbol.svg.png";
public static final int STEP = 3;
public static final int TIMER_DELAY = STEP * 8;
public BufferedImage bkgrndImage = null;
public BufferedImage playerImage = null;
public Map<Direction, Boolean> directionMap = new HashMap<Direction, Boolean>();
public int playerX = 0;
public int playerY = 0;
enum Direction {
UP(KeyEvent.VK_UP, 0, -1), DOWN(KeyEvent.VK_DOWN, 0, 1),
LEFT(KeyEvent.VK_LEFT, -1, 0), RIGHT(KeyEvent.VK_RIGHT, 1, 0);
public int keyCode;
public int xDirection;
public int yDirection;
private Direction(int keyCode, int xDirection, int yDirection) {
this.keyCode = keyCode;
this.xDirection = xDirection;
this.yDirection = yDirection;
}
public int getKeyCode() {
return keyCode;
}
public int getXDirection() {
return xDirection;
}
public int getYDirection() {
return yDirection;
}
}
public Move() {
try {
URL bkgrdImageURL = new URL(IMAGE_PATH);
URL playerImageURL = new URL(IMAGE_PATH_PLAYER);
bkgrndImage = ImageIO.read(bkgrdImageURL);
playerImage = ImageIO.read(playerImageURL);
setPreferredSize(new Dimension(bkgrndImage.getWidth(), bkgrndImage.getHeight()));
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
for (Direction direction : Direction.values()) {
directionMap.put(direction, false);
}
setKeyBindings();
Timer timer = new Timer(TIMER_DELAY, new TimerListener());
timer.start();
}
public void setKeyBindings() {
InputMap inMap = getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
ActionMap actMap = getActionMap();
for (final Direction direction : Direction.values()) {
KeyStroke pressed = KeyStroke.getKeyStroke(direction.getKeyCode(), 0, false);
KeyStroke released = KeyStroke.getKeyStroke(direction.getKeyCode(), 0, true);
inMap.put(pressed, direction.toString() + "pressed");
inMap.put(released, direction.toString() + "released");
actMap.put(direction.toString() + "pressed", new AbstractAction() {
public static final long serialVersionUID = 1L;
#Override
public void actionPerformed(ActionEvent e) {
directionMap.put(direction, true);
}
});
actMap.put(direction.toString() + "released", new AbstractAction() {
public static final long serialVersionUID = 1L;
#Override
public void actionPerformed(ActionEvent e) {
directionMap.put(direction, false);
}
});
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (bkgrndImage != null) {
g.drawImage(bkgrndImage, 0, 0, null);
}
if (playerImage != null) {
g.drawImage(playerImage, playerX, playerY, null);
}
}
public class TimerListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
boolean moved = false;
for (Direction direction : Direction.values()) {
if (directionMap.get(direction)) {
playerX += STEP * direction.getXDirection();
playerY += STEP * direction.getYDirection();
moved = true;
}
}
if (moved) {
int x = playerX - 2 * STEP;
int y = playerY - 2 * STEP;
int w = playerImage.getWidth() + 4 * STEP;
int h = playerImage.getHeight() + 4 * STEP;
Move.this.repaint(x, y, w, h); // !! repaint just the player
}
}
}
public static void createAndShowUI() {
JFrame frame = new JFrame("MoveIcon");
frame.getContentPane().add(new Move());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
createAndShowUI();
}
});
}
COORDINATE.java (get x and y position in JFrame)
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Coordinate
{
private int x;
private int y;
private String text;
private DrawingBase canvas;
private void displayGUI()
{
JFrame frame = new JFrame("Drawing Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
canvas = new DrawingBase();
canvas.addMouseListener(new MouseAdapter()
{
public void mouseClicked(MouseEvent me)
{
text = "X : " + me.getX() + " Y : " + me.getY();
x = me.getX();
y = me.getY();
canvas.setValues(text, x, y);
}
});
frame.setContentPane(canvas);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
new Coordinate().displayGUI();
}
});
}
}
class DrawingBase extends JPanel
{
private String clickedAt = "";
private int x = 0;
private int y = 0;
public void setValues(String text, int x, int y)
{
clickedAt = text;
this.x = x;
this.y = y;
repaint();
}
public Dimension getPreferredSize()
{
return (new Dimension(500, 400));
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
g.drawString(clickedAt, x, y);
}
}

No sure if this is what you want, I removed Coordinate and did everything in one class
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseListener;
import java.awt.image.BufferedImage;
import java.awt.image.TileObserver;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import javax.imageio.ImageIO;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.Timer;
import org.w3c.dom.events.EventTarget;
import org.w3c.dom.events.MouseEvent;
import org.w3c.dom.views.AbstractView;
public class Move extends JPanel{
public static final long serialVersionUID = 1L;
public static final String IMAGE_PATH = "http://mathforum.org/alejandre/magic.square/4x4grid.gif";
public static final String IMAGE_PATH_PLAYER = "http://upload.wikimedia.org/wikipedia/commons/thumb/c/c1/Square-symbol.svg/50px-Square-symbol.svg.png";
public static final int STEP = 3;
public static final int TIMER_DELAY = STEP * 8;
public BufferedImage bkgrndImage = null;
public BufferedImage playerImage = null;
public Map<Direction, Boolean> directionMap = new HashMap<Direction, Boolean>();
public int playerX = 0;
public int playerY = 0;
private static int xPosition = 0;
private static int yPosition = 0;
private String s = "";
private JLabel jlbl1 = new JLabel("");
enum Direction {
UP(KeyEvent.VK_UP, 0, -1), DOWN(KeyEvent.VK_DOWN, 0, 1),
LEFT(KeyEvent.VK_LEFT, -1, 0), RIGHT(KeyEvent.VK_RIGHT, 1, 0);
public int keyCode;
public int xDirection;
public int yDirection;
private Direction(int keyCode, int xDirection, int yDirection) {
this.keyCode = keyCode;
this.xDirection = xDirection;
this.yDirection = yDirection;
}
public int getKeyCode() {
return keyCode;
}
public int getXDirection() {
return xDirection;
}
public int getYDirection() {
return yDirection;
}
}
public Move() {
this.add(jlbl1,new Dimension(100,100));
try {
URL bkgrdImageURL = new URL(IMAGE_PATH);
URL playerImageURL = new URL(IMAGE_PATH_PLAYER);
bkgrndImage = ImageIO.read(bkgrdImageURL);
playerImage = ImageIO.read(playerImageURL);
setPreferredSize(new Dimension(bkgrndImage.getWidth(), bkgrndImage.getHeight()));
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
for (Direction direction : Direction.values()) {
directionMap.put(direction, false);
}
setKeyBindings();
Timer timer = new Timer(TIMER_DELAY, new TimerListener());
timer.start();
}
public void setKeyBindings() {
InputMap inMap = getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
ActionMap actMap = getActionMap();
for (final Direction direction : Direction.values()) {
KeyStroke pressed = KeyStroke.getKeyStroke(direction.getKeyCode(), 0, false);
KeyStroke released = KeyStroke.getKeyStroke(direction.getKeyCode(), 0, true);
inMap.put(pressed, direction.toString() + "pressed");
inMap.put(released, direction.toString() + "released");
actMap.put(direction.toString() + "pressed", new AbstractAction() {
public static final long serialVersionUID = 1L;
#Override
public void actionPerformed(ActionEvent e) {
directionMap.put(direction, true);
}
});
actMap.put(direction.toString() + "released", new AbstractAction() {
public static final long serialVersionUID = 1L;
#Override
public void actionPerformed(ActionEvent e) {
directionMap.put(direction, false);
}
});
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (bkgrndImage != null) {
g.drawImage(bkgrndImage, 0, 0, null);
}
if (playerImage != null) {
g.drawImage(playerImage, playerX, playerY, null);
}
}
public class TimerListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
boolean moved = false;
for (Direction direction : Direction.values()) {
if (directionMap.get(direction)) {
playerX += STEP * direction.getXDirection();
playerY += STEP * direction.getYDirection();
moved = true;
}
}
if (moved) {
int x = playerX - 2 * STEP;
int y = playerY - 2 * STEP;
int w = playerImage.getWidth() + 4 * STEP;
int h = playerImage.getHeight() + 4 * STEP;
Move.this.repaint(x, y, w, h); // !! repaint just the player
}
s = playerX+", "+playerY;
jlbl1.setText(s);
}
}
public static void createAndShowUI() {
JFrame frame = new JFrame("MoveIcon");
frame.getContentPane().add(new Move());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
createAndShowUI();
}
});
}
}

#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (bkgrndImage != null) {
g.drawImage(bkgrndImage, 0, 0, null);
}
if (playerImage != null) {
g.drawImage(playerImage, playerX, playerY, null);
//offsetX and offsetY are the location relative to the cube to draw the string
//also note that the y coordinate is the location where the BOTTOM of the string begins
g.drawString("Clicked at: " + playerX + "," + playerY + ".", playerX + offsetX, playerY + offsetY)
}
}
This will draw to the location of the player. I can't imagine that it requires much effort to adjust it to draw to the clicked position.

Java keyboard input - game development

I have a specific "problem" with a game I'm creating for class.
The game is an implementation of "Break it". To move the platform at the bottom I just used a key listener. The problem is that after the first key press there is a short "lag" or "stutter" before the platform starts moving. How could I prevent this to get a smooth response? Is there another way than KeyListener? KeyBindings?
Here is the key listener implementation
private class KeyControl implements KeyListener {
private int dx = 20;
public void keyPressed(KeyEvent e) {
if(e.getKeyCode() == KeyEvent.VK_RIGHT) {
if(dx < 0 )
dx = -dx;
gamePanel.movePlatform(dx);
}
if(e.getKeyCode() == KeyEvent.VK_LEFT) {
if(dx > 0 )
dx = -dx;
gamePanel.movePlatform(dx);
}
if(e.getKeyCode() == KeyEvent.VK_SPACE) {
System.out.println("space");
gamePanel.play();
}
if(e.getKeyCode() == KeyEvent.VK_ESCAPE) {
gamePanel.pause();
}
}
}
and here is the method that moves the platform around
public void movePlatform(int dx) {
int nextDX = dx;
if(paused || init) {
dx = 0;
}
// make sure platform doesnt exceed right border
if(platform.getX() + platform.getWidth() + dx> size.getWidth()) {
if(nextDX < 0)
dx = nextDX;
else
dx = 0;
}
// make sure platform doesnt exceed left border
if(platform.getX() + dx <= 0) {
if(nextDX > 0)
dx = nextDX;
else
dx = 0;
}
platform.setFrame(platform.getX() + dx, platform.getY(), platform.getWidth(), platform.getHeight());
platformIntervalX = new Interval((int)platform.getX(), (int)(platform.getX() + platform.getWidth()));
platformIntervalY = new Interval((int)(platform.getY() - platform.getHeight()), (int)platform.getY());
repaint();
}

The solution is not to use the KeyListener's key press for moving your sprite. The key is not to rely on the hardware-specific key press frequency, to use a Swing Timer to create your own frequency. Instead use Key Bindings and a Swing Timer. Start the time on key press and stop it on key release.
For example, run this code and press and release the up-arrow key:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import javax.swing.*;
#SuppressWarnings("serial")
public class KeyBindingEg extends JPanel {
private static final String UP_KEY_PRESSED = "up key pressed";
private static final String UP_KEY_RELEASED = "up key released";
private static final int UP_TIMER_DELAY = 50;
private static final Color FLASH_COLOR = Color.red;
private Timer upTimer;
private JLabel label = new JLabel();
public KeyBindingEg() {
label.setFont(label.getFont().deriveFont(Font.BOLD, 32));
label.setOpaque(true);
add(label);
setPreferredSize(new Dimension(400, 300));
int condition = WHEN_IN_FOCUSED_WINDOW;
InputMap inputMap = getInputMap(condition);
ActionMap actionMap = getActionMap();
KeyStroke upKeyPressed = KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0, false);
KeyStroke upKeyReleased = KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0, true);
inputMap.put(upKeyPressed, UP_KEY_PRESSED);
inputMap.put(upKeyReleased, UP_KEY_RELEASED);
actionMap.put(UP_KEY_PRESSED, new UpAction(false));
actionMap.put(UP_KEY_RELEASED, new UpAction(true));
}
private class UpAction extends AbstractAction {
private boolean onKeyRelease;
public UpAction(boolean onKeyRelease) {
this.onKeyRelease = onKeyRelease;
}
#Override
public void actionPerformed(ActionEvent evt) {
if (!onKeyRelease) {
if (upTimer != null && upTimer.isRunning()) {
return;
}
System.out.println("key pressed");
label.setText(UP_KEY_PRESSED);
upTimer = new Timer(UP_TIMER_DELAY, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
Color c = label.getBackground();
if (FLASH_COLOR.equals(c)) {
label.setBackground(null);
label.setForeground(Color.black);
} else {
label.setBackground(FLASH_COLOR);
label.setForeground(Color.white);
}
}
});
upTimer.start();
} else {
System.out.println("Key released");
if (upTimer != null && upTimer.isRunning()) {
upTimer.stop();
upTimer = null;
}
label.setText("");
}
}
}
private static void createAndShowGui() {
KeyBindingEg mainPanel = new KeyBindingEg();
JFrame frame = new JFrame("KeyBindingEg");
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
Or a better example, one that moves a sprite in any direction based on a key press of one of the arrow keys. No delay encountered:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.image.BufferedImage;
import java.util.EnumMap;
import java.util.Map;
import javax.swing.*;
#SuppressWarnings("serial")
public class KeyBindingEg2 extends JPanel {
enum Dir {
LEFT("Left", KeyEvent.VK_LEFT, -1, 0),
RIGHT("Right", KeyEvent.VK_RIGHT, 1, 0),
UP("Up", KeyEvent.VK_UP, 0, -1),
DOWN("Down", KeyEvent.VK_DOWN, 0, 1);
private String name;
private int keyCode;
private int deltaX;
private int deltaY;
private Dir(String name, int keyCode, int deltaX, int deltaY) {
this.name = name;
this.keyCode = keyCode;
this.deltaX = deltaX;
this.deltaY = deltaY;
}
public String getName() {
return name;
}
public int getKeyCode() {
return keyCode;
}
public int getDeltaX() {
return deltaX;
}
public int getDeltaY() {
return deltaY;
}
}
public static final int TIMER_DELAY = 10;
public static final int DELTA_X = 2;
public static final int DELTA_Y = DELTA_X;
public static final int SPRITE_WIDTH = 10;
public static final int SPRITE_HEIGHT = SPRITE_WIDTH;
private static final String PRESSED = "pressed";
private static final String RELEASED = "released";
private static final int PREF_W = 800;
private static final int PREF_H = 650;
private Map<Dir, Boolean> dirMap = new EnumMap<>(Dir.class);
private int spriteX = 0;
private int spriteY = 0;
private BufferedImage sprite;
private Timer animationTimer = new Timer(TIMER_DELAY, new AnimationListener());
public KeyBindingEg2() {
for (Dir dir : Dir.values()) {
dirMap.put(dir, Boolean.FALSE);
}
sprite = createSprite();
setKeyBindings();
animationTimer.start();
}
private BufferedImage createSprite() {
BufferedImage sprt = new BufferedImage(SPRITE_WIDTH, SPRITE_HEIGHT, BufferedImage.TYPE_INT_ARGB);
Graphics g = sprt.getGraphics();
g.setColor(Color.RED);
g.fillRect(0, 0, SPRITE_WIDTH, SPRITE_HEIGHT);
g.dispose();
return sprt;
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (sprite != null) {
g.drawImage(sprite, spriteX, spriteY, this);
}
}
private void setKeyBindings() {
int condition = WHEN_IN_FOCUSED_WINDOW;
InputMap inputMap = getInputMap(condition);
ActionMap actionMap = getActionMap();
for (Dir dir : Dir.values()) {
KeyStroke keyPressed = KeyStroke.getKeyStroke(dir.getKeyCode(), 0, false);
KeyStroke keyReleased = KeyStroke.getKeyStroke(dir.getKeyCode(), 0, true);
inputMap.put(keyPressed, dir.toString() + PRESSED);
inputMap.put(keyReleased, dir.toString() + RELEASED);
actionMap.put(dir.toString() + PRESSED, new DirAction(dir, PRESSED));
actionMap.put(dir.toString() + RELEASED, new DirAction(dir, RELEASED));
}
}
private class AnimationListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
int newX = spriteX;
int newY = spriteY;
for (Dir dir : Dir.values()) {
if (dirMap.get(dir)) {
newX += dir.getDeltaX() * DELTA_X;
newY += dir.getDeltaY() * DELTA_Y;
}
}
if (newX < 0 || newY < 0) {
return;
}
if (newX + SPRITE_WIDTH > getWidth() || newY + SPRITE_HEIGHT > getHeight()) {
return;
}
spriteX = newX;
spriteY = newY;
repaint();
}
}
private class DirAction extends AbstractAction {
private String pressedOrReleased;
private Dir dir;
public DirAction(Dir dir, String pressedOrReleased) {
this.dir = dir;
this.pressedOrReleased = pressedOrReleased;
}
#Override
public void actionPerformed(ActionEvent evt) {
if (pressedOrReleased.equals(PRESSED)) {
dirMap.put(dir, Boolean.TRUE);
} else if (pressedOrReleased.equals(RELEASED)) {
dirMap.put(dir, Boolean.FALSE);
}
}
}
private static void createAndShowGui() {
KeyBindingEg2 mainPanel = new KeyBindingEg2();
JFrame frame = new JFrame("KeyBindingEg");
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();
}
});
}
}