I am trying to get a circle to move through the input of a keyboard. I am not able to move the object at all. Can someone help me figure out what is wrong? Here is my code:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JPanel;
public class AlienInvader extends JPanel implements KeyListener{
Constants constant = new Constants();
public void update() {
constant.x += constant.xvel;
addKeyListener(this);
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.MAGENTA);
g.fillOval(constant.x, constant.y, 30, 30);
repaint();
}
#Override
public void keyPressed(KeyEvent e) {
System.out.println(constant.x);
switch(e.getKeyCode()) {
case KeyEvent.VK_LEFT:
constant.xvel = -1;
break;
case KeyEvent.VK_RIGHT:
constant.xvel = 1;
break;
}
}
#Override
public void keyReleased(KeyEvent e) {
switch(e.getKeyCode()) {
case KeyEvent.VK_LEFT:
constant.xvel = -1;
break;
case KeyEvent.VK_RIGHT:
constant.xvel = 1;
break;
}
}
#Override
public void keyTyped(KeyEvent arg0) {
// TODO Auto-generated method stub
}
}
I am not sure what I am doing wrong. I thought it was because I wasn't calling the update method, but when I added a if statement in paintComponent (so it only calls itself once) and tried it, I had no luck.
To start with, don't call repaint within any paintXxx method. Paint methods are typically called in response to a call to repaint, therefore you are creating a nasty, never ending, ever consuming loop of resource hell.
Secondly, KeyListeners only respond to key events when 1- The component the are registered to are focusable 2- When the component they are registered to have focus.
They are a poor choice in this case. Use Key bindings instead
Thirdly, you are not providing a preferredSize hint for layout managers to use. This may or may not be a bad thing in your case, but it's possible that you component will be laid out with a size of 0x0
Example
Something like....
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class MoveCircle {
public static void main(String[] args) {
new MoveCircle();
}
public MoveCircle() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private int xDelta = 0;
private int keyPressCount = 0;
private Timer repaintTimer;
private int xPos = 0;
private int radius = 10;
public TestPane() {
InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap am = getActionMap();
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0, false), "pressed.left");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0, false), "pressed.right");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0, true), "released.left");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0, true), "released.right");
am.put("pressed.left", new MoveAction(-2, true));
am.put("pressed.right", new MoveAction(2, true));
am.put("released.left", new MoveAction(0, false));
am.put("released.right", new MoveAction(0, false));
repaintTimer = new Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
xPos += xDelta;
if (xPos < 0) {
xPos = 0;
} else if (xPos + radius > getWidth()) {
xPos = getWidth() - radius;
}
repaint();
}
});
repaintTimer.setInitialDelay(0);
repaintTimer.setRepeats(true);
repaintTimer.setCoalesce(true);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(Color.RED);
g2d.drawOval(xPos, 0, radius, radius);
g2d.dispose();
}
public class MoveAction extends AbstractAction {
private int direction;
private boolean keyDown;
public MoveAction(int direction, boolean down) {
this.direction = direction;
keyDown = down;
}
#Override
public void actionPerformed(ActionEvent e) {
xDelta = direction;
if (keyDown) {
if (!repaintTimer.isRunning()) {
repaintTimer.start();
}
} else {
repaintTimer.stop();
}
}
}
}
}
For example...
Related
I'm making a 2d game engine and trying to improve the input system. When I try to use the WASD keys, the KeyListener sometimes won't detect the key being pressed but it still detects it being released. I tried using KeyBindings instead but I get the same problem. Anyone know what's going on?
(maybe it has something to do with my IDE(netbeans), mac, or java?)
edit: here's someone else's code that has the same problem
import java.awt.BorderLayout;
import java.awt.Canvas;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private Surface surface;
public TestPane() {
setLayout(new BorderLayout());
surface = new Surface();
InputMap inputMap = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap actionMap = getActionMap();
System.out.println("yo");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_A, 0, false), "Pressed.left");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_A, 0, true), "Release.left");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_D, 0, false), "Pressed.right");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_D, 0, true), "Release.right");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_W, 0, false), "Pressed.up");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_W, 0, true), "Release.up");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_S, 0, false), "Pressed.down");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_S, 0, true), "Release.down");
actionMap.put("Pressed.left", surface.getLeftPressAction());
actionMap.put("Release.left", surface.getLeftReleaseAction());
actionMap.put("Pressed.right", surface.getRightPressAction());
actionMap.put("Release.right", surface.getRightReleaseAction());
actionMap.put("Pressed.up", surface.getUpPressAction());
actionMap.put("Release.up", surface.getUpReleaseAction());
actionMap.put("Pressed.down", surface.getDownPressAction());
actionMap.put("Release.down", surface.getDownReleaseAction());
add(surface);
}
}
public class Surface extends Canvas {
private String displayText = "...";
#Override
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2d = (Graphics2D) g.create();
FontMetrics fm = g2d.getFontMetrics();
int x = (getWidth() - fm.stringWidth(displayText)) / 2;
int y = ((getHeight() - fm.getHeight()) / 2) + fm.getAscent();
g2d.drawString(displayText, x, y);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
public Action getLeftPressAction() {
return new TextAction("Left");
}
public Action getLeftReleaseAction() {
return new ClearAction();
}
public Action getRightPressAction() {
return new TextAction("Right");
}
public Action getRightReleaseAction() {
return new ClearAction();
}
public Action getUpPressAction() {
return new TextAction("Up");
}
public Action getUpReleaseAction() {
return new ClearAction();
}
public Action getDownPressAction() {
return new TextAction("Down");
}
public Action getDownReleaseAction() {
return new ClearAction();
}
public class TextAction extends AbstractAction {
private String text;
public TextAction(String text) {
this.text = text;
}
#Override
public void actionPerformed(ActionEvent e) {
displayText = text;
repaint();
}
}
public class ClearAction extends AbstractAction {
#Override
public void actionPerformed(ActionEvent e) {
displayText = "...";
repaint();
}
}
}
}
I just tried using the jar file in a windows 10 and it worked perfectly... It may have something to do with my operating system or my version of java.
I'm trying to create a program where an object continuously falls down the screen unless the user is pressing space, in which case it moves up. So far I've gotten the object to initially start falling when I run the program. When I press space, the object moves up (like it should). But, when I release the key the object stops moving. I want it to continue falling when the key is released.
I've looked at using key bindings instead of keylistener but I've had trouble with it. I am a highschool student looking to major in computer science so forgive me for not knowing too many advanced coding terms/methods. However, I am one of the best in my class and a fast learner who is eager to solve this problem. Here is my code:
public class htestnew extends JPanel implements ActionListener, KeyListener {
Timer t = new Timer(5, this);
int x = 20, y = 20, vely = 1;
public htestnew() {
t.start();
addKeyListener(this);
setFocusable(true);
setFocusTraversalKeysEnabled(false);
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
ImageIcon background = new ImageIcon("OBJECTEXAMPLE1");
background.paintIcon(this, g, 0, 0);
}
public void actionPerformed(ActionEvent e) {
if (y < 0)
{
vely = 0;
y = 0;
}
if (y > 305) //-70
{
vely = 0;
y = 305;
}
y += vely;
repaint();
}
public void keyPressed(KeyEvent e) {
int code = e.getKeyCode();
if (code == KeyEvent.VK_SPACE) {
vely = -1;
}
}
public void keyTyped(KeyEvent e) {
}
public void keyReleased(KeyEvent e) {
vely = 0;
//I have tried setting this value to 1 but it does not work
}
If it is easier to use keybindings a personal and easy to follow example would be amazing. Thank you.
So, changing...
public void keyReleased(KeyEvent e) {
vely=0;
//I have tried setting this value to 1 but it does not work
}
to...
public void keyReleased(KeyEvent e) {
vely=1;
//I have tried setting this value to 1 but it does not work
}
Basically made it work (after I added in something that actually paints)
import java.awt.Dimension;
import java.awt.EventQueue;
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 javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test extends JPanel implements ActionListener, KeyListener {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new Test());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
Timer t = new Timer(5, this);
int x = 20, y = 20, vely = 1;
public Test() {
t.start();
addKeyListener(this);
setFocusable(true);
setFocusTraversalKeysEnabled(false);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 300);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawRect(x, y, 5, 5);
}
public void actionPerformed(ActionEvent e) {
if (y < 0) {
vely = 0;
y = 0;
}
if (y > 305) //-70
{
vely = 0;
y = 305;
}
y += vely;
repaint();
}
public void keyPressed(KeyEvent e) {
int code = e.getKeyCode();
if (code == KeyEvent.VK_SPACE) {
vely = -1;
}
}
public void keyTyped(KeyEvent e) {
}
public void keyReleased(KeyEvent e) {
vely = 1;
//I have tried setting this value to 1 but it does not work
}
}
I would strongly recommend that you take a look at How to Use Key Bindings instead of using KeyListener, it will solve the core problem with KeyListener
Key Binding Example...
import java.awt.Dimension;
import java.awt.EventQueue;
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 javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test extends JPanel implements ActionListener {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new Test());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
Timer t = new Timer(5, this);
int x = 20, y = 20, vely = 1;
public Test() {
t.start();
addKeyBinding("space.pressed", KeyEvent.VK_SPACE, true, new ChangeYAction(-1));
addKeyBinding("space.released", KeyEvent.VK_SPACE, false, new ChangeYAction(1));
}
protected void addKeyBinding(String name, int virtualKey, boolean pressed, Action action) {
addKeyBinding(name, KeyStroke.getKeyStroke(virtualKey, 0, !pressed), action);
}
protected void addKeyBinding(String name, KeyStroke keyStroke, Action action) {
InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap am = getActionMap();
im.put(keyStroke, name);
am.put(name, action);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 300);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawRect(x, y, 5, 5);
}
public void actionPerformed(ActionEvent e) {
if (y < 0) {
vely = 0;
y = 0;
}
if (y > 305) //-70
{
vely = 0;
y = 305;
}
y += vely;
repaint();
}
public class ChangeYAction extends AbstractAction {
private int changeYTo;
public ChangeYAction(int changeYTo) {
this.changeYTo = changeYTo;
}
#Override
public void actionPerformed(ActionEvent e) {
vely = changeYTo;
}
}
}
When I run the code, the added Example1 class to the JOptionPane (in Frame) should get keyInput and then change the y value of the player instance (in example1), but it doesn't work. Also, how would I be able to rotate the ship on its axis and then move in the direction its facing? Currently it moves in the direction its rotated towards, but it rotates on what seems the coordinates 0,0.
Frame
import javax.swing.*;
import java.awt.*;
/**
* Created by griffin on 12/7/2015.
*/
public class Frame extends JFrame {
public Frame() {
initUI();
}
private void initUI() {
JTabbedPane jtp = new JTabbedPane();
Example1 e1 = new Example1();
Example2 e2 = new Example2();
getContentPane().add(jtp);
jtp.add(e1);
jtp.add(e2);
jtp.addTab("Example 1", e1);
jtp.addTab("Example 2", e2);
setResizable(false);
pack();
setTitle("NLTP");
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new Frame();
frame.setVisible(true);
}
});
}
}
Example1
import javax.swing.*;
import java.awt.*;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.geom.AffineTransform;
/**
* Created by griffin on 12/7/2015.
*/
public class Example1 extends JPanel implements Runnable {
private final int B_WIDTH = 640;
private final int B_HEIGHT = 480;
private int DELAY = 25;
private Thread thread;
Ship player = new Ship(320, 240);
public Example1() {
initScreen();
}
private void initScreen() {
JButton explanation = new JButton("Explanation");
explanation.setBounds(0, 0, 150, 30);
this.setLayout(null);
add(explanation);
addKeyListener(new keyInput());
setFocusable(true);
setBackground(Color.BLACK);
setPreferredSize(new Dimension(B_WIDTH, B_HEIGHT));
setDoubleBuffered(true);
}
#Override
public void addNotify() {
super.addNotify();
thread = new Thread(this);
thread.start();
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
draw(g);
}
public void draw(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
AffineTransform old = g2d.getTransform();
g2d.rotate(Math.toRadians(player.angle));
g2d.drawImage(player.ship, player.x, player.y, null);
g2d.setTransform(old);
Toolkit.getDefaultToolkit().sync();
}
public void cycle() {
player.y += player.vY;
}
#Override
public void run() {
long beforeTime, timeDiff, sleep;
beforeTime = System.currentTimeMillis();
while (true) {
cycle();
repaint();
timeDiff = System.currentTimeMillis() - beforeTime;
sleep = DELAY - timeDiff;
if (sleep < 0) {
sleep = 2;
}
try {
Thread.sleep(sleep);
} catch (InterruptedException e) {
System.out.println("Interrupted: " + e.getMessage());
}
beforeTime = System.currentTimeMillis();
}
}
public class keyInput extends KeyAdapter {
#Override
public void keyReleased(KeyEvent e) {
int key = e.getKeyCode();
if(key == KeyEvent.VK_W) {
}
}
#Override
public void keyTyped(KeyEvent e) {
}
#Override
public void keyPressed(KeyEvent e) {
int key = e.getKeyCode();
if (key == KeyEvent.VK_W) {
player.vY -= 1;
}
if(key == KeyEvent.VK_A) {
player.angle++;
}
if(key == KeyEvent.VK_D) {
player.angle--;
}
}
}
}
KeyListener is well known for having focus related issues. Not only does the component need to be focusable, but it has to have keyboard focus before it will register key events. This is an issue as it's all to easy for your component to lose focus for any number of reasons.
The solution is to use the key bindings API which was designed to help solve this issue. See How to Use Key Bindings for more details.
Swing uses a passive rendering approach. That is, updates occur when ever the API decides something needs to be updated. See Painting in AWT and Swing for more details
What you really need is some kind of active rendering approach, where updates are made on a regular bases. This can be accomplished in a verity of ways, the simplest would be to use a Swing Timer, as it's safe to update the UI (or values that the UI relies on) without the risk of introducing race conditions. See How to use Swing Timers for more details
So, this example basically abstracts the input into four basic movements, rotate left/right and up/down. The code doesn't care how those inputs are generated, only that they can be.
It then uses the key bindings API to register actions for the inputs. This is all done with a single Action class, which just adds the Input to a Set, which the Timer uses to determine what actions should be applied before requesting the UI be repainted.
The rotation is accomplished through the use of a AffineTransform. First we translate the origin to the sprites current x/y position, then rotate it around the center of the sprite. This reduces a lot of the complexity/issues related to rotating things (me simple)
AffineTransform at = AffineTransform.getTranslateInstance(xPos, yPos);
at.rotate(Math.toRadians(angle), sprite.getWidth() / 2, sprite.getHeight() / 2);
g2d.setTransform(at);
g2d.drawImage(sprite, 0, 0, this);
Just beware, a Graphics context is a shared resource, before making these type of changes, you need to make a copy of it (and dispose of it when you are finished)
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.HashSet;
import java.util.Set;
import javax.imageio.ImageIO;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class FlyingPoniesWithGuns {
public static void main(String[] args) {
new FlyingPoniesWithGuns();
}
public FlyingPoniesWithGuns() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
} catch (IOException ex) {
ex.printStackTrace();
}
}
});
}
public enum Input {
ROTATE_LEFT,
ROTATE_RIGHT,
UP,
DOWN
}
public class TestPane extends JPanel {
private BufferedImage sprite;
private double angle;
private int xPos, yPos;
private double xDelta, yDelta;
private Set<Input> inputs;
public TestPane() throws IOException {
inputs = new HashSet<>(25);
sprite = ImageIO.read(getClass().getResource("/Pony.png"));
xPos = (400 - sprite.getWidth()) / 2;
yPos = (400 - sprite.getHeight()) / 2;
addKeyBinding("rotate-left", KeyEvent.VK_A, Input.ROTATE_LEFT);
addKeyBinding("rotate-right", KeyEvent.VK_D, Input.ROTATE_RIGHT);
Timer timer = new Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if (inputs.contains(Input.ROTATE_LEFT)) {
angle -= 5;
} else if (inputs.contains(Input.ROTATE_RIGHT)) {
angle += 5;
}
repaint();
}
});
timer.start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
g2d.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);
g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE);
AffineTransform at = AffineTransform.getTranslateInstance(xPos, yPos);
at.rotate(Math.toRadians(angle), sprite.getWidth() / 2, sprite.getHeight() / 2);
g2d.setTransform(at);
g2d.drawImage(sprite, 0, 0, this);
g2d.dispose();
}
protected void addKeyBinding(String name, int keyCode, Input input) {
InputMap inputMap = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap actionMap = getActionMap();
inputMap.put(KeyStroke.getKeyStroke(keyCode, 0, false), name + ".pressed");
actionMap.put(name + ".pressed", new InputAction(input, true));
inputMap.put(KeyStroke.getKeyStroke(keyCode, 0, true), name + ".released");
actionMap.put(name + ".released", new InputAction(input, false));
}
protected class InputAction extends AbstractAction {
private Input input;
private boolean pressed;
public InputAction(Input input, boolean pressed) {
this.input = input;
this.pressed = pressed;
}
#Override
public void actionPerformed(ActionEvent e) {
if (pressed) {
inputs.add(input);
} else {
inputs.remove(input);
}
}
}
}
}
Okay, what about movement? You could have a look at How do I make an entity move in a direction? and How can I move a sprite in the direction it is facing? for more ideas on how you might be able to achieve that
So I have seen a few threads about this already and I need some help about how to fix it specifically. When you hold down a key, Java will read the first key press, then there will be a small delay, and then it will continuously read the key press until you release the key.
public void keyPressed(KeyEvent key) {
int code = key.getKeyCode();
if (code == KeyEvent.VK_DOWN) {
//Do stuff
}
if (code == KeyEvent.VK_LEFT) {
//Do stuff
}
if (code == KeyEvent.VK_RIGHT) {
//Do stuff
}
if (code == KeyEvent.VK_UP) {
//Do stuff
}
}
That is my current code. I heard that to fix this you can create a timer which rapidly checks for key presses, but I'm not really sure how to do that. Would appreciate some help here or if there is a better solution.
The basic answer to your question is, you can't, the delay is OS specific.
The longer answer is, you should be ignoring the individual events themselves and monitor a change in state (between press and release) through the use of appropriate flags.
This means, that when a key is pressed, you set some flag which you program can use to change the state of the program and when released, you reset it.
This disassociates the event from state change and provides you with much more flexibility, as your program doesn't care what caused the state change, only that the state has changed and it should react to it.
This will require you to have some kind of "loop" whose responsibility it is, is to monitor this change and react to it accordingly. In gaming, this is commonly known as a "game-loop", but can also been known as "main-loop".
It's this "loops" responsibility to update the state of the program and get it painted.
Below is a very simple example which uses the key bindings API and a javax.swing.Timer to demonstrate the basic concepts
import com.sun.glass.events.KeyEvent;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class MoveMe {
public static void main(String[] args) {
new MoveMe();
}
public MoveMe() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class MovementState {
public int xDirection;
public int yDirection;
}
public class TestPane extends JPanel {
private MovementState movementState;
private Rectangle box;
public TestPane() {
movementState = new MovementState();
InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap am = getActionMap();
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0, false), "down-pressed");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0, true), "down-released");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0, false), "up-pressed");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0, true), "up-released");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0, false), "left-pressed");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0, true), "left-released");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0, false), "right-pressed");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0, true), "right-released");
am.put("down-pressed", new YDirectionAction(movementState, 2));
am.put("down-released", new YDirectionAction(movementState, 0));
am.put("up-pressed", new YDirectionAction(movementState, -2));
am.put("up-released", new YDirectionAction(movementState, 0));
am.put("left-pressed", new XDirectionAction(movementState, -2));
am.put("left-released", new XDirectionAction(movementState, 0));
am.put("right-pressed", new XDirectionAction(movementState, 2));
am.put("right-released", new XDirectionAction(movementState, 0));
box = new Rectangle(90, 90, 20, 20);
Timer timer = new Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
box.x += movementState.xDirection;
box.y += movementState.yDirection;
if (box.x < 0) {
box.x = 0;
} else if (box.x + box.width > getWidth()) {
box.x = getWidth() - box.width;
}
if (box.y < 0) {
box.y = 0;
} else if (box.y + box.height > getHeight()) {
box.y = getHeight() - box.height;
}
repaint();
}
});
timer.start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(Color.RED);
g2d.fill(box);
g2d.dispose();
}
}
public abstract class AbstractDirectionAction extends AbstractAction {
private final MovementState movementState;
private final int value;
public AbstractDirectionAction(MovementState movementState, int value) {
this.movementState = movementState;
this.value = value;
}
public MovementState getMovementState() {
return movementState;
}
public int getValue() {
return value;
}
}
public class YDirectionAction extends AbstractDirectionAction {
public YDirectionAction(MovementState movementState, int value) {
super(movementState, value);
}
#Override
public void actionPerformed(ActionEvent e) {
getMovementState().yDirection = getValue();
}
}
public class XDirectionAction extends AbstractDirectionAction {
public XDirectionAction(MovementState movementState, int value) {
super(movementState, value);
}
#Override
public void actionPerformed(ActionEvent e) {
getMovementState().xDirection = getValue();
}
}
}
Im newish to keylistener, but recently I made a little program which will be below, which uses keylistener to make the A,W,S,D keys move a square. Well I used dropbox to get the program on this laptop, and now it doesn't work. It seems weird to me that it works on a keyboard, but not on a laptop keyboard. Any ideas why? Here is the code, well a portion:
public class Game extends JApplet implements KeyListener
{
public boolean isMoving = false;
int test = 0;
Rect r = new Rect();
public void keyPressed(KeyEvent e){}
public void keyReleased(KeyEvent e){} // ignore
public void keyTyped(KeyEvent e)
{
char keyChar = e.getKeyChar();
if (keyChar == KeyEvent.VK_S)
{
r.yVelocity -= 1;
}
if (keyChar == KeyEvent.VK_W)
{
r.yVelocity+=1;
}
if (keyChar == KeyEvent.VK_A)
{
r.xVelocity -=1;
}
if (keyChar == KeyEvent.VK_D)
{
r.xVelocity +=1;
}
}
KeyListener has focus issues. That is, it will only respond to key events when is focusable AND has focus.
The simply solution would be to make the component which the KeyListener is registered to focusable and use requestFocusInWindow, but this makes no gurentees that the component will recieve key board focus.
A better solution would be to use the Key Bindings API which allows you to configure the focus level required for key events to be raised...
Updated with a key bindings example/test
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.geom.AffineTransform;
import java.awt.geom.Path2D;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Set;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class TestKeyBindings {
public static void main(String[] args) {
new TestKeyBindings();
}
public TestKeyBindings() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new KeyPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class KeyPane extends JPanel {
private Triangle up;
private Triangle down;
private Triangle left;
private Triangle right;
private Set<String> activeKeys;
public KeyPane() {
activeKeys = new HashSet<>(4);
up = new Triangle(20);
down = new Triangle(20);
left = new Triangle(20);
right = new Triangle(20);
AffineTransform at = AffineTransform.getRotateInstance(Math.toRadians(-90), 10, 10);
left.transform(at);
at = AffineTransform.getRotateInstance(Math.toRadians(180), 10, 10);
down.transform(at);
at = AffineTransform.getRotateInstance(Math.toRadians(-270), 10, 10);
right.transform(at);
InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0, false), "upPressed");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0, false), "downPressed");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0, false), "leftPressed");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0, false), "rightPressed");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0, true), "upReleased");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0, true), "downReleased");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0, true), "leftReleased");
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0, true), "rightReleased");
ActionMap am = getActionMap();
am.put("upPressed", new DirectionAction("up", true));
am.put("downPressed", new DirectionAction("down", true));
am.put("leftPressed", new DirectionAction("left", true));
am.put("rightPressed", new DirectionAction("right", true));
am.put("upReleased", new DirectionAction("up", false));
am.put("downReleased", new DirectionAction("down", false));
am.put("leftReleased", new DirectionAction("left", false));
am.put("rightReleased", new DirectionAction("right", false));
}
public void addKey(String name) {
activeKeys.add(name);
repaint();
}
public void removeKey(String name) {
activeKeys.remove(name);
repaint();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
int x = (getWidth() - (up.getBounds().width * 3)) / 2;
int y = (getHeight() - 10) / 2;
AffineTransform at = AffineTransform.getTranslateInstance(x, y);
if (activeKeys.contains("left")) {
g2d.fill(left.createTransformedShape(at));
} else {
g2d.draw(left.createTransformedShape(at));
}
at = AffineTransform.getTranslateInstance(x + 40, y);
if (activeKeys.contains("right")) {
g2d.fill(right.createTransformedShape(at));
} else {
g2d.draw(right.createTransformedShape(at));
}
at = AffineTransform.getTranslateInstance(x + 20, y - 20);
if (activeKeys.contains("up")) {
g2d.fill(up.createTransformedShape(at));
} else {
g2d.draw(up.createTransformedShape(at));
}
at = AffineTransform.getTranslateInstance(x + 20, y + 20);
if (activeKeys.contains("down")) {
g2d.fill(down.createTransformedShape(at));
} else {
g2d.draw(down.createTransformedShape(at));
}
g2d.dispose();
}
public class DirectionAction extends AbstractAction {
private String name;
private boolean pressed;
public DirectionAction(String name, boolean pressed) {
this.name = name;
this.pressed = pressed;
}
#Override
public void actionPerformed(ActionEvent e) {
if (pressed) {
addKey(name);
} else {
removeKey(name);
}
}
}
}
public class Triangle extends Path2D.Double {
public Triangle(int size) {
moveTo(size / 2, 0);
lineTo(size, size);
lineTo(0, size);
closePath();
}
}
}