I'm new to java, and have been working on creating a code to get a small picture of a car to move using the keys. My problem is when I add more than 1 buttons to the panel. The function of the button in the code I post is nothing, just prints "button [i] clicked" message. The purpose is for them to read a file and update the locations of the car from the data in the file. This is supposed to be a piece on my Reinforcement Learning project. I thought it would be a good opportunity to learn java since this "graphics package" is not necessary for the project, just a "nice" addition. The code is here:
package graphics;
public class Board extends JPanel implements ActionListener {
private Timer timer;
private Agent agent;
private String button = "button.png";
private Image image;
protected JButton b1;
protected JButton b2;
protected JButton b3;
public Board() {
//Keylistener added for the agent to respond to arrow keys
addKeyListener(new TAdapter());
agent = new Agent();
timer = new Timer(10, this); //10ms timer calls action performed
timer.start();
//This part for the button.
ImageIcon i = new ImageIcon(this.getClass().getResource(button));
image = i.getImage();
b1 = new JButton("1", i);
b1.setVerticalTextPosition(AbstractButton.CENTER);
b1.setHorizontalTextPosition(AbstractButton.LEADING);
b1.setActionCommand("Active1");
b2 = new JButton("2", i);
b2.setVerticalTextPosition(AbstractButton.CENTER);
b2.setHorizontalTextPosition(AbstractButton.LEADING);
b2.setActionCommand("Active2");
b3 = new JButton("3", i);
b3.setVerticalTextPosition(AbstractButton.CENTER);
b3.setHorizontalTextPosition(AbstractButton.LEADING);
b3.setActionCommand("Active3");
b1.addActionListener(this);
b2.addActionListener(this);
b3.addActionListener(this);
add(b1); add(b2); add(b3);
setFocusable(true);
setBackground(Color.BLACK);
setDoubleBuffered(true);
}
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2d = (Graphics2D)g;
//Transformations for the agent to be painted based upon its position and orientation
AffineTransform trans = new AffineTransform();
trans.rotate(Math.toRadians(agent.getTh()), agent.getX()+64, agent.getY()+64);
trans.translate(agent.getX(), agent.getY());
g2d.drawImage(agent.getImage(), trans, this); // Draws agent with said transformations
Toolkit.getDefaultToolkit().sync();
g.dispose();
}
public void actionPerformed(ActionEvent ae) {
b1.setEnabled(true);
b2.setEnabled(true);
b3.setEnabled(true);
if (ae.getActionCommand()=="Active1") {
b1.setEnabled(false);
b2.setEnabled(true);
b3.setEnabled(true);
System.out.println("Clicked 1");
agent.reset();
}
if(ae.getActionCommand()=="Active2") {
b1.setEnabled(true);
b2.setEnabled(false);
b3.setEnabled(true);
System.out.println("Clicked 2");
agent.reset();
}
if (ae.getActionCommand()=="Active3") {
b1.setEnabled(true);
b2.setEnabled(true);
b3.setEnabled(false);
System.out.println("Clicked 3");
agent.reset();
}
agent.move();
repaint();
}
private class TAdapter extends KeyAdapter {
public void keyReleased(KeyEvent e) {
agent.keyReleased(e);
}
public void keyPressed(KeyEvent e) {
agent.keyPressed(e);
}
}
}
Now, the problem is this. If I click button 1, or button 2, the other buttons are disabled and it says "Clicked 1 (or 2)" which is fine. But the agent.move() and repaint() aren't invoked. The car doesn't move when I press the keys. If I then click button 3, the other two buttons are disabled and the car moves with the keys.
If I add buttons in a different order add(b3); add(b2); add(b1); then the same happens but this time its button 1 that works fine.
Problems:
==
to compare Strings, use equals(...)
or equalsIgnoreCase(...)
instead. The problem is that ==
checks for object equality, is String A the same object as String B, and you don't care about this. You want to know if the two Strings hold the same chars in the same order which is where the two methods come in.dispose()
of a Graphics object given you by the JVM as this may mess up the painting of a component's borders, children, and have even other side effects.paint(...)
method but rather in its paintComponent(...)
method just as the tutorials tell you to do. Drawing in paint(...)
can have side effects on a component's borders and children if you're not careful, and also does not have the benefit of default double buffering which is important for smooth animation. paintComponent(...)
fixes all these problems.Thread.sleep(...)
or wait()
/notify()
in it, then yes, you will need to use background threading.For example:
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Stroke;
import java.awt.event.*;
import java.util.EnumMap;
import javax.swing.*;
@SuppressWarnings("serial")
public class KeyBindingPanel extends JPanel {
private static final int PREF_W = 800;
private static final int PREF_H = PREF_W;
private static final Stroke THICK_STROKE = new BasicStroke(5f,
BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND);
private static final int OVAL_WIDTH = 30;
private static final int OVAL_HEIGHT = 30;
private static final Color OVAL_COLOR = Color.red;
private static final Color BKGRD_COLOR = Color.black;
private static final int TIMER_DELAY = 20;
public static final int STEP = 2;
private int myX = 0;
private int myY = 0;
private JButton[] buttons = new JButton[3];
private int condition = WHEN_IN_FOCUSED_WINDOW;
private InputMap inputMap = getInputMap(condition);
private ActionMap actionMap = getActionMap();
private EnumMap<Direction, Boolean> directionMap = new EnumMap<Direction, Boolean>(
Direction.class);
public KeyBindingPanel() {
for (int i = 0; i < buttons.length; i++) {
buttons[i] = new JButton(new ButtonAction());
add(buttons[i]);
}
setBackground(BKGRD_COLOR);
for (final Direction direction : Direction.values()) {
directionMap.put(direction, Boolean.FALSE);
Boolean[] onKeyReleases = { Boolean.TRUE, Boolean.FALSE };
for (Boolean onKeyRelease : onKeyReleases) {
KeyStroke keyStroke = KeyStroke.getKeyStroke(
direction.getKeyCode(), 0, onKeyRelease);
inputMap.put(keyStroke, keyStroke.toString());
actionMap.put(keyStroke.toString(), new DirAction(direction,
onKeyRelease));
}
}
new Timer(TIMER_DELAY, new GameTimerListener()).start();
}
@Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2b = (Graphics2D) g.create();
g2b.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2b.setStroke(THICK_STROKE);
g2b.setColor(OVAL_COLOR);
g2b.drawOval(myX, myY, OVAL_WIDTH, OVAL_HEIGHT);
g2b.dispose(); // since I created this guy
}
private class GameTimerListener implements ActionListener {
@Override
public void actionPerformed(ActionEvent e) {
for (Direction direction : Direction.values()) {
if (directionMap.get(direction)) {
myX += STEP * direction.getRight();
myY += STEP * direction.getDown();
}
}
repaint();
}
}
private class DirAction extends AbstractAction {
private Direction direction;
private boolean onRelease;
public DirAction(Direction direction, boolean onRelease) {
this.direction = direction;
this.onRelease = onRelease;
}
@Override
public void actionPerformed(ActionEvent evt) {
directionMap.put(direction, !onRelease); // it's the opposite!
}
}
private class ButtonAction extends AbstractAction {
public ButtonAction() {
super("Press Me!");
}
@Override
public void actionPerformed(ActionEvent e) {
JButton thisBtn = (JButton) e.getSource();
for (JButton btn : buttons) {
if (btn == thisBtn) {
btn.setEnabled(false);
} else {
btn.setEnabled(true);
}
}
}
}
private static void createAndShowGui() {
JFrame frame = new JFrame("KeyBindingPanel");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new KeyBindingPanel());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
enum Direction {
UP(KeyEvent.VK_UP, -1, 0), DOWN(KeyEvent.VK_DOWN, 1, 0), LEFT(
KeyEvent.VK_LEFT, 0, -1), RIGHT(KeyEvent.VK_RIGHT, 0, 1);
private int keyCode;
private int down;
private int right;
private Direction(int keyCode, int down, int right) {
this.keyCode = keyCode;
this.down = down;
this.right = right;
}
public int getKeyCode() {
return keyCode;
}
public int getDown() {
return down;
}
public int getRight() {
return right;
}
}