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how to move multiple objects in JPanel

I want to create multiple squares that move independently and at the same time,and I think the most efficient way is through the transform method in Graphics2D,but I'm not sure how to make it work for each square.I want the square object to be self contained and create its own transforms(instance transforms). Here's what I have so far.
TransformPanel
import javax.swing.*;
import java.awt.*;
import java.awt.geom.AffineTransform;
import java.util.Random;
import java.util.concurrent.TimeUnit;
public class TranformPanel extends JPanel {
private int[] xcoords = {250,248,253,255,249};
private int[] ycoords = {250,253,249,245,250};
private double randomx = 0;
private double randomy = 0;
public void paintComponent(Graphics g)
{
super.paintComponent(g);
drawTransform(g,randomx,randomy);
}
private void drawTransform(Graphics g,double randomx,double randomy)
{
Random rn = new Random();
int xnum = rn.nextInt(10)-5;
randomx = xnum;
int ynum = rn.nextInt(10)-5;
randomy = ynum;
Rectangle rect = new Rectangle(250,250,10,10);
AffineTransform transform = new AffineTransform();
Graphics2D g2d = (Graphics2D)g;
transform.translate(randomx,randomy);
g2d.draw(transform.createTransformedShape(rect));
}
}
TransformDraw
import java.awt.*;
import javax.swing.*;
import java.awt.geom.AffineTransform;
import java.util.Scanner;
import java.util.concurrent.TimeUnit;
public class TransformDraw{
private static TranformPanel panel = new TranformPanel();
public static void main(String[] args) {
// Setup our JFrame details
JFrame frame = new JFrame();
frame.setTitle("Transform Polygon Example");
frame.setSize(500,500);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.setVisible(true);
frame.add(panel);
Scanner input = new Scanner(System.in);
for (int i=0;i<10;i++)
{
try {
TimeUnit.SECONDS.sleep(1);
frame.repaint();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
Thanks is Advance!

Start by creating something that can manage it's location (and other properties) and which can be "painted"
public interface Box {
public void update(Dimension size);
public void paint(Graphics2D g2d);
}
So, this is pretty basic, all it can do is be updated (within a given area) and be painted. You could expose other properties (like it's bounding box for example) based on your particular needs
Next, we need a simple implementation, something like...
public class DefaultBox implements Box {
private Color color;
private Rectangle bounds;
private int xDelta;
private int yDelta;
public DefaultBox(Color color, Dimension size) {
this.color = color;
bounds = new Rectangle(new Point(0, 0), size);
xDelta = 1 + (int) (Math.random() * 10);
yDelta = 1 + (int) (Math.random() * 10);
}
#Override
public void update(Dimension size) {
bounds.x += xDelta;
bounds.y += yDelta;
if (bounds.x < 0) {
bounds.x = 0;
xDelta *= -1;
} else if (bounds.x + bounds.width > size.width) {
bounds.x = size.width - bounds.width;
xDelta *= -1;
}
if (bounds.y < 0) {
bounds.y = 0;
yDelta *= -1;
} else if (bounds.y + bounds.height > size.height) {
bounds.y = size.height - bounds.height;
yDelta *= -1;
}
}
#Override
public void paint(Graphics2D g2d) {
g2d.setColor(color);
g2d.fill(bounds);
}
}
Now, this maintains a simple Rectangle instance, which describes the location and size of the object, it also maintains properties about the color and it's speed.
When update is called, it updates it's location and does some simple bounds checking to make sure that the box remains within the specified area.
When paint is called, it simply paints itself.
Finally, we need some way to update and paint these boxes....
public class TestPane extends JPanel {
private List<Box> boxes;
private Color[] colors = {Color.RED, Color.BLACK, Color.BLUE, Color.CYAN, Color.DARK_GRAY, Color.GREEN, Color.LIGHT_GRAY, Color.MAGENTA, Color.ORANGE, Color.PINK, Color.WHITE, Color.YELLOW};
public TestPane() {
boxes = new ArrayList<>(25);
for (int index = 0; index < 100; index++) {
Color color = colors[(int) (Math.random() * colors.length)];
int width = 10 + (int) (Math.random() * 9);
int height = 10 + (int) (Math.random() * 9);
boxes.add(new DefaultBox(color, new Dimension(width, height)));
}
Timer timer = new Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
for (Box box : boxes) {
box.update(getSize());
}
repaint();
}
});
timer.start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
for (Box box : boxes) {
Graphics2D g2d = (Graphics2D) g.create();
box.paint(g2d);
g2d.dispose();
}
}
}
Okay, so again, this is pretty simple. It maintains a List of Box's, a Swing Timer to periodically update the List of Box's, calling their update method. The Timer the simply calls repaint, which (in a round about way) ends up calling paintComponent, which then just calls paint on each instance of Box.
100 boxes...

How do I rotate objects/images independently in Java?

I am trying to have a series of rectangles rotating about their respective centres and moving to the right, but since the plane contains all the rectangles, all the rectangles rotate in unison about the centre of the latest added rectangle instead of independently around their respective centres. Here are the codes:
The main program:
import java.awt.Graphics2D;
import java.util.ArrayList;
public class Rectangles {
public static final int SCREEN_WIDTH = 400;
public static final int SCREEN_HEIGHT = 400;
public static void main(String[] args) throws Exception {
Rectangles game = new Rectangles();
game.play();
}
public void play() {
board.setupAndDisplay();
}
public Rectangles() {
board = new Board(SCREEN_WIDTH, SCREEN_HEIGHT, this);
rectangle_2 = new Rectangle_2();
rectangles = new ArrayList<Rectangle_2>();
}
public void drawRectangles(Graphics2D g, float elapsedTime) {
ticks++;
if (ticks % 4000 == 0) {
Rectangle_2 rectangle = new Rectangle_2();
rectangles.add(rectangle);
}
rotateRectangles(g);
drawRectangles(g);
moveRectangles(elapsedTime);
for (int i = 0; i < rectangles.size(); i++) {
Rectangle_2 rectangle = rectangles.get(i);
if (rectangle.getX() < -75) {
rectangles.remove(i);
i--;
}
}
}
public void drawRectangles(Graphics2D g) {
for (Rectangle_2 rectangle: rectangles) {
rectangle.drawRectangle(g);
}
}
public void rotateRectangles(Graphics2D g) {
for (Rectangle_2 rectangle: rectangles) {
rectangle.rotateRectangle(g);
}
}
public void moveRectangles(float elapsedTime) {
for (Rectangle_2 rectangle: rectangles) {
rectangle.move(10 * elapsedTime);
}
}
private Board board;
private Rectangle_2 rectangle_2;
private int ticks = 0;
private ArrayList<Rectangle_2> rectangles;
}
The rectangle class:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
public class Rectangle_2 {
public Rectangle_2() {
x = 0;
y = 200;
rectangle = new Rectangle((int) x, (int) y, 25, 25);
}
public void drawRectangle(Graphics2D g) {
g.setColor(Color.red);
g.draw(rectangle);
}
public void rotateRectangle(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
angle += 0.001;
g2.rotate(angle, rectangle.getX() + rectangle.getWidth() / 2, rectangle.getY() + rectangle.getHeight() / 2);
g2.setColor(Color.red);
}
public void move(float elapsedTime) {
x = x + elapsedTime;
rectangle.setLocation((int) x, (int) y);
}
public boolean collides(Rectangle r) {
return r.intersects(rectangle);
}
#Override
public String toString() {
return "Pipe [x = " + x + ", y = " + y + ", rectangle = " + rectangle + "]";
}
public Rectangle getRectangle() {
return rectangle;
}
public double getX() {
return x;
}
private double x;
private double y;
private double angle = 0;
private Rectangle rectangle;
}
The board class where the animation takes place:
import java.awt.*;
import javax.swing.*;
public class Board extends JPanel {
private static final long serialVersionUID = 1L;
public Board(int width_, int height_, Rectangles simulator_) {
width = width_;
height = height_;
game = simulator_;
lastTime = -1L;
}
public void setupAndDisplay() {
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(new JScrollPane(this));
f.setSize(width, height);
f.setLocation(200, 200);
f.setVisible(true);
this.setFocusable(true);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
boolean first = (lastTime == -1L);
long elapsedTime = System.nanoTime() - lastTime;
lastTime = System.nanoTime();
g.setColor(Color.white);
g.fillRect(0, 0, width, height);
g.setColor(Color.white);
game.drawRectangles((Graphics2D) g, (first ? 0.0f : (float) elapsedTime / 1e9f));
repaint();
}
private int width;
private int height;
private long lastTime;
private Rectangles game;
}
Please note the rectangle takes a couple of seconds to appear because of the delay implemented. Thank you :).

The Graphics context is a shared resource, that is, during a single paint cycle, all the components get the same Graphics context. Any changes you make to the Graphics context are also maintained (or compound in the case of same transformations). So this means, each time you call Graphics#rotate, you are actually compounding any of the previous rotations which might have been executed on it.
You need to change you code in two ways...
You need a independent update cycle, independent of the paint cycle
Create a local copy of the Graphics context BEFORE you apply any transformations
For example...
Rectangles becomes the main driver/engine. It's responsible for managing the entities and updating them each cycle. Normally, I'd use some kind of interface that described the functionality that other case might be able to use, but you get the idea
public class Rectangles {
public static void main(String[] args) throws Exception {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
Rectangles game = new Rectangles();
game.play();
}
});
}
public void play() {
Board board = new Board(this);
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(board);
f.pack();
f.setLocation(200, 200);
f.setVisible(true);
Timer timer = new Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
updateRectangles();
board.repaint();
lastTime = System.nanoTime();
}
});
timer.start();
}
public Rectangles() {
rectangle_2 = new Rectangle_2();
rectangles = new ArrayList<Rectangle_2>();
}
protected void updateRectangles() {
boolean first = (lastTime == -1L);
double elapsedTime = System.nanoTime() - lastTime;
elapsedTime = (first ? 0.0f : (float) elapsedTime / 1e9f);
ticks++;
if (ticks <= 1 || ticks % 100 == 0) {
Rectangle_2 rectangle = new Rectangle_2();
rectangles.add(rectangle);
}
rotateRectangles();
moveRectangles(elapsedTime);
for (int i = 0; i < rectangles.size(); i++) {
Rectangle_2 rectangle = rectangles.get(i);
if (rectangle.getX() < -75) {
rectangles.remove(i);
i--;
}
}
}
public void drawRectangles(Graphics2D g) {
for (Rectangle_2 rectangle : rectangles) {
rectangle.drawRectangle(g);
}
}
protected void rotateRectangles() {
for (Rectangle_2 rectangle : rectangles) {
rectangle.rotateRectangle();
}
}
protected void moveRectangles(double elapsedTime) {
for (Rectangle_2 rectangle : rectangles) {
rectangle.move(10 * elapsedTime);
}
}
private long lastTime = -1L;
private Rectangle_2 rectangle_2;
private int ticks = 0;
private ArrayList<Rectangle_2> rectangles;
}
Board becomes nothing more then a surface onto which the entities can be rendered
public class Board extends JPanel {
public Board(Rectangles engine) {
game = engine;
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
game.drawRectangles((Graphics2D) g);
}
private Rectangles game;
}
And Rectangle_2 is a simple container of information which knows how to paint itself when given the chance. You will note the movement and rotation methods just update the state, they do nothing else.
drawRectangle first creates a copy of the supplied Graphics2D context, before it applies it's changes and renders the rectangle, when done, it calls dispose to dispose of the copy
public class Rectangle_2 {
public Rectangle_2() {
x = 0;
y = 200;
rectangle = new Rectangle((int) x, (int) y, 25, 25);
}
public void drawRectangle(Graphics2D g) {
Graphics2D g2 = (Graphics2D) g.create();
g2.rotate(angle, rectangle.getX() + rectangle.getWidth() / 2, rectangle.getY() + rectangle.getHeight() / 2);
g2.setColor(Color.red);
g2.draw(rectangle);
g2.dispose();
}
public void rotateRectangle() {
angle += 0.001;
}
public void move(double elapsedTime) {
x = x + elapsedTime;
rectangle.setLocation((int) x, (int) y);
}
public boolean collides(Rectangle r) {
return r.intersects(rectangle);
}
#Override
public String toString() {
return "Pipe [x = " + x + ", y = " + y + ", rectangle = " + rectangle + "]";
}
public Rectangle getRectangle() {
return rectangle;
}
public double getX() {
return x;
}
private double x;
private double y;
private double angle = 0;
private Rectangle rectangle;
}

How do you create multiple animated components with timer/actionevents with two different time intervals on the same panel?

I need help with a simple animation assignment. It goes as follows.
I have two stop lights on a JPanel and the object is for the two of them to have different time intervals i.e there lights cycle at different times.
Everything works fine if I only have one light at a time. I am relatively new to this but I believe I know the problem.
In the code under this text, I use this several times. I believe my issue occurs in the public void cycle() method in which it just says this.repaint(); I have a feeling that the panel is being repainted at the two different time periods and it gives me a somewhat random light changing instead of a nice cycle.
Is there a way I can have these two components on the same JPanel with a more specific repaint method (maybe a bounding box around the individual light fixtures) or would creating separate panels be a better option (and a little help if that is the case because I understand the basic layouts but have never used them before).
import java.awt.*;
import java.awt.geom.*;
import javax.swing.*;
public class DrawingPanel extends JPanel implements Lighter
{
// instance variables
private final int INTERVAL1 = 2000;
private final int INTERVAL2 = 5000;
private TrafficLight _light1, _light2;
private LightTimer _timer1,_timer2;
/**
* Constructor for objects of class DrawingPanel
*/
public DrawingPanel()
{
// initialise instance variables
super();
this.setBackground(Color.CYAN);
_light1 = new TrafficLight(50,50);
_light2 = new TrafficLight(200,50);
_timer1 = new LightTimer(INTERVAL1,this);
_timer2 = new LightTimer(INTERVAL2,this);
_timer1.start();
_timer2.start();
}
public void cycle(){
_light1.cycle();
_light2.cycle();
this.repaint();
}
public void paintComponent(Graphics pen)
{
super.paintComponent(pen);
Graphics2D aBetterPen = (Graphics2D)pen;
_light1.fill(aBetterPen);
_light2.fill(aBetterPen);
}
}

Running two timers in the fashion is achievable. Personally, I would write a "signal" class that controls a single light with it's own timing and painting routines, but that's not what you've asked.
What you need to do is maintain some kind of state variable for each signal and update them separately.
You would then need to modify the paint code to detect these states and take appropriate actions...for example
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.geom.Ellipse2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class TestBlink {
public static void main(String[] args) {
new TestBlink();
}
public TestBlink() {
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 Timer blink1;
private Timer blink2;
private boolean light1 = false;
private boolean light2 = false;
public TestPane() {
blink1 = new Timer(250, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
light1 = !light1;
repaint();
}
});
blink2 = new Timer(1000, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
light2 = !light2;
repaint();
}
});
blink1.start();
blink2.start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
int radius = 20;
int x = (getWidth() - (radius * 2)) / 2;
int y = (getHeight() - (radius * 2)) / 2;
Ellipse2D signal1 = new Ellipse2D.Float(x, y, radius, radius);
Ellipse2D signal2 = new Ellipse2D.Float(x + radius, y, radius, radius);
g2d.setColor(Color.RED);
g2d.draw(signal1);
if (light1) {
g2d.fill(signal1);
}
g2d.setColor(Color.GREEN);
g2d.draw(signal2);
if (light2) {
g2d.fill(signal2);
}
g2d.dispose();
}
}
}
Updated
A better solution (as I stated earlier) would be to contain all the logic for a single sequence in a single class. This isolates the painting and allows you to change the individual nature each sequence.
For example...
This is a simple example which uses a fixed rate of change, so each light gets the same about of time...
public class TraficLight01 extends JPanel {
public static final int RADIUS = 20;
private Timer timer;
private int state = 0;
public TraficLight01() {
timer = new Timer(500, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
state++;
if (state > 2) {
state = 0;
}
repaint();
}
});
timer.start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(RADIUS, (RADIUS + 1) * 3);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
int radius = 20;
Ellipse2D light = new Ellipse2D.Float(0, 0, RADIUS, RADIUS);
int x = (getWidth() - radius) / 2;
int y = ((getHeight()- (radius * 3)) / 2) + (radius * 2);
Color color[] = new Color[]{Color.RED, Color.YELLOW, Color.GREEN};
for (int index = 0; index < color.length; index++) {
g2d.translate(x, y);
g2d.setColor(color[index]);
g2d.draw(light);
if (state == index) {
g2d.fill(light);
}
g2d.translate(-x, -y);
y -= radius + 1;
}
g2d.dispose();
}
}
Or you provide a variable interval for each light...
public static class TraficLight02 extends JPanel {
public static final int RADIUS = 20;
private Timer timer;
private int state = 0;
// Green, Yellow, Red
private int[] intervals = new int[]{3000, 500, 3000};
public TraficLight02() {
timer = new Timer(intervals[0], new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
timer.stop();
state++;
if (state > 2) {
state = 0;
}
timer.setInitialDelay(intervals[state]);
repaint();
timer.restart();
}
});
timer.start();
timer.setRepeats(false);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(RADIUS, (RADIUS + 1) * 3);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
int radius = 20;
Ellipse2D light = new Ellipse2D.Float(0, 0, RADIUS, RADIUS);
int x = (getWidth() - radius) / 2;
int y = ((getHeight()- (radius * 3)) / 2) + (radius * 2);
Color color[] = new Color[]{Color.GREEN, Color.YELLOW, Color.RED};
for (int index = 0; index < color.length; index++) {
g2d.translate(x, y);
g2d.setColor(color[index]);
g2d.draw(light);
if (state == index) {
g2d.fill(light);
}
g2d.translate(-x, -y);
y -= radius + 1;
}
g2d.dispose();
}
}
It wouldn't take much to change these two concepts to seed them with variable intervals via a setter method.
Equally, you could use three Timers, each time one fires, you would simply start the next one. This way you could define a chain of timers, each one firing at different intervals after the completion of it's parent...

As a Note, your comment
it gives me a somewhat random light changing instead of a nice cycle.
What are you expecting it to look like?
With the Time intervals you have set it may appear somewhat random but it is actually working ie your intervals would work like this (well my assumptions of what the Interval variable are for)
Time(s) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Light1 ON OFF ON OFF ON OFF ON OFF
Light2 ON OFF ON

How to make an image move from left to right in Java

so far i have created the class below, however, now i would like to insert a code to make the image slide from left to right and right to left. I would normally use the Sliding platform however it doesn't work when i try to implement it. I am still a beginner in java so i am grateful for your help.
This is the code of my Java Class:
package game;
import city.soi.platform.*;
public class Enemy extends Body implements CollisionListener{
private Game game ;
public Enemy(Game g){
super(g.getWorld(), new PolygonShape(-27.0f,25.0f, -27.0f,-24.0f, 25.0f,-24.0f, 26.0f,25.0f, -27.0f,25.0f));
setImage(new BodyImage("images/enemy.png"));
g.getWorld().addCollisionListener(this);
game = g;
}
public void collide(CollisionEvent e) {
if (e.getOtherBody() == game.getPlayer()){
game.getPlayer().subtractFromScore(75);
System.out.println("You have just lossed 75 Points! Current Score = " + game.getPlayer().getScore());
this.destroy();
}
}
}
Just to be clear i would like everyone i include this class onto a platform it moves from left to right.
Many Thanks,
Moe

This will depend a lot on what you individual requirements, but the basic concepts will remain the same.
Any type of animation in Swing must be executed in such away that it does not block the Event Dispatching Thread. Any blocking action on the EDT will prevent any repaint request (amongst other things) from been processed.
This simple example uses a javax.swing.Timer that ticks every 40 milliseconds or so (about 25 fps) and updates the position of a small "ball"
More complex iterations would require a dedicated Thread. This makes the whole process far more complex as
You should never update/create/modify/change any UI component (or property that the UI may require to perform painting) from any thread other then the EDT
You don't control the paint process. This means a repaint may occur at anytime and if you are modifying any property/object that the paint process requires to render the state of the game, it could cause inconsistencies.
.
public class SimpleBouncyBall {
public static void main(String[] args) {
new SimpleBouncyBall();
}
public SimpleBouncyBall() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (Exception ex) {
}
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new CourtPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class CourtPane extends JPanel {
private Ball ball;
private int speed = 5;
public CourtPane() {
Timer timer = new Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
Rectangle bounds = new Rectangle(new Point(0, 0), getSize());
if (ball == null) {
ball = new Ball(bounds);
}
speed = ball.move(speed, bounds);
repaint();
}
});
timer.setRepeats(true);
timer.setCoalesce(true);
timer.start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(100, 100);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (ball != null) {
Graphics2D g2d = (Graphics2D) g.create();
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
Point p = ball.getPoint();
g2d.translate(p.x, p.y);
ball.paint(g2d);
g2d.dispose();
}
}
}
public class Ball {
private Point p;
private int radius = 12;
public Ball(Rectangle bounds) {
p = new Point();
p.x = 0;
p.y = bounds.y + (bounds.height - radius) / 2;
}
public Point getPoint() {
return p;
}
public int move(int speed, Rectangle bounds) {
p.x += speed;
if (p.x + radius >= (bounds.x + bounds.width)) {
speed *= -1;
p.x = ((bounds.x + bounds.width) - radius) + speed;
} else if (p.x <= bounds.x) {
speed *= -1;
p.x = bounds.x + speed;
}
p.y = bounds.y + (bounds.height - radius) / 2;
return speed;
}
public void paint(Graphics2D g) {
g.setColor(Color.RED);
g.fillOval(0, 0, radius, radius);
}
}
}

Java - MouseListener Action Event in paintComponent

Here i have a code which draws a rectangle on the mouseClicked position using the paintComponent.I can get the output message but anything related to graphics and .draw() wont work.
Code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public final class testclass extends JFrame {
static JPanel p;
Timer t;
int x = 1;
int y = 1;
int xspeed = 1;
int yspeed = 1;
public testclass() {
initComponents();
this.setBounds(100, 300, 500, 500);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
t.start();
this.add(p);
}
public void initComponents() {
final ActionListener action = new ActionListener() {
public void actionPerformed(ActionEvent evt) {
System.out.println("Hello!");
p.repaint();
}
};
t = new Timer(50, action);
p = new JPanel() {
public void paintComponent(Graphics g) {
super.paintComponent(g);
final Graphics2D gD = (Graphics2D) g;
moveBALL();
gD.drawOval(x, y, 25, 25);
p.addMouseListener(new MouseListener() {
#Override
public void mouseReleased(MouseEvent e) {
System.out.println("a");
}
#Override
public void mousePressed(MouseEvent e) {
System.out.println("b");
}
#Override
public void mouseExited(MouseEvent e) {
System.out.println("c");
}
#Override
public void mouseEntered(MouseEvent e) {
System.out.println("d");
}
#Override
public void mouseClicked(MouseEvent e) {
gD.drawRect(e.getX(), e.getY(), 10, 60);
gD.setColor(Color.green);
System.out.println("clicked");
}
});
}
void moveBALL() {
x = x + xspeed;
y = y + yspeed;
if (x < 0) {
x = 0;
xspeed = -xspeed;
} else if (x > p.getWidth() - 20) {
x = p.getWidth() - 20;
xspeed = -xspeed;
}
if (y < 0) {
y = 0;
yspeed = -yspeed;
} else if (y > p.getHeight() - 20) {
y = p.getHeight() - 20;
yspeed = -yspeed;
}
}
};
}
public static void main(String args[]) {
EventQueue.invokeLater(new Runnable() {
public void run() {
new testclass().setVisible(true);
p.setBackground(Color.WHITE);
}
});
}
}
What is the proper way to implement a mouseListener() in this program?
Thanks.

Some suggestions on current code:
Watch class naming scheme i.e testclass should be TestClass or even better Test (but thats nit picking). All class names begin with capital letter and each new word thereafter is capitalized.
Dont extend JFrame unnecessarily.
Dont call setBounds on JFrame rather use appropriate LayoutManager and/or override getPreferredSize() of JPanel and return dimensions which fits its content.
Always call pack() on JFrame before setting it visible (taking above into consideration).
Use MouseAdapter vs MouseListener
Dont call moveBall() in paintComponent rather call it in your Timer which repaints the screen, not only slightly better design but we also should not do possibly long running tasks in paint methods.
As for your problem I think your logic is a bit skewed.
One approach would see the Rectangle (or Rectangle2D) get replaced by its own custom class (which will allow us to store attributes like color etc). Your ball would also have its own class which has the method moveBall() and its attributes like x and y position etc. On every repaint() your JPanel would call the method to move the ball, the JPanel itself could wrap the moveBall() in its own public method which we could than call from the timer which repaints the screen.
Here is an example of your code with above fixes implemented (please analyze it and if you have any questions let me know):
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import javax.swing.*;
public class Test {
private MyPanel p;
private Timer t;
public Test() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
initComponents();
frame.add(p);
frame.pack();
frame.setVisible(true);
t.start();
}
private void initComponents() {
final ActionListener action = new ActionListener() {
#Override
public void actionPerformed(ActionEvent evt) {
p.moveEntities();//moves ball etc
p.repaint();
}
};
t = new Timer(50, action);
p = new MyPanel();
p.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
p.addEntity(e.getX(), e.getY(), 10, 50, Color.GREEN);
System.out.println("clicked");
}
});
p.setBackground(Color.WHITE);
}
public static void main(String args[]) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new Test();
}
});
}
}
class MyPanel extends JPanel {
int width = 300, height = 300;
ArrayList<MyRectangle> entities = new ArrayList<>();
MyBall ball = new MyBall(10, 10, 25, 25, Color.RED, width, height);
void addEntity(int x, int y, int w, int h, Color c) {
entities.add(new MyRectangle(x, y, w, h, c));
}
void moveEntities() {
ball.moveBALL();
}
#Override
protected void paintComponent(Graphics grphcs) {
super.paintComponent(grphcs);
Graphics2D g2d = (Graphics2D) grphcs;
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setColor(ball.getColor());
g2d.fillOval((int) ball.x, (int) ball.y, (int) ball.width, (int) ball.height);
for (MyRectangle entity : entities) {
g2d.setColor(entity.getColor());
g2d.fillRect((int) entity.x, (int) entity.y, (int) entity.width, (int) entity.height);
}
}
#Override
public Dimension getPreferredSize() {
return new Dimension(width, height);
}
}
class MyRectangle extends Rectangle2D.Double {
Color color;
public MyRectangle(double x, double y, double w, double h, Color c) {
super(x, y, w, h);
color = c;
}
public void setColor(Color color) {
this.color = color;
}
public Color getColor() {
return color;
}
}
class MyBall extends Ellipse2D.Double {
int xspeed = 1;
int yspeed = 1;
Color color;
private final int maxWidth;
private final int maxHeight;
public MyBall(double x, double y, double w, double h, Color c, int maxWidth, int maxHeight) {
super(x, y, w, h);
color = c;
this.width = w;//set width and height of Rectangle2D
this.height = h;
//set max width and height ball can move
this.maxWidth = maxWidth;
this.maxHeight = maxHeight;
}
public void setColor(Color color) {
this.color = color;
}
public Color getColor() {
return color;
}
void moveBALL() {
x = x + xspeed;
y = y + yspeed;
if (x < 0) {
x = 0;
xspeed = -xspeed;
} else if (x > maxWidth - ((int) getWidth() / 2)) {// i dont like hard coding values its not good oractice and resuaibilty is diminshed
x = maxWidth - ((int) getWidth() / 2);
xspeed = -xspeed;
}
if (y < 0) {
y = 0;
yspeed = -yspeed;
} else if (y > maxHeight - ((int) getHeight() / 2)) {
y = maxHeight - ((int) getHeight() / 2);
yspeed = -yspeed;
}
}
}

First of all the paint component is called every time swing needs to redraw the component.
And you are adding a new instance of mouse listener to the panel every time the paint is called.
Just move the line
p.addMouseListener(new MouseListener() {...}
out of the paint component, preferably after the initialization of the panel.
default template is
JPanel p = new JPanel(){
#Override
public void paintComponent(Graphics g) {
}
};
p.addMouseListener(new MouseListener() or new MouseAdapter()
//Your overridden methods
});
Hope this helps.