Ball Animation in Swing

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The Problem is when I resize the JFrame the animation goes on with it's Pre supplied dimensions for JComponent . Is there a way that I can update my width and height variables as I resize the JFrame, so that the Animation can run along with the new Co-ordinates.

In simpler terms, say the JComponent has initial width = 300 and height = 300, so the BALL moves inside these specified Co-ordinates. Now if I resize my JFrame, the size for the JComponent still remains as is i.e. width = 300 and height = 300, but what I was hoping for, is a way to modify these variables with the present size of the window. Do let me know if I lack something in explaining my issue.

Here is the code that I am using :

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class BallAnimation
{
    private int x;
    private int y;
    private int count;
    private int width;
    private int height;
    private int speedValue;
    private boolean flag;
    /*
     * These variables are used to keep track of 
     * the ball, either it is going LEFT or RIGHT
     * depending on that, we will set the 
     * Co-ordinates.
     */
    private boolean toLeft, toRight;

    private boolean fromTop, fromBottom;

    private Timer timer;

    private JButton button;

    private ActionListener actionTimer; 
    private ActionListener buttonAction;

    public BallAnimation()
    {
        x = y = count = 0;
        flag = toLeft = false;
        toRight = true;
        fromTop = true;
        fromBottom = false;
        speedValue = 5;
    }

    public static void main(String args[])
    {
        Runnable runnable = new Runnable()
        {
            public void run()
            {
                BallAnimation animation = new BallAnimation();
                animation.go();
            }
        };      
        SwingUtilities.invokeLater(runnable);
    }

    public void go()
    {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //JPanel contentPane = new JPanel();

        /*
         * Class Name : 
         * Java Naming Convention says that class names 
         * should be in Pascal Case, i.e. the first
         * letter of the class name should be capitalized
         * and every new word must start with a capitalized 
         * Alphabet.
         * For Example : 
         * public class ClassName{...}
         * ----------------------------------------------------------
         * Variable Name : 
         * Java Naming Convention says that the variable name
         * should be in Camel Case, i.e. the first letter of 
         * the variable name should be small case or _ (underscore)
         * and every new word must start with a capitalized
         * Alphabet.
         * ---------------------------------------------------------
         */
        final MyDraw drawPanel = new MyDraw(0, 0);
        x = drawPanel.getXValue();
        y = drawPanel.getYValue();
        //contentPane.add(drawPanel);

        actionTimer = new ActionListener()
        {
            public void actionPerformed(ActionEvent ae)
            {               
                if (fromTop && !fromBottom && x < width && y < height 
                            && toRight && !toLeft)
                {
                    x += speedValue;
                    y += speedValue;
                }
                else if (fromTop && !fromBottom && x < width && y >= height
                                 && toRight && !toLeft)
                {
                    /*
                     * Since the ball coming from the TOP LEFT Side
                     * touched the BOTTOM of the JPanel.
                     */
                    y -= speedValue;
                    x += speedValue;
                    fromTop = false;
                    fromBottom = true;
                }
                else if (!fromTop && fromBottom && x < width && y <= 0
                                  && toRight && !toLeft)
                {
                    /*
                     * Since the ball coming from BOTTOM LEFT Side
                     * touched the TOP of the JPanel. 
                     */
                    fromTop = true;
                    fromBottom = false;
                    x += speedValue;
                    y += speedValue;
                }
                else if (!fromTop && fromBottom && x < width && y < height
                                  && toRight && !toLeft)
                {
                    x += speedValue;
                    y -= speedValue;
                }
                else if (!fromTop && fromBottom && x >= width && y < height
                                  && toRight && !toLeft)
                {
                    /*
                     * Since the ball coming from the BOTTOM LEFT Side
                     * touched the RIGHT Side of the JPanel.
                     */
                    toRight = false;
                    toLeft = true;
                    x -= speedValue;
                    y -= speedValue;
                }                
                else if (!fromTop && fromBottom && x < width && y <= 0
                                  && !toRight && toLeft)
                {
                    /*
                     * Since the ball coming from the BOTTOM RIGHT Side
                     * touched the Top Side of the JPanel.
                     */
                    fromTop = true;
                    fromBottom = false;
                    x -= speedValue;
                    y += speedValue;
                }
                else if (fromTop && !fromBottom && x <= 0 && y < height
                                 && !toRight && toLeft)
                {
                    /*
                     * Since the ball coming from the TOP RIGHT Side
                     * touched the LEFT Side of the JPanel.
                     */
                    toRight = true;
                    toLeft = false;
                    x += speedValue;
                    y += speedValue;
                }
                else if (fromTop && !fromBottom && x >= width && y < height
                                  && toRight && !toLeft)
                {
                    /*
                     * Since the ball coming from the TOP LEFT Side
                     * touched the RIGHT Side of the JPanel
                     */
                    toRight = false;
                    toLeft = true;
                    x -= speedValue;
                    y += speedValue;
                }
                else if (fromTop && !fromBottom && x < width && y < height
                                  && !toRight && toLeft)
                {
                    x -= speedValue;
                    y += speedValue;
                }
                else if (!fromTop && fromBottom && x <= 0 && y < height
                                  && !toRight && toLeft)
                {
                    /*
                     * Since the ball coming from the BOTTOM RIGHT Side
                     * touched the LEFT Side of the JPanel.
                     */
                    toRight = true;
                    toLeft = false;
                    x += speedValue;
                    y -= speedValue;
                }
                else if (!fromTop && fromBottom && x < width && y < height
                                  && !toRight && toLeft)
                {
                    x -= speedValue;
                    y -= speedValue;
                }
                else if (fromTop && !fromBottom && x < width && y >= height
                                  && !toRight && toLeft)
                {
                    /*
                     * Since the ball coming from the TOP RIGHT Side
                     * touched the BOTTOM Side of the JPanel.
                     */
                    fromTop = false;
                    fromBottom = true;
                    x -= speedValue;
                    y -= speedValue;
                }
                System.out.println("X : " + x);
                System.out.println("Y : " + y);
                System.out.println("Direction is LEFT : " + toLeft);
                System.out.println("Direction is RIGHT : " + toRight);
                System.out.println("Coming from TOP : " + fromTop);
                System.out.println("Coming from BOTTOM : " + fromBottom);
                drawPanel.setXYValues(x, y);
            }
        };

        buttonAction = new ActionListener()
        {
            public void actionPerformed(ActionEvent ae)
            {
                if (!flag)
                {
                    timer.start();
                    button.setText("STOP ANIMATION");
                    flag = true;
                }
                else if (flag)
                {
                    timer.stop();
                    button.setText("START ANIMATION");
                    flag = false;
                }
            }
        };

        button = new JButton("START ANIMATION");
        button.addActionListener(buttonAction);

        frame.getContentPane().add(drawPanel, BorderLayout.CENTER);
        frame.getContentPane().add(button, BorderLayout.PAGE_END);
        frame.setSize(300, 300);
        //frame.pack();
        frame.setVisible(true);        

        timer = new Timer(40, actionTimer);
        width = drawPanel.getWidth() - 30;
        System.out.println("WIDTH : " + width);
        height = drawPanel.getHeight() - 30;    
        System.out.println("HEIGHT : " + height);
    }
    class MyDraw extends JComponent
    {
        private int x;
        private int y;
        private Timer timer;

        public MyDraw(int x, int y)
        {
            this.x = x;
            this.y = y;
        }

        public int getXValue()
        {
            return x;
        }

        public int getYValue()
        {
            return y;
        }

        public void setXYValues(int x, int y)
        {
            this.x = x;
            this.y = y;
            repaint();
        }

        public Dimension getPreferredSize()
        {
            return (new Dimension(300, 300));
        }

        public void paintComponent(Graphics g)
        {
            g.setColor(Color.WHITE);
            g.fillRect(0, 0, getWidth(), getHeight());
            g.setColor(Color.BLUE);
            g.fillOval(x, y, 40, 40);
        }
    }
}

Now that is a whole heapin' helping of code! Try this variant (breaks one or two things, but fixes the main problem). The fix is to base the width/height on the current size of the component.

package test;

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class BallAnimation
{
    private int x;
    private int y;
    private int count;
    //private int drawPanel.getWidth();
    //private int drawPanel.getHeight();
    private int speedValue;
    private boolean flag;
    /*
     * These variables are used to keep track of 
     * the ball, either it is going LEFT or RIGHT
     * depending on that, we will set the 
     * Co-ordinates.
     */
    private boolean toLeft, toRight;

    private boolean fromTop, fromBottom;

    private Timer timer;

    private JButton button;

    private ActionListener actionTimer; 
    private ActionListener buttonAction;

    MyDraw drawPanel;

    public BallAnimation()
    {
        x = y = count = 0;
        flag = toLeft = false;
        toRight = true;
        fromTop = true;
        fromBottom = false;
        speedValue = 5;
    }

    public static void main(String args[])
    {
        Runnable runnable = new Runnable()
        {
            public void run()
            {
                BallAnimation animation = new BallAnimation();
                animation.go();
            }
        };      
        SwingUtilities.invokeLater(runnable);
    }

    public void go()
    {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //JPanel contentPane = new JPanel();

        /*
         * Class Name : 
         * Java Naming Convention says that class names 
         * should be in Pascal Case, i.e. the first
         * letter of the class name should be capitalized
         * and every new word must start with a capitalized 
         * Alphabet.
         * For Example : 
         * public class ClassName{...}
         * ----------------------------------------------------------
         * Variable Name : 
         * Java Naming Convention says that the variable name
         * should be in Camel Case, i.e. the first letter of 
         * the variable name should be small case or _ (underscore)
         * and every new word must start with a capitalized
         * Alphabet.
         * ---------------------------------------------------------
         */
        drawPanel = new MyDraw(0, 0);
        x = drawPanel.getXValue();
        y = drawPanel.getYValue();
        //contentPane.add(drawPanel);

        actionTimer = new ActionListener()
        {
            public void actionPerformed(ActionEvent ae)
            {               
                if (fromTop && !fromBottom && x < drawPanel.getWidth() && y < drawPanel.getHeight() 
                            && toRight && !toLeft)
                {
                    x += speedValue;
                    y += speedValue;
                }
                else if (fromTop && !fromBottom && x < drawPanel.getWidth() && y >= drawPanel.getHeight()
                                 && toRight && !toLeft)
                {
                    /*
                     * Since the ball coming from the TOP LEFT Side
                     * touched the BOTTOM of the JPanel.
                     */
                    y -= speedValue;
                    x += speedValue;
                    fromTop = false;
                    fromBottom = true;
                }
                else if (!fromTop && fromBottom && x < drawPanel.getWidth() && y <= 0
                                  && toRight && !toLeft)
                {
                    /*
                     * Since the ball coming from BOTTOM LEFT Side
                     * touched the TOP of the JPanel. 
                     */
                    fromTop = true;
                    fromBottom = false;
                    x += speedValue;
                    y += speedValue;
                }
                else if (!fromTop && fromBottom && x < drawPanel.getWidth() && y < drawPanel.getHeight()
                                  && toRight && !toLeft)
                {
                    x += speedValue;
                    y -= speedValue;
                }
                else if (!fromTop && fromBottom && x >= drawPanel.getWidth() && y < drawPanel.getHeight()
                                  && toRight && !toLeft)
                {
                    /*
                     * Since the ball coming from the BOTTOM LEFT Side
                     * touched the RIGHT Side of the JPanel.
                     */
                    toRight = false;
                    toLeft = true;
                    x -= speedValue;
                    y -= speedValue;
                }                
                else if (!fromTop && fromBottom && x < drawPanel.getWidth() && y <= 0
                                  && !toRight && toLeft)
                {
                    /*
                     * Since the ball coming from the BOTTOM RIGHT Side
                     * touched the Top Side of the JPanel.
                     */
                    fromTop = true;
                    fromBottom = false;
                    x -= speedValue;
                    y += speedValue;
                }
                else if (fromTop && !fromBottom && x <= 0 && y < drawPanel.getHeight()
                                 && !toRight && toLeft)
                {
                    /*
                     * Since the ball coming from the TOP RIGHT Side
                     * touched the LEFT Side of the JPanel.
                     */
                    toRight = true;
                    toLeft = false;
                    x += speedValue;
                    y += speedValue;
                }
                else if (fromTop && !fromBottom && x >= drawPanel.getWidth() && y < drawPanel.getHeight()
                                  && toRight && !toLeft)
                {
                    /*
                     * Since the ball coming from the TOP LEFT Side
                     * touched the RIGHT Side of the JPanel
                     */
                    toRight = false;
                    toLeft = true;
                    x -= speedValue;
                    y += speedValue;
                }
                else if (fromTop && !fromBottom && x < drawPanel.getWidth() && y < drawPanel.getHeight()
                                  && !toRight && toLeft)
                {
                    x -= speedValue;
                    y += speedValue;
                }
                else if (!fromTop && fromBottom && x <= 0 && y < drawPanel.getHeight()
                                  && !toRight && toLeft)
                {
                    /*
                     * Since the ball coming from the BOTTOM RIGHT Side
                     * touched the LEFT Side of the JPanel.
                     */
                    toRight = true;
                    toLeft = false;
                    x += speedValue;
                    y -= speedValue;
                }
                else if (!fromTop && fromBottom && x < drawPanel.getWidth() && y < drawPanel.getHeight()
                                  && !toRight && toLeft)
                {
                    x -= speedValue;
                    y -= speedValue;
                }
                else if (fromTop && !fromBottom && x < drawPanel.getWidth() && y >= drawPanel.getHeight()
                                  && !toRight && toLeft)
                {
                    /*
                     * Since the ball coming from the TOP RIGHT Side
                     * touched the BOTTOM Side of the JPanel.
                     */
                    fromTop = false;
                    fromBottom = true;
                    x -= speedValue;
                    y -= speedValue;
                }
                System.out.println("X : " + x);
                System.out.println("Y : " + y);
                System.out.println("Direction is LEFT : " + toLeft);
                System.out.println("Direction is RIGHT : " + toRight);
                System.out.println("Coming from TOP : " + fromTop);
                System.out.println("Coming from BOTTOM : " + fromBottom);
                drawPanel.setXYValues(x, y);
            }
        };

        buttonAction = new ActionListener()
        {
            public void actionPerformed(ActionEvent ae)
            {
                if (!flag)
                {
                    timer.start();
                    button.setText("STOP ANIMATION");
                    flag = true;
                }
                else if (flag)
                {
                    timer.stop();
                    button.setText("START ANIMATION");
                    flag = false;
                }
            }
        };

        button = new JButton("START ANIMATION");
        button.addActionListener(buttonAction);

        frame.getContentPane().add(drawPanel, BorderLayout.CENTER);
        frame.getContentPane().add(button, BorderLayout.PAGE_END);
        frame.setSize(300, 300);
        //frame.pack();
        frame.setVisible(true);        

        timer = new Timer(40, actionTimer);
        System.out.println("WIDTH : " + drawPanel.getWidth());
        System.out.println("HEIGHT : " + drawPanel.getHeight());
    }
    class MyDraw extends JComponent
    {
        private int x;
        private int y;
        private Timer timer;

        public MyDraw(int x, int y)
        {
            this.x = x;
            this.y = y;
        }

        public int getXValue()
        {
            return x;
        }

        public int getYValue()
        {
            return y;
        }

        public void setXYValues(int x, int y)
        {
            this.x = x;
            this.y = y;
            repaint();
        }

        public Dimension getPreferredSize()
        {
            return (new Dimension(300, 300));
        }

        public void paintComponent(Graphics g)
        {
            g.setColor(Color.WHITE);
            g.fillRect(0, 0, getWidth(), getHeight());
            g.setColor(Color.BLUE);
            g.fillOval(x, y, 40, 40);
        }
    }
}

WindowEvent; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; public class BounceThread { public static void main(String[]  Ball Animation in Swing. Ask Question Asked 7 years, 9 months ago. so the BALL moves inside these specified Co-ordinates. Now if I resize my JFrame,

just simply need to addHierarchyBoundsListener(...), to your MyDraw object, i.e. drawPanel , like as explained below :

private HierarchyBoundsListener boundsListener = 
                                new HierarchyBoundsListener()
{
    public void ancestorMoved(HierarchyEvent he)
    {
    }

    public void ancestorResized(HierarchyEvent he)
    {
        JComponent component = (JComponent) he.getComponent();
        width = component.getWidth() - 30;
        height = component.getHeight() - 30;
    }
};

And to add this to your drawPanel object, you be doing :

drawPanel.addHierarchyBoundsListener(boundsListener);

We set our custom JPanel as the content pane for the JFrame . The UI codes are run in the Event Dispatcher Thread (EDT), via javax.swing.SwingUtilities. The King Of Swing At His Best | Anderson Takes Brilliant 7-43 v New Zealand 2008 - Full Highlights - Duration: 6:18. England & Wales Cricket Board 6,075,978 views 6:18

I expect you just need to bind some variety of listener (WindowEventListener?) to the JFrame, so that width and height are updated whenever the window dimensions change.

See an example of a bouncing ball, created in Java and rendered with the Graphics API. Full Duration: 0:09 Posted: Dec 22, 2010 Learn the basics of the golf swing in these photo animations. 9 Swing Basics In GIF Format. you're hitting the sand just behind the ball--so you need to make a big swing back and through

Bouncing Ball example import java.awt.event. JFrame; import javax.swing.​Timer; public class Ball { // execute application public static void main( String args​[] )  Ball and pendulum animation. This feature is not available right now. Please try again later.

JFrame; import javax.swing.JPanel; /** * Shows an animated bouncing ball. * * @​version 1.33 2007-05-17 * @author Cay Horstmann */ public class Bounce  In this video we show you how to play cricket by gripping the ball for the perfect in-swing. For loads more handy how-to’s and the latest trending videos hea

File: animation/bb/BBDemo.java // Description: Illustrates animation with a ball button, // Author: Fred Swartz // Date: February 2005 import javax.swing. When the ball hits the right wall, the horizontal speed will change to -1, which means x will decrease each time. You can also change the starting values to 2 or 3 to make the ball go faster.

Comments
  • You know that your massive amount of if logic could be compressed into like 1/4 that size, and far less code, right? Making it use x and y velocities (which could be negative) would eliminate the boolean flags, turn all of the movement code into x+=xVel;y+=yVel;, and then you're just left with the out-of-bounds checking, which pushes the ball back within bounds, and inverts the relevant velocity.
  • @zebediah49 : May you please ellaborate that logic thingy to me a bit more in your answer :-)
  • It's around a 7 year old piece of code, so the graphics handling is rather deprecated. None the less, the control and wall logic is standard. It's as long as it is because it has both solid (bounce) and periodic (!bounce) boundary conditions. pastebin.com/UT8fyAaB
  • during resize of parent must be Swing Timer inactive, or to held last known Dimension +1
  • You might also enjoy this KineticModel, which uses a ComponentListener.
  • Sorry for the late reply, I liked this answer though (+1 for that), made things worked for me, but as pointed out by @zebediah49 , my code is crap, as far as logic is concern, so seems like adding function call to it will make it worse, along with the condition check. Thankyou for the kind help on this question :-)
  • Today, I changed the logic part of my program, and seems like what you had told in your answer, works too well that no Listener sort of thing is needed. What previously I was doing is checking both x and y together, so which led to too much condition check. I separated the two, which resulted in few lines of check, along with your advice worked flawlessly :-) Thankyou for that :-)
  • "changed the logic part of my program" Excellent! Glad to see you took zebediah49's advice (to refactor the logic). :)
  • Yeah, I learned from everywhere :-) , to focus on my logic part from zebediah49, more info about ball thingy from @trashgod and obviously, your suggestion as well, all worked wonders at the end for my small application :-)
  • "I learned from everywhere" Everywhere is great. I'll often do a quick Google & end up at 3 separate threads at SO, getting tidbits from each. ;)
  • This did made my day, adding HierarchyBoundsListener. Thankyou for the kind help :-)
  • No, it is better to base the width/height on the current size of the component, as seen in my variant.
  • I don't necessarily disagree, but I'm curious why it's better to fetch it every time you use it? (Also, why not assign it to a local variable, instead of calling it every time?)
  • It is minimal expense to call for the current size, and as the OP noted, the current version does not work when resized. It might be possible to implement the update of the size using a listener, but it seems a kludgy hack compared to querying the size when it is needed.
  • @zebediah49 : Thankyou for pointing out that my code is crap, +1 for that :-) , just it's my first painting thingy, so never bothered that much on it, except for the task in hand which is painting :-) . Thankyou for your kind help on this .