Bouncing Images Example

package bouncer;

/* NOTE: requires MyImage.java */

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;



public class BouncingImages extends JFrame implements ActionListener {

    public static void main(String[] args) {
        new BouncingImages();
    }


    /* These are the width and height of the DrawingPanel NOT the whole JFrame.
    Bouncing off walls will not work properly if it's the JFrame size */
    static final int WINW = 1000;
    static final int WINH = 800;

    JPanel buttonPanel = new JPanel();
    AnimationPanel animationPanel;
    ArrayList<MyImage> imageList = new ArrayList<MyImage>();
    AnimationThread thread;
    private volatile boolean stopRequested = false; //maybe should use AtomicBoolean

    BouncingImages() {

        //set up button panel
        JButton btnStart = new JButton("Start");
        JButton btnStop  = new JButton("Stop");
        JButton btnExit  = new JButton("Exit");
        btnStart.addActionListener(this);
        btnStop.addActionListener(this);
        btnExit.addActionListener(this);
        buttonPanel.add(btnStart);
        buttonPanel.add(btnStop);
        buttonPanel.add(btnExit);

        animationPanel = new AnimationPanel();

        //setup JFrame
        //this.setExtendedState(JFrame.MAXIMIZED_BOTH); //If we use this, then we need to determine the dimensions of the JPanel before we start drawing
        // this.setUndecorated(true);
        this.add(buttonPanel, BorderLayout.SOUTH);
        this.add(animationPanel);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.pack(); //since the JPanel is controlling the size, we need pack() here.
        this.setLocationRelativeTo(null);   //after pack();
        this.setVisible(true);
    }

    void startAnimation() {
        //this doesn't restart the thread if it terminates
        if (thread == null) {
            thread = new AnimationThread ();
            stopRequested = false;
            thread.start();
        }
        //System.out.println("thread is " + thread.toString());

        //this will "restart" the thread!
        if (thread.getThreadGroup() == null) {
            thread = new AnimationThread ();
            stopRequested = false;
            thread.start();
        }

    }

    //two different versions here as I was testing how to stop threads properly
    void stopAnimation1(){
        stopRequested = true;
    }

    void stopAnimation2(){
        thread.interrupt();
        //System.out.println(thread.isInterrupted());
    }

    void addImage()  {
        imageList.add(new MyImage("fish.jpeg"));
    }

    void moveAllImages() {
        for (MyImage image : imageList) {
            image.moveImage();
        }
    }


    //ActionListener for Buttons
    @Override
    public void actionPerformed(ActionEvent e) {
        if (e.getActionCommand().equals("Start")) {
            addImage();
            startAnimation();
        }
        if (e.getActionCommand().equals("Stop")) {
            stopAnimation2();
        }
        if (e.getActionCommand().equals("Exit")) {
            System.exit(0);
        }
    }

    //This class does drawing graphics and nothing else
    class AnimationPanel extends JPanel {

        AnimationPanel() {
            this.setBackground(Color.BLACK);
            this.setPreferredSize(new Dimension(WINW, WINH));
        }


        @Override
        public void paintComponent(Graphics g){
            super.paintComponent(g);
            for (MyImage im : imageList) {
                g.drawImage(im.image, im.x, im.y, im.width, im.height,null);
            }
        }
    }

    /* NOTE: I'm not that experienced with threads, preferring to use timers. A Swing Timer would work perfectly for this program
     * Quote: "Starting from Java 5 it is not a good idea to work with Threads directly.
     * You should rather use Executor framework and choose an execution policy depending on your requirements."
     */
    private class AnimationThread extends Thread {

        public void run() {
            run2B(); //here we can test different methods
        }

        //this version stops the thread using a flag and break. (use stopAnimation1())
        public void run1() {
            while (true) {

                //everything in the main game loop goes here
                moveAllImages();
                //collide_images()
                animationPanel.repaint();

                try {
                    this.sleep(5);
                } catch (InterruptedException e) {}

                if(stopRequested) break;
            }

        }

        //this version stops the thread using an interrupt and break (use stopAnimation2())
        public void run2A() {
            while (true) {
                moveAllImages();
                //collide_images()
                animationPanel.repaint();

                try {
                    this.sleep(5);
                } catch (InterruptedException e) {
                    System.out.println("interrupted");
                    break;
                }
            }
        }

        //this version stops the thread using interrupt only (use stopAnimation2())
        public void run2B() {
            while ( ! thread.isInterrupted() ) {  // or     //while (! Thread.currentThread().isInterrupted() ) {
                moveAllImages();
                //collide_images()
                animationPanel.repaint();

                try {
                    this.sleep(5);
                } catch (InterruptedException e) {
                    System.out.println("interrupted");
                    thread.interrupt(); //catching the exception seems to clear it.
                }
            }
        }
    }
}