java - 为每个事件创建非随机形状

Question

我一直在使用java中的ArrayList创建矩形等形状。我试图让矩形一次出现在面板中，然后慢慢构建一个实际图像。我已经没有问题让他们出现并保持随机的位置（位置，大小，颜色）......但是当我试图使这些rects静态...它们都崩溃了。欢迎提出建议。

Full code so far below:

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.List;
import java.awt.Rectangle;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

import javax.sound.midi.ControllerEventListener;
import javax.sound.midi.MidiEvent;
import javax.sound.midi.MidiSystem;
import javax.sound.midi.Sequence;
import javax.sound.midi.Sequencer;
import javax.sound.midi.ShortMessage;
import javax.sound.midi.Track;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class GraphicMusicPlayer
                implements ControllerEventListener {
    static JFrame f = new JFrame("Graphic Music");
    static MyDrawPanel myPanel;


    @Override
    public void controlChange(ShortMessage event) {
        // TODO Auto-generated method stub

    }

    public static void main(String[] args) {
        GraphicMusicPlayer mini = new GraphicMusicPlayer();
        mini.go();
        // TODO Auto-generated method stub

    }
    public void setUpGui() {
        // Create the panel within the frame
        myPanel = new MyDrawPanel();
        f.setContentPane(myPanel);
        f.setBounds(700, 700, 800, 800);
        f.setVisible(true);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    public void go() {
        setUpGui();

        try {
            // Make and open a sequencer.
            Sequencer sequencer = MidiSystem.getSequencer();
            sequencer.open();

            // Register for events. 127 is the event.
            sequencer.addControllerEventListener(myPanel, new int[] {93});
            Sequence seq = new Sequence(Sequence.PPQ, 4);
            Track track = seq.createTrack();

            int r = 0;

            int[] tonesList = new int[] {
                            65, 64, 65, 64, 65, 60, 63, 61,
                            58,65, 64, 65, 64, 65, 60, 63, 61,
                            58};

            for (int i = 0; i < 18; i +=1) {
                r = tonesList[i];
                if (r>0){

                track.add(makeEvent(144,5,r,93,i));//144 = NOTE_ON
                track.add(makeEvent(176,5,93,125,i));//176 = get event
                track.add(makeEvent(128,5,r,46,i+1));//128 = NOTE_OFF
            }//end loop

            sequencer.setSequence(seq);
            sequencer.setTempoInBPM(30);
            sequencer.start();

            }
        }
            catch (Exception ex) {ex.printStackTrace();}

    }
    public static MidiEvent makeEvent(int comd, int chan, int one, int two, int tick) {

        MidiEvent event = null;
        try {
            ShortMessage a = new ShortMessage();
            a.setMessage(comd, chan, one, two);
            event = new MidiEvent(a, tick);
        } catch (Exception e) { }
        return event;
    }
     @SuppressWarnings("serial")
    class MyDrawPanel extends JPanel implements ControllerEventListener {

            boolean msg = false;

            ArrayList<Rectangle> rectangleList = new ArrayList<Rectangle>();
            Map<Rectangle, Color> rectangleColors = new HashMap<Rectangle, Color>();
            public void addRectangle(Rectangle rect){
                rectangleList.add(rect);
            }

            public void controlChange(ShortMessage event) {
                msg  = true;
                repaint();
            }

            public void paintComponent(Graphics g) {
                super.paintComponent(g);
                setBackground(Color.BLACK);


                while (msg) {

                Graphics2D g2 = (Graphics2D) g;
                int red = (int) (Math.random() * 250);
                int green = (int) (Math.random() * 250);
                int blue = (int) (Math.random() * 250);
                Color rcolor = new Color(red, green, blue);
                int x = (int) (Math.random() * 750);
                int y = (int) (Math.random() * 750);
                int width = (int) (Math.random() * 100);
                int height = (int) (Math.random() * 100);

                Rectangle nextRect = new Rectangle(x,y,width,height);
                rectangleList.add(nextRect);
                g.setColor(rcolor);
                rectangleColors.put(nextRect, rcolor);


                //paint all of the rectangles
                for (Rectangle rect : rectangleList){

                    Color rectColor = rectangleColors.get(rect);
                    g.setColor(rectColor);
                    // Fill the rectangle with the rectangle color
                    g2.fill(rect);

                }
                msg = false;
            }

        }
     }
}