Head First Java的Java Beatbox中的ArrayIndexOutOfBoundsException

Question

我一直在尝试从头开始的Java的Beatbox代码，但收到如下错误。 我尝试过在线搜索问题，但找不到任何问题。

码

package beatbox;

import java.awt.*;
import javax.swing.*;
import javax.sound.midi.*;
import java.util.*;
import java.awt.event.*;

public class BeatBox {

JPanel mainPanel;
ArrayList<JCheckBox> checkboxList;
Sequencer sequencer;
Sequence sequence;
Track track;
JFrame theFrame;

String[] instrumentNames = {"Bass Drum","Closed Hi hat",
        "Opoen HI hat","acopustic snare","crash cymbal",
        "hand clap","high tom","hi bongo","maracas",
        "whistle","low conga","cowbell","vibrasalp",
        "low mid tom","high agogo","open hi conga"};
int [] instruments = {35,42,46,38,49,39,50,70,72,64,56,58,47,67,63};


public static void main (String[] args)
{
    new BeatBox().buildGUI();
}

public void buildGUI()
{
    theFrame = new JFrame("Cyber BeatBox");
    theFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    BorderLayout layout = new BorderLayout();
    JPanel background = new JPanel (layout);
    background.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));

    checkboxList = new ArrayList <>();
    Box buttonBox = new Box(BoxLayout.Y_AXIS);

    JButton start = new JButton("Start");
    start.addActionListener(new MyStartListener());
    buttonBox.add(start);

    JButton stop = new JButton("stop");
    stop.addActionListener(new MyStopListener());
    buttonBox.add(stop);

    JButton upTempo = new JButton("Tempo up");
    upTempo.addActionListener(new MyUpTempoListener());
    buttonBox.add(upTempo);

    JButton downTempo = new JButton("Tempo Down");
    downTempo.addActionListener(new MyDownTempoListener());
    buttonBox.add(downTempo);

    Box nameBox = new Box(BoxLayout.Y_AXIS);

    for (int i = 0; i<16;i++)
    {
        nameBox.add(new Label(instrumentNames[i]));
    }

    background.add(BorderLayout.EAST, buttonBox);
    background.add(BorderLayout.WEST, nameBox);

    theFrame.getContentPane().add(background);

    GridLayout grid = new GridLayout (16,16);
    grid.setVgap(1);
    grid.setHgap(2);
    mainPanel = new JPanel (grid);
    background.add(BorderLayout.CENTER,mainPanel);

    for (int i = 0; i<256;i++)
    {
        JCheckBox c = new JCheckBox();
        c.setSelected(false);
        checkboxList.add(c);
        mainPanel.add(c);       
    }

    setUpMidi();
    theFrame.setBounds(50,50,300,300);
    theFrame.pack();
    theFrame.setVisible(true);

}//clsoe GUI metod

public void setUpMidi()
{
    try
    {
        sequencer = MidiSystem.getSequencer();
        sequencer.open();
        sequence = new Sequence(Sequence.PPQ,4);
        track = sequence.createTrack();
        sequencer.setTempoInBPM(120);
    }
    catch (MidiUnavailableException | InvalidMidiDataException e){e.printStackTrace();}
}


//important code beigns

public void buildTrackAndStart()
{
    int[] trackList = null;
    sequence.deleteTrack(track);
    track = sequence.createTrack();

    for (int i = 0; i<16; i++)
    {
        trackList = new int[16];
        int key = instruments[i];
        for(int j=0;j<16;j++)
        {
            JCheckBox jc = (JCheckBox) checkboxList.get(j+(16*i));

            if (jc.isSelected())
                {
                    trackList[j] = key;
                }
            else
                {
                    trackList[j] = 0;
                }
        }

        makeTracks(trackList);
        track.add(makeEvent(176,1,127,0,16));   
    }

    track.add(makeEvent(192,9,1,0,15));
    try
    {
        sequencer.setSequence(sequence);
        sequencer.setLoopCount(Sequencer.LOOP_CONTINUOUSLY);
        sequencer.start();
        sequencer.setTempoInBPM(120);
    }

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

} //close buioldtrack and strart method


public class MyStartListener implements ActionListener
{
            @Override
    public void actionPerformed(ActionEvent a)
    {
        buildTrackAndStart();       
    }
}

public class MyStopListener implements ActionListener
{
            @Override
    public void actionPerformed(ActionEvent a)
    {
        sequencer.stop();       
    }
}

public class MyUpTempoListener implements ActionListener
{
            @Override
    public void actionPerformed(ActionEvent a)
    {
        float tempoFactor = sequencer.getTempoFactor();
        sequencer.setTempoFactor((float)(tempoFactor * 1.03));
    }
}

public class MyDownTempoListener implements ActionListener
{
            @Override
    public void actionPerformed(ActionEvent a)
    {
        float tempoFactor = sequencer.getTempoFactor();
        sequencer.setTempoFactor((float)(tempoFactor * 0.97));
    }
}


public void makeTracks(int[] list)
{
    for (int i = 0; i < 16; i++)
    {
        int key = list[i];

        if(key !=0)
        {
            track.add(makeEvent(144,9,key,100,i));
            track.add(makeEvent(128,9,key,100,i+1));
        }
    }
}


public 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;
}
}

错误

WARNING: Could not open/create prefs root node Software\JavaSoft\Prefs at root 0x80000002. Windows RegCreateKeyEx(...) returned error code 5.
Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 15
    at beatbox.BeatBox.buildTrackAndStart(BeatBox.java:119)
    at beatbox.BeatBox$MyStartListener.actionPerformed(BeatBox.java:157)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.java:6535)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
    at java.awt.Component.processEvent(Component.java:6300)
    at java.awt.Container.processEvent(Container.java:2236)
    at java.awt.Component.dispatchEventImpl(Component.java:4891)
    at java.awt.Container.dispatchEventImpl(Container.java:2294)
    at java.awt.Component.dispatchEvent(Component.java:4713)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
    at java.awt.Container.dispatchEventImpl(Container.java:2280)
    at java.awt.Window.dispatchEventImpl(Window.java:2750)
    at java.awt.Component.dispatchEvent(Component.java:4713)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
    at java.awt.EventQueue.access$500(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:709)
    at java.awt.EventQueue$3.run(EventQueue.java:703)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
    at java.awt.EventQueue$4.run(EventQueue.java:731)
    at java.awt.EventQueue$4.run(EventQueue.java:729)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

BUILD SUCCESSFUL (total time: 23 seconds

Answer 1

instruments数组只有15个成员，因此有效索引为0-14。