我一直在尝试使用head first java中的beatbox代码，但收到如下错误。我试过在线搜索问题，但找不到任何问题。
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;
}
}
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
答案 0 :(得分：2)
instruments数组只有15个成员，因此有效索引为0 - 14。