I've copied the code from chapter 13 of the book Head First Java, page 420 to study and play around with, but the code doesn't seem to work as advertised.
First of all, the beat does not start at the first input on the GUI. If I place a cymbal splash on beat one to kick off the beat, and a snare on beat 3, the program plays back: Snare - splash.
Secondly, most sounds are not there, instead playing hihat or snare sounds. The Whistle, cowbell and maracass sounds play back hi hats.
Is there something that has changed in Java since this book was released, or are there bugs in the code written in the book. How do I change this code to play correctly and with the right sounds?
Thanks
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", "Open Hi-Hat","Acoustic Snare",
"Crash Cymbal", "Hand Clap", "High Tom", "Hi Bongo", "Maracas", "Whistle", "Low Conga", "Cowbell",
"Vibraslap", "Low-mid Tom", "High Agogo", "Open Hi Conga" };
int[]instruments={35,42,46,38,49,39,50,60,70,72,64,56,58,47,67,63};
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<JCheckBox>();
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);
} // end loop
setUpMidi();
theFrame.setBounds(50,50,300,300);
theFrame.pack();
theFrame.setVisible(true);
} // close method
public void setUpMidi(){
try{
sequencer=MidiSystem.getSequencer();
sequencer.open();
sequence=new Sequence(Sequence.PPQ,4);
track=sequence.createTrack();
sequencer.setTempoInBPM(120);
}catch(Exception e){ e.printStackTrace(); }
} // close method
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;
}
} // close inner loop
makeTracks(trackList);
track.add(makeEvent(176,1,127,0,16));
} // close outer
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 buildTrackAndStart method
public class MyStartListener implements ActionListener{
public void actionPerformed(ActionEvent a){
buildTrackAndStart();
}
} // close inner class
public class MyStopListener implements ActionListener{
public void actionPerformed(ActionEvent a){
sequencer.stop();}
} // close inner class
public class MyUpTempoListener implements ActionListener{
public void actionPerformed(ActionEvent a){
float tempoFactor=sequencer.getTempoFactor();
sequencer.setTempoFactor((float)(tempoFactor*1.03));
}
} // close inner class
public class MyDownTempoListener implements ActionListener{
public void actionPerformed(ActionEvent a){
float tempoFactor=sequencer.getTempoFactor();
sequencer.setTempoFactor((float)(tempoFactor*.97));
}
} // close inner class
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){
e.printStackTrace();}
return event;
}
} // close class
