Java compilation error

Question

Java

There is a program code, an example from the book. It has one large class, which has internal ones. When compiling, it swears at the same thing: "is not abstract and does not override abstract method".
Here is the actual code:

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 Share", "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");
        start.addActionListener (new MyUpTempoListener());
        buttonBox.add(upTempo);
        JButton downTempo = new JButton ("Tempo Down");
        start.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);
  }
  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();}
  }
  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();}
}
  
private class MyStartListener implements ActionListener {
    public void actionPerfomed(ActionEvent a) {
      buildTrackAndStart();
    }
}
private class MyStopListener implements ActionListener {
   public void actionPerfomed (ActionEvent a) {
     sequencer.stop();
   }
 }
public class MyUpTempoListener implements ActionListener {
   public void actionPerfomed(ActionEvent a) {
      float tempoFactor = sequencer.getTempoFactor();
        sequencer.setTempoFactor((float) (tempoFactor * 1.03));
    }
 }
public class MyDownTempoListener implements ActionListener {
   public void actionPerfomed(ActionEvent a) {
     float tempoFactor = sequencer.getTempoFactor();
        sequencer.setTempoFactor((float) (tempoFactor * .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(144,9,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;
   }
 }

When googling, it turned out that in early versions Java did not swear at this, but I did not find a sensible solution.

Answer 1

You have a typo in your actionPerfo r med method.