Ok so I'm learning from the book Head First Java, second edition, and I'm having a little trouble with some code. The code I'm working with compiles just fine and gives the output that I want(sort of) but whenever I run the code is doesn't stop, as if it was in an endless loop even though I don't have a single loop in my code. Ok so here is my code:

import javax.sound.midi.*;
public class MusicPlayer2 {
    public static void main(String[] args){
        MusicPlayer2 MusicPlayer = new MusicPlayer2();
        if(args.length < 2){
            System.out.println("Instrument and Note arguments");
        } else {
            int instrument = Integer.parseInt(args[0]);
            int note = Integer.parseInt(args[1]);
            MusicPlayer.play(instrument, note);
    public void play(int instrument, int note){
            Sequencer Player = MidiSystem.getSequencer();
            Sequence seq = new Sequence(Sequence.PPQ, 4);
            Track track = seq.createTrack();

            MidiEvent event = null;

            ShortMessage first = new ShortMessage();
            first.setMessage(192, 1, instrument, 0);
            MidiEvent ChangeInstrument = new MidiEvent(first, 1);

            ShortMessage a = new ShortMessage();
            a.setMessage(144, 1, note, 100);
            MidiEvent noteOn = new MidiEvent(a, 1);

            ShortMessage b = new ShortMessage();
            b.setMessage(128, 1, note, 100);
            MidiEvent noteOff = new MidiEvent(a, 16);
        } catch(Exception ex){ex.printStackTrace();}

This code is meant to be run from the command line like this:

java MusicPlayer2 8 90 //The two numbers can be anything from 0 to 127

I wrote another version of this so that it has default values and when I run the code I get the sound, then it just keeps running as if it was in a loop but nothing is going on. Thanks in advance.

I really need help with this if someone could help me it would be awesome!