Head First Java problem

[Pete Blamire]

Hi all,

Wondered if anyone had ever come across this problem...

I'm working my way through the Head First Java book, and am putting together the music player. Reached the third part of that, combining blobs and music. what I've found is that I get no sound (yep I have checked the volume . Also I only get a window and no blobs. When I use the downloaded code I get the blobs but still no music. I'm puzzled as I can't see any obvious typos in my code, included below in case you guys can.

Cheers,
Pete.

import javax.sound.midi.*;
import java.io.*;
import javax.swing.*;
import java.awt.*;

public class MiniMusicPlayer3 {
	
	static JFrame f = new JFrame("My first music video");
	static MyDrawPanel ml;
	
	public static void main(String[] args) {
		MiniMusicPlayer3 mmp = new MiniMusicPlayer3();
		mmp.go();
	}
	
	public void setUpGUI() {
		ml = new MyDrawPanel();
		f.setContentPane(ml);
		f.setBounds(30, 30, 300, 300);
		f.setVisible(true);
	}
	
	public void go() {
		setUpGUI();
		
		try {
			
			Sequencer sequencer = MidiSystem.getSequencer();
			sequencer.open();
			sequencer.addControllerEventListener(ml, new int[] {127});
			Sequence seq = new Sequence(Sequence.PPQ, 4);
			Track track = seq.createTrack();
			
			int r = 0;
			for (int i = 0; i < 60; i += 4 ) {
				r = (int) ((Math.random() * 50) + 1);
				track.add(makeEvent(144,1,r,100,i));
				track.add(makeEvent(176,1,127,0,i));
				track.add(makeEvent(128,1,r,100,i+2));
			}
			
			sequencer.setSequence(seq);
			sequencer.start();
			sequencer.setTempoInBPM(120);
		} catch (Exception ex) { ex.printStackTrace();}
	}
	
	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;
	}
	
	class MyDrawPanel extends JPanel implements ControllerEventListener {
		boolean msg = false;
		
		public void controlChange(ShortMessage event) {
			msg = true;
			repaint();
		}
		
		public void paintComponent(Graphics2D g) {
			if (msg) {
				Graphics2D g2 = (Graphics2D) g;
				int r = (int) (Math.random() * 250);
				int gr = (int) (Math.random() * 250);
				int b = (int) (Math.random() * 250);
				
				g.setColor(new Color(r,gr,b));
				
				int ht = (int) ((Math.random() * 120) + 10);
				int width = (int) ((Math.random() * 120) + 10);
				int x = (int) ((Math.random() * 40) + 10);
				int y = (int) ((Math.random() * 40) + 10);
				
				g.fillRect(x, y, ht, width);
				msg = false;
			}
		}
	}
	
}

[Ulf Dittmer]

This is a bad idea:

} catch (Exception e) { }

How will you know if there are problems? At least print something to the console.

[Campbell Ritchie]

. . . and welcome to JavaRanch

[sujani Koya]

I compiled this same text and ran it. I was getting the music but a blank frame.

I wrote a program for this on my own with frequent updates from the book - without copying directly- and i get music with a single rectange that does not change with the note.

Some technical guru ought to guide us to find the problem. Anyone??

sujani

[Ogeh Ikem]

Try overriding the paintComponent method by changing

public void paintComponent(Graphics2D g) 

to

@Override
public void paintComponent(Graphics g) 

[Matt Hanrahan]

I'm guessing this is all old news, but you may want to try to change the paintComponent lines to:

public void paintComponent (Graphics g) {
		
		 Graphics2D g2d = (Graphics2D) g;

I just compiled and ran a slightly different version and it all seems to work fine. If you'd like to try it I will post it below.
Did the first two iterations work on the command line? I'm just learning also, but hopefully this will help.
I added a little code to the catch statements also.

I was also having the closing problem as discussed in some other forum topics, and so add an EXIT_ON_CLOSE statement to the setUpGui method.

Good Luck,
Matt

import javax.sound.midi.*;
import javax.swing.*;
import java.awt.*;
import java.io.*;

public class MiniMusicPlayer3 {
	
	static JFrame f = new JFrame ("My First Music Video");
	static MyDrawPanel ml;
	
	public static void main (String [] args) {
		MiniMusicPlayer3 mini = new MiniMusicPlayer3 ();
		mini.go();
	}
	
	public void setUpGui () {
		ml = new MyDrawPanel ();
		f.setContentPane(ml);
		f.setBounds (30,30, 300,300);
		f.setVisible(true);
		f.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
	}
	
	public void go () {
		
		setUpGui();
		
		try {
			Sequencer sequencer = MidiSystem.getSequencer ();
			sequencer.open ();
			sequencer.addControllerEventListener (ml, new int[] {127});
			Sequence seq = new Sequence(Sequence.PPQ, 4);
			Track track = seq.createTrack();
			
			int r = 0;
			for (int i = 0; i < 60; i += 4) {
				
				r = (int) ((Math.random() * 50) + 1);
				track.add(makeEvent (144,1,r,100,i));
				track.add(makeEvent(176,1,127,0,i));
				track.add(makeEvent(128,1,r,100,i+2));
			}
		
			sequencer.setSequence(seq);
			sequencer.setTempoInBPM(220);
			sequencer.start();
		} catch (Exception ex) {
			System.out.println ("add track create sequence failed");
			ex.printStackTrace();
		}
	}	
	
		public static 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) {
			System.out.print ("make midi event failed");
			e.printStackTrace();
		}
		return event;
	}
	
	class MyDrawPanel extends JPanel implements ControllerEventListener {
		boolean msg = false;
		
		public void controlChange (ShortMessage event) {
			msg = true;
			repaint();
		}
		
		public void paintComponent (Graphics g) {
			if (msg) {
				
				int r = (int) (Math.random() * 250);
				int gr = (int) (Math.random() * 250);
				int b = (int) (Math.random() * 250);
				
				g.setColor (new Color (r,gr,b));
				
				int ht = (int) ((Math.random() * 120) + 10);
				int width = (int) ((Math.random() * 120) + 10);
				
				int x = (int) ((Math.random() * 40) + 10);
				int y = (int) ((Math.random() * 40) + 10);
				
				g.fillRect(x,y,ht, width);
				msg = false;
			}
		}
	}
}