Program the MIDI percussion channel with a Swing window : MIDI « Development Class « Java

Program the MIDI percussion channel with a Swing window

 * Copyright (c) 2004 David Flanagan.  All rights reserved.
 * This code is from the book Java Examples in a Nutshell, 3nd Edition.
 * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
 * You may study, use, and modify it for any non-commercial purpose,
 * including teaching and use in open-source projects.
 * You may distribute it non-commercially as long as you retain this notice.
 * For a commercial use license, or to purchase the book, 
 * please visit

import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;

import javax.sound.midi.MidiChannel;
import javax.sound.midi.MidiSystem;
import javax.sound.midi.MidiUnavailableException;
import javax.sound.midi.Synthesizer;
import javax.swing.JFrame;

 * This program the MIDI percussion channel with a Swing window. It monitors
 * keystrokes and mouse motion in the window and uses them to create music.
 * Keycodes between 35 and 81, inclusive, generate different percussive sounds.
 * See the VK_ constants in java.awt.event.KeyEvent, or just experiment. Mouse
 * position controls volume: move the mouse to the right of the window to
 * increase the volume.
public class Drums extends JFrame {
  MidiChannel channel; // The channel we play on: 10 is for percussion

  int velocity = 64; // Default volume is 50%

  public static void main(String[] args) throws MidiUnavailableException {
    // We don't need a Sequencer in this example, since we send MIDI
    // events directly to the Synthesizer instead.
    Synthesizer synthesizer = MidiSystem.getSynthesizer();;
    JFrame frame = new Drums(synthesizer);

    frame.setSize(50, 128); // We use window width as volume control

  public Drums(Synthesizer synth) {

    // Channel 10 is the GeneralMidi percussion channel. In Java code, we
    // number channels from 0 and use channel 9 instead.
    channel = synth.getChannels()[9];

    addKeyListener(new KeyAdapter() {
      public void keyPressed(KeyEvent e) {
        int key = e.getKeyCode();
        if (key >= 35 && key <= 81) {
          channel.noteOn(key, velocity);

      public void keyReleased(KeyEvent e) {
        int key = e.getKeyCode();
        if (key >= 35 && key <= 81)

    addMouseMotionListener(new MouseMotionAdapter() {
      public void mouseMoved(MouseEvent e) {
        velocity = e.getX();


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