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Java example source code file (MidiOutDeviceProvider.java)

This example Java source code file (MidiOutDeviceProvider.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

abstractmidideviceprovider, audio, class, midi, mididevice, midioutdeviceinfo, midioutdeviceprovider, sound, string

The MidiOutDeviceProvider.java Java example source code

/*
 * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.media.sound;

import javax.sound.midi.MidiDevice;


/**
 * MIDI output device provider.
 *
 * @author Kara Kytle
 * @author Florian Bomers
 */
public final class MidiOutDeviceProvider extends AbstractMidiDeviceProvider {

    /** Cache of info objects for all MIDI output devices on the system. */
    private static Info[] infos = null;

    /** Cache of open MIDI output devices on the system. */
    private static MidiDevice[] devices = null;

    private final static boolean enabled;

    // STATIC

    static {
        // initialize
        Platform.initialize();
        enabled = Platform.isMidiIOEnabled();
    }

    // CONSTRUCTOR

    /**
     * Required public no-arg constructor.
     */
    public MidiOutDeviceProvider() {
        if (Printer.trace) Printer.trace("MidiOutDeviceProvider: constructor");
    }

    // implementation of abstract methods in AbstractMidiDeviceProvider

    AbstractMidiDeviceProvider.Info createInfo(int index) {
        if (!enabled) {
            return null;
        }
        return new MidiOutDeviceInfo(index, MidiOutDeviceProvider.class);
    }

    MidiDevice createDevice(AbstractMidiDeviceProvider.Info info) {
        if (enabled && (info instanceof MidiOutDeviceInfo)) {
            return new MidiOutDevice(info);
        }
        return null;
    }

    int getNumDevices() {
        if (!enabled) {
            if (Printer.debug)Printer.debug("MidiOutDevice not enabled, returning 0 devices");
            return 0;
        }
        return nGetNumDevices();
    }

    MidiDevice[] getDeviceCache() { return devices; }
    void setDeviceCache(MidiDevice[] devices) { this.devices = devices; }
    Info[] getInfoCache() { return infos; }
    void setInfoCache(Info[] infos) { this.infos = infos; }


    // INNER CLASSES

    /**
     * Info class for MidiOutDevices.  Adds the
     * provider's Class to keep the provider class from being
     * unloaded.  Otherwise, at least on JDK1.1.7 and 1.1.8,
     * the provider class can be unloaded.  Then, then the provider
     * is next invoked, the static block is executed again and a new
     * instance of the device object is created.  Even though the
     * previous instance may still exist and be open / in use / etc.,
     * the new instance will not reflect that state...
     */
    static final class MidiOutDeviceInfo extends AbstractMidiDeviceProvider.Info {
        private final Class providerClass;

        private MidiOutDeviceInfo(int index, Class providerClass) {
            super(nGetName(index), nGetVendor(index), nGetDescription(index), nGetVersion(index), index);
            this.providerClass = providerClass;
        }

    } // class MidiOutDeviceInfo


    // NATIVE METHODS

    private static native int nGetNumDevices();
    private static native String nGetName(int index);
    private static native String nGetVendor(int index);
    private static native String nGetDescription(int index);
    private static native String nGetVersion(int index);
}

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