JRE 8 rt.jar is the JAR file for JRE 8 RT (Runtime) libraries. JRE (Java Runtime) 8 is the runtime environment included in JDK 8. JRE 8 rt.jar libraries are divided into 6 packages:

com.* - Internal Oracle and Sun Microsystems libraries
java.* - Standard Java API libraries.
javax.* - Extended Java API libraries.
jdk.* -  JDK supporting libraries.
org.* - Third party libraries.
sun.* - Old libraries developed by Sun Microsystems.

JAR File Information:

Directory of C:\fyicenter\jdk-1.8.0_191\jre\lib
      63,596,151 rt.jar

Here is the list of Java classes of the javax.* package in JRE 1.8.0_191 rt.jar. Java source codes are also provided.

⏎ javax/sound/midi/MidiEvent.java

/*
 * Copyright (c) 1999, 2002, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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package javax.sound.midi;

/**
 * MIDI events contain a MIDI message and a corresponding time-stamp
 * expressed in ticks, and can represent the MIDI event information
 * stored in a MIDI file or a <code>{@link Sequence}</code> object.  The
 * duration of a tick is specified by the timing information contained
 * in the MIDI file or <code>Sequence</code> object.
 * <p>
 * In Java Sound, <code>MidiEvent</code> objects are typically contained in a
 * <code>{@link Track}</code>, and <code>Tracks</code> are likewise
 * contained in a <code>Sequence</code>.
 *
 *
 * @author David Rivas
 * @author Kara Kytle
 */
public class MidiEvent {


    // Instance variables

    /**
     * The MIDI message for this event.
     */
    private final MidiMessage message;


    /**
     * The tick value for this event.
     */
    private long tick;


    /**
     * Constructs a new <code>MidiEvent</code>.
     * @param message the MIDI message contained in the event
     * @param tick the time-stamp for the event, in MIDI ticks
     */
    public MidiEvent(MidiMessage message, long tick) {

        this.message = message;
        this.tick = tick;
    }

    /**
     * Obtains the MIDI message contained in the event.
     * @return the MIDI message
     */
    public MidiMessage getMessage() {
        return message;
    }


    /**
     * Sets the time-stamp for the event, in MIDI ticks
     * @param tick the new time-stamp, in MIDI ticks
     */
    public void setTick(long tick) {
        this.tick = tick;
    }


    /**
     * Obtains the time-stamp for the event, in MIDI ticks
     * @return the time-stamp for the event, in MIDI ticks
     */
    public long getTick() {
        return tick;
    }
}

⏎ javax/sound/midi/MidiEvent.java

Or download all of them as a single archive file:

File name: jre-rt-javax-1.8.0_191-src.zip
File size: 5381005 bytes
Release date: 2018-10-28
Download 

⇒ JRE 8 rt.jar - org.* Package Source Code

⇐ JRE 8 rt.jar - java.* Package Source Code

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