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/swing/event/InternalFrameAdapter.java

/*
 * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package javax.swing.event;

/**
 * An abstract adapter class for receiving internal frame events.
 * The methods in this class are empty. This class exists as
 * convenience for creating listener objects, and is functionally
 * equivalent to the WindowAdapter class in the AWT.
 * <p>
 * See <a href="https://docs.oracle.com/javase/tutorial/uiswing/events/internalframelistener.html">How to Write an Internal Frame Listener</a>
 * in <em>The Java Tutorial</em>
 *
 * @see InternalFrameEvent
 * @see InternalFrameListener
 * @see java.awt.event.WindowListener
 *
 * @author Thomas Ball
 */
public abstract class InternalFrameAdapter implements InternalFrameListener {
    /**
     * Invoked when an internal frame has been opened.
     */
    public void internalFrameOpened(InternalFrameEvent e) {}

    /**
     * Invoked when an internal frame is in the process of being closed.
     * The close operation can be overridden at this point.
     */
    public void internalFrameClosing(InternalFrameEvent e) {}

    /**
     * Invoked when an internal frame has been closed.
     */
    public void internalFrameClosed(InternalFrameEvent e) {}

    /**
     * Invoked when an internal frame is iconified.
     */
    public void internalFrameIconified(InternalFrameEvent e) {}

    /**
     * Invoked when an internal frame is de-iconified.
     */
    public void internalFrameDeiconified(InternalFrameEvent e) {}

    /**
     * Invoked when an internal frame is activated.
     */
    public void internalFrameActivated(InternalFrameEvent e) {}

    /**
     * Invoked when an internal frame is de-activated.
     */
    public void internalFrameDeactivated(InternalFrameEvent e) {}
}

⏎ javax/swing/event/InternalFrameAdapter.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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