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/AncestorListener.java

/*
 * Copyright (c) 1997, 1998, 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;

import java.awt.event.*;
import java.awt.*;
import java.util.*;

import javax.swing.*;

/**
 * AncestorListener
 *
 * Interface to support notification when changes occur to a JComponent or one
 * of its ancestors.  These include movement and when the component becomes
 * visible or invisible, either by the setVisible() method or by being added
 * or removed from the component hierarchy.
 *
 * @author Dave Moore
 */
public interface AncestorListener extends EventListener {
    /**
     * Called when the source or one of its ancestors is made visible
     * either by setVisible(true) being called or by its being
     * added to the component hierarchy.  The method is only called
     * if the source has actually become visible.  For this to be true
     * all its parents must be visible and it must be in a hierarchy
     * rooted at a Window
     */
    public void ancestorAdded(AncestorEvent event);

    /**
     * Called when the source or one of its ancestors is made invisible
     * either by setVisible(false) being called or by its being
     * remove from the component hierarchy.  The method is only called
     * if the source has actually become invisible.  For this to be true
     * at least one of its parents must by invisible or it is not in
     * a hierarchy rooted at a Window
     */
    public void ancestorRemoved(AncestorEvent event);

    /**
     * Called when either the source or one of its ancestors is moved.
     */
    public void ancestorMoved(AncestorEvent event);

}

⏎ javax/swing/event/AncestorListener.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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