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/colorchooser/ColorChooserComponentFactory.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.colorchooser;

import javax.swing.JComponent;

/**
 * A class designed to produce preconfigured "accessory" objects to
 * insert into color choosers.
 *
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases. The current serialization support is
 * appropriate for short term storage or RMI between applications running
 * the same version of Swing.  As of 1.4, support for long term storage
 * of all JavaBeans&trade;
 * has been added to the <code>java.beans</code> package.
 * Please see {@link java.beans.XMLEncoder}.
 *
 * @author Steve Wilson
 */
public class ColorChooserComponentFactory {

    private ColorChooserComponentFactory() { } // can't instantiate

    public static AbstractColorChooserPanel[] getDefaultChooserPanels() {
        return new AbstractColorChooserPanel[] {
                new DefaultSwatchChooserPanel(),
                new ColorChooserPanel(new ColorModelHSV()),
                new ColorChooserPanel(new ColorModelHSL()),
                new ColorChooserPanel(new ColorModel()),
                new ColorChooserPanel(new ColorModelCMYK()),
        };
    }

    public static JComponent getPreviewPanel() {
        return new DefaultPreviewPanel();
    }
}

⏎ javax/swing/colorchooser/ColorChooserComponentFactory.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

⇑ Download and Use JDK 8

⇑⇑ FAQ for JDK (Java Development Kit)