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/print/ServiceUIFactory.java

/*
 * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

package javax.print;

/**
 * Services may optionally provide UIs which allow different styles
 * of interaction in different roles.
 * One role may be end-user browsing and setting of print options.
 * Another role may be administering the print service.
 * <p>
 * Although the Print Service API does not presently provide standardised
 * support for administering a print service, monitoring of the print
 * service is possible and a UI may provide for private update mechanisms.
 * <p>
 * The basic design intent is to allow applications to lazily locate and
 * initialize services only when needed without any API dependencies
 * except in an environment in which they are used.
 * <p>
 * Swing UIs are preferred as they provide a more consistent {@literal L&F}
 * and can support accessibility APIs.
 * <p>
 * Example usage:
 * <pre>
 *  ServiceUIFactory factory = printService.getServiceUIFactory();
 *  if (factory != null) {
 *      JComponent swingui = (JComponent)factory.getUI(
 *                                         ServiceUIFactory.MAIN_UIROLE,
 *                                         ServiceUIFactory.JCOMPONENT_UI);
 *      if (swingui != null) {
 *          tabbedpane.add("Custom UI", swingui);
 *      }
 *  }
 * </pre>
 */

public abstract class ServiceUIFactory {

    /**
     * Denotes a UI implemented as a Swing component.
     * The value of the String is the fully qualified classname :
     * "javax.swing.JComponent".
     */
    public static final String JCOMPONENT_UI = "javax.swing.JComponent";

    /**
     * Denotes a UI implemented as an AWT panel.
     * The value of the String is the fully qualified classname :
     * "java.awt.Panel"
     */
    public static final String PANEL_UI = "java.awt.Panel";

    /**
     * Denotes a UI implemented as an AWT dialog.
     * The value of the String is the fully qualified classname :
     * "java.awt.Dialog"
     */
    public static final String DIALOG_UI = "java.awt.Dialog";

    /**
     * Denotes a UI implemented as a Swing dialog.
     * The value of the String is the fully qualified classname :
     * "javax.swing.JDialog"
     */
    public static final String JDIALOG_UI = "javax.swing.JDialog";

    /**
     * Denotes a UI which performs an informative "About" role.
     */
    public static final int ABOUT_UIROLE = 1;

    /**
     * Denotes a UI which performs an administrative role.
     */
    public static final int ADMIN_UIROLE = 2;

    /**
     * Denotes a UI which performs the normal end user role.
     */
    public static final int MAIN_UIROLE = 3;

    /**
     * Not a valid role but role id's greater than this may be used
     * for private roles supported by a service. Knowledge of the
     * function performed by this role is required to make proper use
     * of it.
     */
    public static final int RESERVED_UIROLE = 99;
    /**
     * Get a UI object which may be cast to the requested UI type
     * by the application and used in its user interface.
     * <P>
     * @param role requested. Must be one of the standard roles or
     * a private role supported by this factory.
     * @param ui type in which the role is requested.
     * @return the UI role or null if the requested UI role is not available
     * from this factory
     * @throws IllegalArgumentException if the role or ui is neither
     * one of the standard ones, nor a private one
     * supported by the factory.
     */
    public abstract Object getUI(int role, String ui) ;

    /**
     * Given a UI role obtained from this factory obtain the UI
     * types available from this factory which implement this role.
     * The returned Strings should refer to the static variables defined
     * in this class so that applications can use equality of reference
     * ("==").
     * @param role to be looked up.
     * @return the UI types supported by this class for the specified role,
     * null if no UIs are available for the role.
     * @throws IllegalArgumentException is the role is a non-standard
     * role not supported by this factory.
     */
    public abstract String[] getUIClassNamesForRole(int role) ;



}

⏎ javax/print/ServiceUIFactory.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)