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/URIException.java

/*
 * Copyright (c) 2000, 2001, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package javax.print;

import java.net.URI;

/**
 * Interface URIException is a mixin interface which a subclass of {@link
 * PrintException PrintException} can implement to report an error condition
 * involving a URI address. The Print Service API does not define any print
 * exception classes that implement interface URIException, that being left to
 * the Print Service implementor's discretion.
 *
 */

public interface URIException {

    /**
     * Indicates that the printer cannot access the URI address.
     * For example, the printer might report this error if it goes to get
     * the print data and cannot even establish a connection to the
     * URI address.
     */
    public static final int URIInaccessible = 1;

    /**
     * Indicates that the printer does not support the URI
     * scheme ("http", "ftp", etc.) in the URI address.
     */
    public static final int URISchemeNotSupported = 2;

    /**
     * Indicates any kind of problem not specifically identified
     * by the other reasons.
     */
    public static final int URIOtherProblem = -1;

    /**
     * Return the URI.
     * @return the URI that is the cause of this exception.
     */
    public URI getUnsupportedURI();

    /**
     * Return the reason for the event.
     * @return one of the predefined reasons enumerated in this interface.
     */
    public int getReason();

}

⏎ javax/print/URIException.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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