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 org.* package in JRE 1.8.0_191 rt.jar. Java source codes are also provided.

⏎ org/w3c/dom/ls/LSException.java

/*
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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/*
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 * Copyright (c) 2004 World Wide Web Consortium,
 *
 * (Massachusetts Institute of Technology, European Research Consortium for
 * Informatics and Mathematics, Keio University). All Rights Reserved. This
 * work is distributed under the W3C(r) Software License [1] in the hope that
 * it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
 */

package org.w3c.dom.ls;

/**
 *  Parser or write operations may throw an <code>LSException</code> if the
 * processing is stopped. The processing can be stopped due to a
 * <code>DOMError</code> with a severity of
 * <code>DOMError.SEVERITY_FATAL_ERROR</code> or a non recovered
 * <code>DOMError.SEVERITY_ERROR</code>, or if
 * <code>DOMErrorHandler.handleError()</code> returned <code>false</code>.
 * <p ><b>Note:</b>  As suggested in the definition of the constants in the
 * <code>DOMError</code> interface, a DOM implementation may choose to
 * continue after a fatal error, but the resulting DOM tree is then
 * implementation dependent.
 * <p>See also the <a href='http://www.w3.org/TR/2004/REC-DOM-Level-3-LS-20040407'>Document Object Model (DOM) Level 3 Load
and Save Specification</a>.
 */
public class LSException extends RuntimeException {
    public LSException(short code, String message) {
       super(message);
       this.code = code;
    }
    public short   code;
    // LSExceptionCode
    /**
     *  If an attempt was made to load a document, or an XML Fragment, using
     * <code>LSParser</code> and the processing has been stopped.
     */
    public static final short PARSE_ERR                 = 81;
    /**
     *  If an attempt was made to serialize a <code>Node</code> using
     * <code>LSSerializer</code> and the processing has been stopped.
     */
    public static final short SERIALIZE_ERR             = 82;

}

⏎ org/w3c/dom/ls/LSException.java

Or download all of them as a single archive file:

File name: jre-rt-org-1.8.0_191-src.zip
File size: 951125 bytes
Release date: 2018-10-28
Download 

⇒ JRE 8 rt.jar - com.* Package Source Code

⇐ JRE 8 rt.jar - javax.* Package Source Code

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⇑⇑ FAQ for JDK (Java Development Kit)