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/DOMError.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;

/**
 * <code>DOMError</code> is an interface that describes an error.
 * <p>See also the <a href='http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407'>Document Object Model (DOM) Level 3 Core Specification</a>.
 * @since DOM Level 3
 */
public interface DOMError {
    // ErrorSeverity
    /**
     * The severity of the error described by the <code>DOMError</code> is
     * warning. A <code>SEVERITY_WARNING</code> will not cause the
     * processing to stop, unless <code>DOMErrorHandler.handleError()</code>
     * returns <code>false</code>.
     */
    public static final short SEVERITY_WARNING          = 1;
    /**
     * The severity of the error described by the <code>DOMError</code> is
     * error. A <code>SEVERITY_ERROR</code> may not cause the processing to
     * stop if the error can be recovered, unless
     * <code>DOMErrorHandler.handleError()</code> returns <code>false</code>.
     */
    public static final short SEVERITY_ERROR            = 2;
    /**
     * The severity of the error described by the <code>DOMError</code> is
     * fatal error. A <code>SEVERITY_FATAL_ERROR</code> will cause the
     * normal processing to stop. The return value of
     * <code>DOMErrorHandler.handleError()</code> is ignored unless the
     * implementation chooses to continue, in which case the behavior
     * becomes undefined.
     */
    public static final short SEVERITY_FATAL_ERROR      = 3;

    /**
     * The severity of the error, either <code>SEVERITY_WARNING</code>,
     * <code>SEVERITY_ERROR</code>, or <code>SEVERITY_FATAL_ERROR</code>.
     */
    public short getSeverity();

    /**
     * An implementation specific string describing the error that occurred.
     */
    public String getMessage();

    /**
     *  A <code>DOMString</code> indicating which related data is expected in
     * <code>relatedData</code>. Users should refer to the specification of
     * the error in order to find its <code>DOMString</code> type and
     * <code>relatedData</code> definitions if any.
     * <p ><b>Note:</b>  As an example,
     * <code>Document.normalizeDocument()</code> does generate warnings when
     * the "split-cdata-sections" parameter is in use. Therefore, the method
     * generates a <code>SEVERITY_WARNING</code> with <code>type</code>
     * <code>"cdata-sections-splitted"</code> and the first
     * <code>CDATASection</code> node in document order resulting from the
     * split is returned by the <code>relatedData</code> attribute.
     */
    public String getType();

    /**
     * The related platform dependent exception if any.
     */
    public Object getRelatedException();

    /**
     *  The related <code>DOMError.type</code> dependent data if any.
     */
    public Object getRelatedData();

    /**
     * The location of the error.
     */
    public DOMLocator getLocation();

}

⏎ org/w3c/dom/DOMError.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

⇑ Download and Use JDK 8

⇑⇑ FAQ for JDK (Java Development Kit)