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/ProcessingInstruction.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;

/**
 * The <code>ProcessingInstruction</code> interface represents a "processing
 * instruction", used in XML as a way to keep processor-specific information
 * in the text of the document.
 * <p> No lexical check is done on the content of a processing instruction and
 * it is therefore possible to have the character sequence
 * <code>"?&gt;"</code> in the content, which is illegal a processing
 * instruction per section 2.6 of [<a href='http://www.w3.org/TR/2004/REC-xml-20040204'>XML 1.0</a>]. The
 * presence of this character sequence must generate a fatal error during
 * serialization.
 * <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>.
 */
public interface ProcessingInstruction extends Node {
    /**
     * The target of this processing instruction. XML defines this as being
     * the first token following the markup that begins the processing
     * instruction.
     */
    public String getTarget();

    /**
     * The content of this processing instruction. This is from the first non
     * white space character after the target to the character immediately
     * preceding the <code>?&gt;</code>.
     */
    public String getData();
    /**
     * The content of this processing instruction. This is from the first non
     * white space character after the target to the character immediately
     * preceding the <code>?&gt;</code>.
     * @exception DOMException
     *   NO_MODIFICATION_ALLOWED_ERR: Raised when the node is readonly.
     */
    public void setData(String data)
                                   throws DOMException;

}

⏎ org/w3c/dom/ProcessingInstruction.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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