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/omg/CORBA/ULongLongSeqHolder.java

/*
 * Copyright (c) 1999, 2001, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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package org.omg.CORBA;


/**
* The Holder for <tt>ULongLongSeq</tt>.  For more information on
* Holder files, see <a href="doc-files/generatedfiles.html#holder">
* "Generated Files: Holder Files"</a>.<P>
* org/omg/CORBA/ULongLongSeqHolder.java
* Generated by the IDL-to-Java compiler (portable), version "3.0"
* from streams.idl
* 13 May 1999 22:41:37 o'clock GMT+00:00
*/

public final class ULongLongSeqHolder implements org.omg.CORBA.portable.Streamable
{
    public long value[] = null;

    public ULongLongSeqHolder ()
    {
    }

    public ULongLongSeqHolder (long[] initialValue)
    {
        value = initialValue;
    }

    public void _read (org.omg.CORBA.portable.InputStream i)
    {
        value = org.omg.CORBA.ULongLongSeqHelper.read (i);
    }

    public void _write (org.omg.CORBA.portable.OutputStream o)
    {
        org.omg.CORBA.ULongLongSeqHelper.write (o, value);
    }

    public org.omg.CORBA.TypeCode _type ()
    {
        return org.omg.CORBA.ULongLongSeqHelper.type ();
    }

}

⏎ org/omg/CORBA/ULongLongSeqHolder.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)