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/CosNaming/NamingContextPackage/NotFoundReason.java

package org.omg.CosNaming.NamingContextPackage;


/**
* org/omg/CosNaming/NamingContextPackage/NotFoundReason.java .
* Generated by the IDL-to-Java compiler (portable), version "3.2"
* from c:/re/workspace/8-2-build-windows-amd64-cygwin/jdk8u191/11896/corba/src/share/classes/org/omg/CosNaming/nameservice.idl
* Saturday, October 6, 2018 9:30:40 AM PDT
*/


/**
         * Indicates the reason for not able to resolve.
         */
public class NotFoundReason implements org.omg.CORBA.portable.IDLEntity
{
  private        int __value;
  private static int __size = 3;
  private static org.omg.CosNaming.NamingContextPackage.NotFoundReason[] __array = new org.omg.CosNaming.NamingContextPackage.NotFoundReason [__size];

  public static final int _missing_node = 0;
  public static final org.omg.CosNaming.NamingContextPackage.NotFoundReason missing_node = new org.omg.CosNaming.NamingContextPackage.NotFoundReason(_missing_node);
  public static final int _not_context = 1;
  public static final org.omg.CosNaming.NamingContextPackage.NotFoundReason not_context = new org.omg.CosNaming.NamingContextPackage.NotFoundReason(_not_context);
  public static final int _not_object = 2;
  public static final org.omg.CosNaming.NamingContextPackage.NotFoundReason not_object = new org.omg.CosNaming.NamingContextPackage.NotFoundReason(_not_object);

  public int value ()
  {
    return __value;
  }

  public static org.omg.CosNaming.NamingContextPackage.NotFoundReason from_int (int value)
  {
    if (value >= 0 && value < __size)
      return __array[value];
    else
      throw new org.omg.CORBA.BAD_PARAM ();
  }

  protected NotFoundReason (int value)
  {
    __value = value;
    __array[__value] = this;
  }
} // class NotFoundReason

⏎ org/omg/CosNaming/NamingContextPackage/NotFoundReason.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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