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

⏎ javax/naming/Referenceable.java

/*
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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package javax.naming;

/**
  * This interface is implemented by an object that can provide a
  * Reference to itself.
  *<p>
  * A Reference represents a way of recording address information about
  * objects which themselves are not directly bound to the naming system.
  * Such objects can implement the Referenceable interface as a way
  * for programs that use that object to determine what its Reference is.
  * For example, when binding a object, if an object implements the
  * Referenceable interface, getReference() can be invoked on the object to
  * get its Reference to use for binding.
  *
  * @author Rosanna Lee
  * @author Scott Seligman
  * @author R. Vasudevan
  *
  * @see Context#bind
  * @see javax.naming.spi.NamingManager#getObjectInstance
  * @see Reference
  * @since 1.3
  */
public interface Referenceable {
    /**
      * Retrieves the Reference of this object.
      *
      * @return The non-null Reference of this object.
      * @exception NamingException If a naming exception was encountered
      *         while retrieving the reference.
      */
    Reference getReference() throws NamingException;
}

⏎ javax/naming/Referenceable.java

Or download all of them as a single archive file:

File name: jre-rt-javax-1.8.0_191-src.zip
File size: 5381005 bytes
Release date: 2018-10-28
Download 

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

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

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