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/InvalidNameException.java

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

package javax.naming;

/**
  * This exception indicates that the name being specified does
  * not conform to the naming syntax of a naming system.
  * This exception is thrown by any of the methods that does name
  * parsing (such as those in Context, DirContext, CompositeName and CompoundName).
  * <p>
  * Synchronization and serialization issues that apply to NamingException
  * apply directly here.
  *
  * @author Rosanna Lee
  * @author Scott Seligman
  *
  * @see Context
  * @see javax.naming.directory.DirContext
  * @see CompositeName
  * @see CompoundName
  * @see NameParser
  * @since 1.3
  */

public class InvalidNameException extends NamingException {
    /**
      * Constructs an instance of InvalidNameException using an
      * explanation of the problem.
      * All other fields are initialized to null.
      * @param explanation      A possibly null message explaining the problem.
      * @see java.lang.Throwable#getMessage
      */
    public InvalidNameException(String explanation) {
        super(explanation);
    }

    /**
      * Constructs an instance of InvalidNameException with
      * all fields set to null.
      */
    public InvalidNameException() {
        super();
    }

    /**
     * Use serialVersionUID from JNDI 1.1.1 for interoperability
     */
    private static final long serialVersionUID = -8370672380823801105L;
}

⏎ javax/naming/InvalidNameException.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

⇑ Download and Use JDK 8

⇑⇑ FAQ for JDK (Java Development Kit)