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/management/remote/JMXAddressable.java

/*
 * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package javax.management.remote;

/**
 * <p>Implemented by objects that can have a {@code JMXServiceURL} address.
 * All {@link JMXConnectorServer} objects implement this interface.
 * Depending on the connector implementation, a {@link JMXConnector}
 * object may implement this interface too.  {@code JMXConnector}
 * objects for the RMI Connector are instances of
 * {@link javax.management.remote.rmi.RMIConnector RMIConnector} which
 * implements this interface.</p>
 *
 * <p>An object implementing this interface might not have an address
 * at a given moment.  This is indicated by a null return value from
 * {@link #getAddress()}.</p>
 *
 * @since 1.6
 */
public interface JMXAddressable {
    /**
     * <p>The address of this object.</p>
     *
     * @return the address of this object, or null if it
     * does not have one.
     */
    public JMXServiceURL getAddress();
}

⏎ javax/management/remote/JMXAddressable.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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