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/QueryEval.java

/*
 * Copyright (c) 1999, 2008, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package javax.management;

// java import
import java.io.Serializable;

/**
 * Allows a query to be performed in the context of a specific MBean server.
 *
 * @since 1.5
 */
public abstract class QueryEval implements Serializable {

    /* Serial version */
    private static final long serialVersionUID = 2675899265640874796L;

    private static ThreadLocal<MBeanServer> server =
        new InheritableThreadLocal<MBeanServer>();

    /**
     * <p>Sets the MBean server on which the query is to be performed.
     * The setting is valid for the thread performing the set.
     * It is copied to any threads created by that thread at the moment
     * of their creation.</p>
     *
     * <p>For historical reasons, this method is not static, but its
     * behavior does not depend on the instance on which it is
     * called.</p>
     *
     * @param s The MBean server on which the query is to be performed.
     *
     * @see #getMBeanServer
     */
    public void setMBeanServer(MBeanServer s) {
        server.set(s);
    }

    /**
     * <p>Return the MBean server that was most recently given to the
     * {@link #setMBeanServer setMBeanServer} method by this thread.
     * If this thread never called that method, the result is the
     * value its parent thread would have obtained from
     * <code>getMBeanServer</code> at the moment of the creation of
     * this thread, or null if there is no parent thread.</p>
     *
     * @return the MBean server.
     *
     * @see #setMBeanServer
     *
     */
    public static MBeanServer getMBeanServer() {
        return server.get();
    }
}

⏎ javax/management/QueryEval.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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