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

⏎ com/sun/javadoc/PackageDoc.java

/*
 * Copyright (c) 1998, 2006, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
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 *
 *
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 */

package com.sun.javadoc;

/**
 * Represents a java package.  Provides access to information
 * about the package, the package's comment and tags, and the
 * classes in the package.
 * <p>
 * Each method whose return type is an array will return an empty
 * array (never null) when there are no objects in the result.
 *
 * @since 1.2
 * @author Kaiyang Liu (original)
 * @author Robert Field (rewrite)
 */
public interface PackageDoc extends Doc {

    /**
     * Get all classes and interfaces in the package, filtered to the specified
     * <a href="{@docRoot}/com/sun/javadoc/package-summary.html#included">access
     * modifier option</a>.
     *
     * @return       filtered classes and interfaces in this package
     * @param filter Specifying true filters according to the specified access
     *               modifier option.
     *               Specifying false includes all classes and interfaces
     *               regardless of access modifier option.
     * @since 1.4
     */
    ClassDoc[] allClasses(boolean filter);

    /**
     * Get all
     * <a href="{@docRoot}/com/sun/javadoc/package-summary.html#included">included</a>
     * classes and interfaces in the package.  Same as allClasses(true).
     *
     * @return all included classes and interfaces in this package.
     */
    ClassDoc[] allClasses();

    /**
     * Get included
     * <a href="{@docRoot}/com/sun/javadoc/package-summary.html#class">ordinary</a>
     * classes (that is, exclude exceptions, errors, enums, interfaces, and
     * annotation types)
     * in this package.
     *
     * @return included ordinary classes in this package.
     */
    ClassDoc[] ordinaryClasses();

    /**
     * Get included Exception classes in this package.
     *
     * @return included Exceptions in this package.
     */
    ClassDoc[] exceptions();

    /**
     * Get included Error classes in this package.
     *
     * @return included Errors in this package.
     */
    ClassDoc[] errors();

    /**
     * Get included enum types in this package.
     *
     * @return included enum types in this package.
     * @since 1.5
     */
    ClassDoc[] enums();

    /**
     * Get included interfaces in this package, omitting annotation types.
     *
     * @return included interfaces in this package.
     */
    ClassDoc[] interfaces();

    /**
     * Get included annotation types in this package.
     *
     * @return included annotation types in this package.
     * @since 1.5
     */
    AnnotationTypeDoc[] annotationTypes();

    /**
     * Get the annotations of this package.
     * Return an empty array if there are none.
     *
     * @return the annotations of this package.
     * @since 1.5
     */
    AnnotationDesc[] annotations();

    /**
     * Lookup a class or interface within this package.
     *
     * @return ClassDoc of found class or interface,
     * or null if not found.
     */
    ClassDoc findClass(String className);
}

⏎ com/sun/javadoc/PackageDoc.java

Or download all of them as a single archive file:

File name: jre-rt-com-1.8.0_191-src.zip
File size: 8099783 bytes
Release date: 2018-10-28
Download 

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