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/org/apache/xalan/internal/xsltc/ProcessorVersion.java

/*
 * Copyright (c) 2007, 2018, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 2001-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: ProcessorVersion.java,v 1.2.4.1 2005/08/31 10:30:36 pvedula Exp $
 */

package com.sun.org.apache.xalan.internal.xsltc;


/**
 * Admin class that assigns a version number to the XSLTC software.
 * The version number is made up from three fields as in:
 * MAJOR.MINOR[.DELTA]. Fields are incremented based on the following:
 * DELTA field: changes for each bug fix, developer fixing the bug should
 *              increment this field.
 * MINOR field: API changes or a milestone culminating from several
 *              bug fixes. DELTA field goes to zero and MINOR is
 *              incremented such as: {1.0,1.0.1,1.0.2,1.0.3,...1.0.18,1.1}
 * MAJOR field: milestone culminating in fundamental API changes or
 *              architectural changes.  MINOR field goes to zero
 *              and MAJOR is incremented such as: {...,1.1.14,1.2,2.0}
 * Stability of a release follows: X.0 > X.X > X.X.X
 * @author G. Todd Miller
 */
public class ProcessorVersion {
    private static int MAJOR = 1;
    private static int MINOR = 0;
    private static int DELTA = 0;

    public static void main(String[] args) {
        System.out.println("XSLTC version " + MAJOR + "." + MINOR +
            ((DELTA > 0) ? ("."+DELTA) : ("")));
    }
}

⏎ com/sun/org/apache/xalan/internal/xsltc/ProcessorVersion.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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