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/cmdline/getopt/GetOpt.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: GetOpt.java,v 1.2.4.1 2005/08/31 11:46:04 pvedula Exp $
 */

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

import java.util.ArrayList;
import java.util.List;
import java.util.ListIterator;

import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ErrorMsg;


/**
* GetOpt is a Java equivalent to the C getopt() library function
* discussed in man page getopt(3C). It provides command line
* parsing for Java applications. It supports the most rules of the
* command line standard (see man page intro(1)) including stacked
* options such as '-sxm' (which is equivalent to -s -x -m); it
* handles special '--' option that signifies the end of options.
* Additionally this implementation of getopt will check for
* mandatory arguments to options such as in the case of
* '-d <file>' it will throw a MissingOptArgException if the
* option argument '<file>' is not included on the commandline.
* getopt(3C) does not check for this.
 * @author G Todd Miller
*/
public class GetOpt{
    public GetOpt(String[] args, String optString){
        theOptions = new ArrayList();
        int currOptIndex = 0;
        theCmdArgs = new ArrayList();
        theOptionMatcher = new OptionMatcher(optString);
        // fill in the options list
        for(int i=0; i<args.length; i++){
            String token = args[i];
            int tokenLength = token.length();
            if(token.equals("--")){         // end of opts
                currOptIndex = i+1;         // set index of first operand
                break;                      // end of options
            }
            else if(token.startsWith("-") && tokenLength == 2){
                // simple option token such as '-s' found
                theOptions.add(new Option(token.charAt(1)));
            }
            else if(token.startsWith("-") && tokenLength > 2){
                // stacked options found, such as '-shm'
                // iterate thru the tokens after the dash and
                // add them to theOptions list
                for(int j=1; j<tokenLength; j++){
                    theOptions.add(new Option(token.charAt(j)));
                }
            }
            else if(!token.startsWith("-")){
                // case 1- there are not options stored yet therefore
                // this must be an command argument, not an option argument
                if(theOptions.size() == 0){
                    currOptIndex = i;
                    break;              // stop processing options
                }
                else {
                    // case 2-
                    // there are options stored, check to see if
                    // this arg belong to the last arg stored
                    int indexoflast=0;
                    indexoflast = theOptions.size()-1;
                    Option op = (Option)theOptions.get(indexoflast);
                    char opLetter = op.getArgLetter();
                    if(!op.hasArg() && theOptionMatcher.hasArg(opLetter)){
                        op.setArg(token);
                    }
                    else{
                        // case 3 -
                        // the last option stored does not take
                        // an argument, so again, this argument
                        // must be a command argument, not
                        // an option argument
                        currOptIndex = i;
                        break;                  // end of options
                    }
                }
            }// end option does not start with "-"
        } // end for args loop

        //  attach an iterator to list of options
        theOptionsIterator = theOptions.listIterator();

        // options are done, now fill out cmd arg list with remaining args
        for(int i=currOptIndex; i<args.length; i++){
            String token = args[i];
            theCmdArgs.add(token);
        }
    }


    /**
    * debugging routine to print out all options collected
    */
    public void printOptions(){
        for(ListIterator it=theOptions.listIterator(); it.hasNext();){
            Option opt = (Option)it.next();
            System.out.print("OPT =" + opt.getArgLetter());
            String arg = opt.getArgument();
            if(arg != null){
               System.out.print(" " + arg);
            }
            System.out.println();
        }
    }

    /**
    * gets the next option found in the commandline. Distinguishes
    * between two bad cases, one case is when an illegal option
    * is found, and then other case is when an option takes an
    * argument but no argument was found for that option.
    * If the option found was not declared in the optString, then
    * an IllegalArgumentException will be thrown (case 1).
    * If the next option found has been declared to take an argument,
    * and no such argument exists, then a MissingOptArgException
    * is thrown (case 2).
    * @param none
    * @return int - the next option found.
    * @throws IllegalArgumentException, MissingOptArgException.
    */
    public int getNextOption() throws IllegalArgumentException,
        MissingOptArgException
    {
        int retval = -1;
        if(theOptionsIterator.hasNext()){
            theCurrentOption = (Option)theOptionsIterator.next();
            char c = theCurrentOption.getArgLetter();
            boolean shouldHaveArg = theOptionMatcher.hasArg(c);
            String arg = theCurrentOption.getArgument();
            if(!theOptionMatcher.match(c)) {
                ErrorMsg msg = new ErrorMsg(ErrorMsg.ILLEGAL_CMDLINE_OPTION_ERR,
                                            new Character(c));
                throw (new IllegalArgumentException(msg.toString()));
            }
            else if(shouldHaveArg && (arg == null)) {
                ErrorMsg msg = new ErrorMsg(ErrorMsg.CMDLINE_OPT_MISSING_ARG_ERR,
                                            new Character(c));
                throw (new MissingOptArgException(msg.toString()));
            }
            retval = c;
        }
        return retval;
    }

    /**
    * gets the argument for the current parsed option. For example,
    * in case of '-d <file>', if current option parsed is 'd' then
    * getOptionArg() would return '<file>'.
    * @return String - argument for current parsed option.
    * @param none
    */
    public String getOptionArg(){
        String retval = null;
        String tmp = theCurrentOption.getArgument();
        char c = theCurrentOption.getArgLetter();
        if(theOptionMatcher.hasArg(c)){
            retval = tmp;
        }
        return retval;
    }

    /**
    * gets list of the commandline arguments. For example, in command
    * such as 'cmd -s -d file file2 file3 file4'  with the usage
    * 'cmd [-s] [-d <file>] <file>...', getCmdArgs() would return
    * the list {file2, file3, file4}.
    * @return String[] - list of command arguments that may appear
    *                    after options and option arguments.
    * @params none
    */
    public String[] getCmdArgs(){
        String[] retval = new String[theCmdArgs.size()];
        int i=0;
        for(ListIterator it=theCmdArgs.listIterator(); it.hasNext();){
            retval[i++] = (String)it.next();
        }
        return retval;
    }


    private Option theCurrentOption = null;
    private ListIterator theOptionsIterator;
    private List theOptions = null;
    private List theCmdArgs = null;
    private OptionMatcher theOptionMatcher = null;

    ///////////////////////////////////////////////////////////
    //
    //   Inner Classes
    //
    ///////////////////////////////////////////////////////////

    // inner class to model an option
    class Option{
        private char theArgLetter;
        private String theArgument = null;
        public Option(char argLetter) { theArgLetter = argLetter; }
        public void setArg(String arg) {
            theArgument = arg;
        }
        public boolean hasArg() { return (theArgument != null); }
        public char getArgLetter() { return theArgLetter; }
        public String getArgument() { return theArgument; }
    } // end class Option


    // inner class to query optString for a possible option match,
    // and whether or not a given legal option takes an argument.
    //
    class OptionMatcher{
        public OptionMatcher(String optString){
            theOptString = optString;
        }
        public boolean match(char c){
            boolean retval = false;
            if(theOptString.indexOf(c) != -1){
                retval = true;
            }
            return retval;
        }
        public boolean hasArg(char c){
            boolean retval = false;
            int index = theOptString.indexOf(c)+1;
            if (index == theOptString.length()){
                // reached end of theOptString
                retval = false;
            }
            else if(theOptString.charAt(index) == ':'){
                retval = true;
            }
            return retval;
        }
        private String theOptString = null;
    } // end class OptionMatcher
}// end class GetOpt

⏎ com/sun/org/apache/xalan/internal/xsltc/cmdline/getopt/GetOpt.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
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