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/jmx/snmp/daemon/SnmpRequestCounter.java

/*
 *
 * Copyright (c) 2007, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
// Copyright (c) 1995-96 by Cisco Systems, Inc.

package com.sun.jmx.snmp.daemon;

/**
 * A static instance of this class is usually created.  It contains a
 * counter that is incremented every time it is accessed.  For example,
 * this class can be used in <CODE>SnmpSession</CODE> to generate a request
 * identifier that is used to identify a message in a client-server session.
 * The class wraps around when it reaches the maximum positive value, 2^31 - 1.
 */

final class SnmpRequestCounter {
        /**
         * A counter with value between 1...2^31-1.
         */
        int reqid = 0 ;

        public SnmpRequestCounter() {}

        /**
         * Returns the next request identifier.
         * @return next request identifier.  The value wraps to 1 if it reaches negative value.
         */
        public synchronized int getNewId() {
                if (++reqid  < 0)
                        reqid = 1 ;
                return reqid ;
        }
}

⏎ com/sun/jmx/snmp/daemon/SnmpRequestCounter.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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