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/CommunicationException.java

/*
 * Copyright (c) 1999, 2007, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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package com.sun.jmx.snmp.daemon;

// java import
//
import java.io.PrintStream;
import java.io.PrintWriter;

/**
 * Represents exceptions raised due to communications problems,
 * for example when a managed object server is out of reach.<p>
 *
 * <p><b>This API is a Sun Microsystems internal API  and is subject
 * to change without notice.</b></p>
 */

public class CommunicationException extends javax.management.JMRuntimeException {

    /* Serial version */
    private static final long serialVersionUID = -2499186113233316177L;

    /**
     * Constructs a CommunicationException with a target exception.
     */
    public CommunicationException(Throwable target) {
        super(target.getMessage());
        initCause(target);
    }

    /**
     * Constructs a CommunicationException with a target exception
     * and a detail message.
     */
    public CommunicationException(Throwable target, String msg) {
        super(msg);
        initCause(target);
    }

    /**
     * Constructs a CommunicationException with a detail message.
     */
    public CommunicationException(String msg) {
        super(msg);
    }

    /**
     * Get the thrown target exception.
     */
    public Throwable getTargetException() {
        return getCause();
    }

}

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