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/BerException.java

/*
 * Copyright (c) 1997, 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;





/**
 * Exception thrown when a BER encoding/decoding error occurs.
 *
 * <p><b>This API is a Sun Microsystems internal API  and is subject
 * to change without notice.</b></p>
 *
 * @since 1.5
 */

public class BerException extends Exception {
  private static final long serialVersionUID = 494709767137042951L;

  public static final int BAD_VERSION=1;

  private int errorType= 0;

  public BerException() {
    errorType= 0;
  }

  public BerException(int x) {
    errorType= x;
  }

  public boolean isInvalidSnmpVersion() {
    if (errorType == BAD_VERSION)
      return true;
    else
      return false;
  }
}

⏎ com/sun/jmx/snmp/BerException.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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