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/image/codec/jpeg/TruncatedFileException.java

/*
 *
 * Copyright (c) 2007, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

/* ********************************************************************
 **********************************************************************
 **********************************************************************
 *** COPYRIGHT (c) Eastman Kodak Company, 1997                      ***
 *** As  an unpublished  work pursuant to Title 17 of the United    ***
 *** States Code.  All rights reserved.                             ***
 **********************************************************************
 **********************************************************************
 **********************************************************************/

package com.sun.image.codec.jpeg;

import java.awt.image.Raster;
import java.awt.image.BufferedImage;
/**
 * Signals that a truncated file was detected.  This object contains
 * the Raster/BufferedImage that has the partially decoded image data
 * in it.  There is no indication of the portion of the Raster that
 * may or may not be good.
 * <p>
 * Note that the classes in the com.sun.image.codec.jpeg package are not
 * part of the core Java APIs.  They are a part of Sun's JDK and JRE
 * distributions.  Although other licensees may choose to distribute these
 * classes, developers cannot depend on their availability in non-Sun
 * implementations.  We expect that equivalent functionality will eventually
 * be available in a core API or standard extension.
 * <p>
 *
 * @author  Thomas DeWeese
 * @see     JPEGImageDecoder
 * @since   1.2
 */
public
class TruncatedFileException extends RuntimeException {
        private Raster                  ras = null;
        private BufferedImage   bi  = null;


    /**
     * Constructs a <code>TruncatedFileException</code> with the
     * partially decoded BufferedImage.
     *
     * @param   bi the partially decoded BufferedImage (may be null).
     * @since   1.2
     */
    public TruncatedFileException(BufferedImage bi) {
                super("Premature end of input file");
                this.bi  = bi;
                this.ras = bi.getData();
    }

    /**
     * Constructs an <code>TruncatedFileException</code> with the
     * partially decoded Raster
     *
     * @param   ras the partially decoded Raster (may be null).
     * @since   1.2
     */
    public TruncatedFileException(Raster ras) {
                super("Premature end of input file");
                this.ras = ras;
    }

        /** Allows access to the raster that was in the progress of being
         * decoded may be null, it is likely to be only partially filled
         * with image data.
     * @since   1.2
         */
        public Raster getRaster() { return ras; }

        /** Allows access to the BufferedImage that was in the progress of
         * being decoded, this may be null, it is likely to be only
         * partially filled with image data.
     * @since   1.2
         */
        public BufferedImage getBufferedImage() { return bi; }
}

⏎ com/sun/image/codec/jpeg/TruncatedFileException.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 

⇒ Backup JDK 8 Installation Directory

⇐ JRE 8 rt.jar - org.* Package Source Code

⇑ Download and Use JDK 8

⇑⇑ FAQ for JDK (Java Development Kit)