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/imageio/plugins/common/SubImageInputStream.java

/*
 * Copyright (c) 2000, 2005, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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package com.sun.imageio.plugins.common;

import java.io.IOException;
import javax.imageio.stream.ImageInputStreamImpl;
import javax.imageio.stream.ImageInputStream;

public final class SubImageInputStream extends ImageInputStreamImpl {

    ImageInputStream stream;
    long startingPos;
    int startingLength;
    int length;

    public SubImageInputStream(ImageInputStream stream, int length)
        throws IOException {
        this.stream = stream;
        this.startingPos = stream.getStreamPosition();
        this.startingLength = this.length = length;
    }

    public int read() throws IOException {
        if (length == 0) { // Local EOF
            return -1;
        } else {
            --length;
            return stream.read();
        }
    }

    public int read(byte[] b, int off, int len) throws IOException {
        if (length == 0) { // Local EOF
            return -1;
        }

        len = Math.min(len, length);
        int bytes = stream.read(b, off, len);
        length -= bytes;
        return bytes;
    }

    public long length() {
        return startingLength;
    }

    public void seek(long pos) throws IOException {
        stream.seek(pos - startingPos);
        streamPos = pos;
    }

    protected void finalize() throws Throwable {
        // Empty finalizer (for improved performance; no need to call
        // super.finalize() in this case)
    }
}

⏎ com/sun/imageio/plugins/common/SubImageInputStream.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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