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 javax.* package in JRE 1.8.0_191 rt.jar. Java source codes are also provided.

⏎ javax/imageio/event/IIOWriteWarningListener.java

/*
 * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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package javax.imageio.event;

import java.util.EventListener;
import javax.imageio.ImageWriter;

/**
 * An interface used by <code>ImageWriter</code> implementations to
 * notify callers of their image and thumbnail reading methods of
 * warnings (non-fatal errors).  Fatal errors cause the relevant
 * read method to throw an <code>IIOException</code>.
 *
 * <p> Localization is handled by associating a <code>Locale</code>
 * with each <code>IIOWriteWarningListener</code> as it is registered
 * with an <code>ImageWriter</code>.  It is up to the
 * <code>ImageWriter</code> to provide localized messages.
 *
 * @see javax.imageio.ImageWriter#addIIOWriteWarningListener
 * @see javax.imageio.ImageWriter#removeIIOWriteWarningListener
 *
 */
public interface IIOWriteWarningListener extends EventListener {

    /**
     * Reports the occurrence of a non-fatal error in encoding.  Encoding
     * will continue following the call to this method.  The application
     * may choose to display a dialog, print the warning to the console,
     * ignore the warning, or take any other action it chooses.
     *
     * @param source the <code>ImageWriter</code> object calling this method.
     * @param imageIndex the index, starting with 0, of the image
     * generating the warning.
     * @param warning a <code>String</code> containing the warning.
     */
    void warningOccurred(ImageWriter source,
                         int imageIndex,
                         String warning);
}

⏎ javax/imageio/event/IIOWriteWarningListener.java

Or download all of them as a single archive file:

File name: jre-rt-javax-1.8.0_191-src.zip
File size: 5381005 bytes
Release date: 2018-10-28
Download 

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

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

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