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/annotation/processing/FilerException.java

/*
 * Copyright (c) 2005, 2012, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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package javax.annotation.processing;

import java.io.IOException;

/**
 * Indicates a {@link Filer} detected an attempt to open a file that
 * would violate the guarantees provided by the {@code Filer}.  Those
 * guarantees include not creating the same file more than once, not
 * creating multiple files corresponding to the same type, and not
 * creating files for types with invalid names.
 *
 * @author Joseph D. Darcy
 * @author Scott Seligman
 * @author Peter von der Ahé
 * @since 1.6
 */
public class FilerException extends IOException {
    static final long serialVersionUID = 8426423106453163293L;
    /**
     * Constructs an exception with the specified detail message.
     * @param s the detail message, which should include the name of
     * the file attempting to be opened; may be {@code null}
     */
    public FilerException(String s) {
        super(s);
    }
}

⏎ javax/annotation/processing/FilerException.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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