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/accessibility/AccessibleExtendedTable.java

/*
 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package javax.accessibility;

/**
  * Class AccessibleExtendedTable provides extended information about
  * a user-interface component that presents data in a two-dimensional
  * table format.
  * Applications can determine if an object supports the
  * AccessibleExtendedTable interface by first obtaining its
  * AccessibleContext and then calling the
  * {@link AccessibleContext#getAccessibleTable} method.
  * If the return value is not null and the type of the return value is
  * AccessibleExtendedTable, the object supports this interface.
  *
  * @author      Lynn Monsanto
  * @since 1.4
  */
public interface AccessibleExtendedTable extends AccessibleTable {

     /**
      * Returns the row number of an index in the table.
      *
      * @param index the zero-based index in the table.  The index is
      * the table cell offset from row == 0 and column == 0.
      * @return the zero-based row of the table if one exists;
      * otherwise -1.
      */
     public int getAccessibleRow(int index);

     /**
      * Returns the column number of an index in the table.
      *
      * @param index the zero-based index in the table.  The index is
      * the table cell offset from row == 0 and column == 0.
      * @return the zero-based column of the table if one exists;
      * otherwise -1.
      */
     public int getAccessibleColumn(int index);

    /**
      * Returns the index at a row and column in the table.
      *
      * @param r zero-based row of the table
      * @param c zero-based column of the table
      * @return the zero-based index in the table if one exists;
      * otherwise -1.  The index is  the table cell offset from
      * row == 0 and column == 0.
      */
     public int getAccessibleIndex(int r, int c);
}

⏎ javax/accessibility/AccessibleExtendedTable.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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