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/lang/model/type/TypeKind.java

/*
 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package javax.lang.model.type;


/**
 * The kind of a type mirror.
 *
 * <p>Note that it is possible additional type kinds will be added to
 * accommodate new, currently unknown, language structures added to
 * future versions of the Java&trade; programming language.
 *
 * @author Joseph D. Darcy
 * @author Scott Seligman
 * @author Peter von der Ah&eacute;
 * @see TypeMirror
 * @since 1.6
 */
public enum TypeKind {
    /**
     * The primitive type {@code boolean}.
     */
    BOOLEAN,

    /**
     * The primitive type {@code byte}.
     */
    BYTE,

    /**
     * The primitive type {@code short}.
     */
    SHORT,

    /**
     * The primitive type {@code int}.
     */
    INT,

    /**
     * The primitive type {@code long}.
     */
    LONG,

    /**
     * The primitive type {@code char}.
     */
    CHAR,

    /**
     * The primitive type {@code float}.
     */
    FLOAT,

    /**
     * The primitive type {@code double}.
     */
    DOUBLE,

    /**
     * The pseudo-type corresponding to the keyword {@code void}.
     * @see NoType
     */
    VOID,

    /**
     * A pseudo-type used where no actual type is appropriate.
     * @see NoType
     */
    NONE,

    /**
     * The null type.
     */
    NULL,

    /**
     * An array type.
     */
    ARRAY,

    /**
     * A class or interface type.
     */
    DECLARED,

    /**
     * A class or interface type that could not be resolved.
     */
    ERROR,

    /**
     * A type variable.
     */
    TYPEVAR,

    /**
     * A wildcard type argument.
     */
    WILDCARD,

    /**
     * A pseudo-type corresponding to a package element.
     * @see NoType
     */
    PACKAGE,

    /**
     * A method, constructor, or initializer.
     */
    EXECUTABLE,

    /**
     * An implementation-reserved type.
     * This is not the type you are looking for.
     */
    OTHER,

    /**
      * A union type.
      *
      * @since 1.7
      */
    UNION,

    /**
      * An intersection type.
      *
      * @since 1.8
      */
    INTERSECTION;

    /**
     * Returns {@code true} if this kind corresponds to a primitive
     * type and {@code false} otherwise.
     * @return {@code true} if this kind corresponds to a primitive type
     */
    public boolean isPrimitive() {
        switch(this) {
        case BOOLEAN:
        case BYTE:
        case SHORT:
        case INT:
        case LONG:
        case CHAR:
        case FLOAT:
        case DOUBLE:
            return true;

        default:
            return false;
        }
    }
}

⏎ javax/lang/model/type/TypeKind.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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