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

⏎ java/awt/Stroke.java

/*
 * Copyright (c) 1996, 1999, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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package java.awt;

/**
 * The <code>Stroke</code> interface allows a
 * {@link Graphics2D} object to obtain a {@link Shape} that is the
 * decorated outline, or stylistic representation of the outline,
 * of the specified <code>Shape</code>.
 * Stroking a <code>Shape</code> is like tracing its outline with a
 * marking pen of the appropriate size and shape.
 * The area where the pen would place ink is the area enclosed by the
 * outline <code>Shape</code>.
 * <p>
 * The methods of the <code>Graphics2D</code> interface that use the
 * outline <code>Shape</code> returned by a <code>Stroke</code> object
 * include <code>draw</code> and any other methods that are
 * implemented in terms of that method, such as
 * <code>drawLine</code>, <code>drawRect</code>,
 * <code>drawRoundRect</code>, <code>drawOval</code>,
 * <code>drawArc</code>, <code>drawPolyline</code>,
 * and <code>drawPolygon</code>.
 * <p>
 * The objects of the classes implementing <code>Stroke</code>
 * must be read-only because <code>Graphics2D</code> does not
 * clone these objects either when they are set as an attribute
 * with the <code>setStroke</code> method or when the
 * <code>Graphics2D</code> object is itself cloned.
 * If a <code>Stroke</code> object is modified after it is set in
 * the <code>Graphics2D</code> context then the behavior
 * of subsequent rendering would be undefined.
 * @see BasicStroke
 * @see Graphics2D#setStroke
 */
public interface Stroke {
    /**
     * Returns an outline <code>Shape</code> which encloses the area that
     * should be painted when the <code>Shape</code> is stroked according
     * to the rules defined by the
     * object implementing the <code>Stroke</code> interface.
     * @param p a <code>Shape</code> to be stroked
     * @return the stroked outline <code>Shape</code>.
     */
    Shape createStrokedShape (Shape p);
}

⏎ java/awt/Stroke.java

Or download all of them as a single archive file:

File name: jre-rt-java-1.8.0_191-src.zip
File size: 6664831 bytes
Release date: 2018-10-28
Download 

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