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

⏎ com/sun/java/swing/plaf/motif/MotifScrollBarUI.java

/*
 * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
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 */
package com.sun.java.swing.plaf.motif;

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Insets;
import java.awt.Rectangle;

import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JScrollBar;
import javax.swing.plaf.ComponentUI;
import javax.swing.plaf.basic.BasicScrollBarUI;

import static sun.swing.SwingUtilities2.drawHLine;
import static sun.swing.SwingUtilities2.drawVLine;


/**
 * Implementation of ScrollBarUI for the Motif Look and Feel
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases.  The current serialization support is appropriate
 * for short term storage or RMI between applications running the same
 * version of Swing.  A future release of Swing will provide support for
 * long term persistence.
 *
 * @author Rich Schiavi
 * @author Hans Muller
 */
public class MotifScrollBarUI extends BasicScrollBarUI
{

    public static ComponentUI createUI(JComponent c) {
        return new MotifScrollBarUI();
    }

    public Dimension getPreferredSize(JComponent c) {
        Insets insets = c.getInsets();
        int dx = insets.left + insets.right;
        int dy = insets.top + insets.bottom;
        return (scrollbar.getOrientation() == JScrollBar.VERTICAL)
            ? new Dimension(dx + 11, dy + 33)
            : new Dimension(dx + 33, dy + 11);
    }

    protected JButton createDecreaseButton(int orientation) {
        return new MotifScrollBarButton(orientation);
    }

    protected JButton createIncreaseButton(int orientation) {
        return new MotifScrollBarButton(orientation);
    }

    public void paintTrack(Graphics g, JComponent c, Rectangle trackBounds)  {
        g.setColor(trackColor);
        g.fillRect(trackBounds.x, trackBounds.y, trackBounds.width, trackBounds.height);
    }

    public void paintThumb(Graphics g, JComponent c, Rectangle thumbBounds) {
        if (thumbBounds.isEmpty() || !scrollbar.isEnabled()) {
            return;
        }

        int w = thumbBounds.width;
        int h = thumbBounds.height;

        g.translate(thumbBounds.x, thumbBounds.y);
        g.setColor(thumbColor);
        g.fillRect(0, 0, w - 1, h - 1);

        g.setColor(thumbHighlightColor);
        drawVLine(g, 0, 0, h - 1);
        drawHLine(g, 1, w - 1, 0);

        g.setColor(thumbLightShadowColor);
        drawHLine(g, 1, w - 1, h - 1);
        drawVLine(g, w - 1, 1, h - 2);

        g.translate(-thumbBounds.x, -thumbBounds.y);
    }
}

⏎ com/sun/java/swing/plaf/motif/MotifScrollBarUI.java

Or download all of them as a single archive file:

File name: jre-rt-com-1.8.0_191-src.zip
File size: 8099783 bytes
Release date: 2018-10-28
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