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/MotifTreeUI.java

/*
 * Copyright (c) 1997, 2006, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
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 *
 *
 *
 *
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 *
 *
 *
 *
 *
 *
 *
 */

package com.sun.java.swing.plaf.motif;

import java.awt.*;
import java.awt.event.*;

import java.io.*;
import java.util.*;

import javax.swing.*;
import javax.swing.plaf.*;
import javax.swing.tree.*;
import javax.swing.plaf.basic.*;

/**
 * Motif rendition of the tree component.
 * <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 Jeff Dinkins
 */
public class MotifTreeUI extends BasicTreeUI
{
    static final int HALF_SIZE = 7;
    static final int SIZE = 14;

    /**
     * creates a UI object to represent a Motif Tree widget
     */
    public MotifTreeUI() {
        super();
    }

    public void installUI(JComponent c) {
        super.installUI(c);
    }

    // BasicTreeUI overrides

    protected void paintVerticalLine( Graphics g, JComponent c, int x, int top, int bottom )
      {
          if (tree.getComponentOrientation().isLeftToRight()) {
              g.fillRect( x, top, 2, bottom - top + 2 );
          } else {
              g.fillRect( x - 1, top, 2, bottom - top + 2 );
          }
      }

    protected void paintHorizontalLine( Graphics g, JComponent c, int y, int left, int right )
      {
          g.fillRect( left, y, right - left + 1, 2 );
      }


    /**
     * The minus sign button icon.
     * <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.
     */
    public static class MotifExpandedIcon implements Icon, Serializable {
        static Color bg;
        static Color fg;
        static Color highlight;
        static Color shadow;

        public MotifExpandedIcon() {
            bg = UIManager.getColor("Tree.iconBackground");
            fg = UIManager.getColor("Tree.iconForeground");
            highlight = UIManager.getColor("Tree.iconHighlight");
            shadow = UIManager.getColor("Tree.iconShadow");
        }

        public static Icon createExpandedIcon() {
            return new MotifExpandedIcon();
        }

        public void paintIcon(Component c, Graphics g, int x, int y) {
            g.setColor(highlight);
            g.drawLine(x, y, x+SIZE-1, y);
            g.drawLine(x, y+1, x, y+SIZE-1);

            g.setColor(shadow);
            g.drawLine(x+SIZE-1, y+1, x+SIZE-1, y+SIZE-1);
            g.drawLine(x+1, y+SIZE-1, x+SIZE-1, y+SIZE-1);

            g.setColor(bg);
            g.fillRect(x+1, y+1, SIZE-2, SIZE-2);

            g.setColor(fg);
            g.drawLine(x+3, y+HALF_SIZE-1, x+SIZE-4, y+HALF_SIZE-1);
            g.drawLine(x+3, y+HALF_SIZE, x+SIZE-4, y+HALF_SIZE);
        }

        public int getIconWidth() { return SIZE; }
        public int getIconHeight() { return SIZE; }
    }

    /**
     * The plus sign button icon.
     * <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.
     */
    public static class MotifCollapsedIcon extends MotifExpandedIcon {
        public static Icon createCollapsedIcon() {
            return new MotifCollapsedIcon();
        }

        public void paintIcon(Component c, Graphics g, int x, int y) {
            super.paintIcon(c, g, x, y);
            g.drawLine(x + HALF_SIZE-1, y + 3, x + HALF_SIZE-1, y + (SIZE - 4));
            g.drawLine(x + HALF_SIZE, y + 3, x + HALF_SIZE, y + (SIZE - 4));
        }
    }

    public static ComponentUI createUI(JComponent x) {
        return new MotifTreeUI();
    }

    /**
     * Returns the default cell renderer that is used to do the
     * stamping of each node.
     */
    public TreeCellRenderer createDefaultCellRenderer() {
        return new MotifTreeCellRenderer();
    }

}

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