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/MotifPopupMenuUI.java

/*
 * Copyright (c) 1997, 2005, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

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

import sun.swing.SwingUtilities2;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.border.*;
import java.awt.Color;
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Insets;
import java.awt.LayoutManager;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.*;
import javax.swing.plaf.*;
import javax.swing.plaf.basic.BasicPopupMenuUI;


/**
 * A Motif L&F implementation of PopupMenuUI.
 * <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 Georges Saab
 * @author Rich Schiavi
 */
public class MotifPopupMenuUI extends BasicPopupMenuUI {
    private static Border border = null;
    private Font titleFont = null;

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

    /* This has to deal with the fact that the title may be wider than
       the widest child component.
       */
    public Dimension getPreferredSize(JComponent c) {
        LayoutManager layout = c.getLayout();
        Dimension d = layout.preferredLayoutSize(c);
        String title = ((JPopupMenu)c).getLabel();
        if (titleFont == null) {
            UIDefaults table = UIManager.getLookAndFeelDefaults();
            titleFont = table.getFont("PopupMenu.font");
        }
        FontMetrics fm = c.getFontMetrics(titleFont);
        int         stringWidth = 0;

        if (title!=null) {
            stringWidth += SwingUtilities2.stringWidth(c, fm, title);
        }

        if (d.width < stringWidth) {
            d.width = stringWidth + 8;
            Insets i = c.getInsets();
            if (i!=null) {
                d.width += i.left + i.right;
            }
            if (border != null) {
                i = border.getBorderInsets(c);
                d.width += i.left + i.right;
            }

            return d;
        }
        return null;
    }

    protected ChangeListener createChangeListener(JPopupMenu m) {
        return new ChangeListener() {
            public void stateChanged(ChangeEvent e) {}
        };
    }

    public boolean isPopupTrigger(MouseEvent e) {
        return ((e.getID()==MouseEvent.MOUSE_PRESSED)
                && ((e.getModifiers() & MouseEvent.BUTTON3_MASK)!=0));
    }
}

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