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/swing/plaf/synth/SynthComboPopup.java

/*
 * Copyright (c) 2002, 2012, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
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 *
 *
 *
 *
 *
 *
 *
 *
 */

package javax.swing.plaf.synth;

import javax.swing.*;
import javax.swing.plaf.ComboBoxUI;
import javax.swing.plaf.basic.BasicComboPopup;
import java.awt.*;


/**
 * Synth's ComboPopup.
 *
 * @author Scott Violet
 */
class SynthComboPopup extends BasicComboPopup {
    public SynthComboPopup( JComboBox combo ) {
        super(combo);
    }

    /**
     * Configures the list which is used to hold the combo box items in the
     * popup. This method is called when the UI class
     * is created.
     *
     * @see #createList
     */
    @Override
    protected void configureList() {
        list.setFont( comboBox.getFont() );
        list.setCellRenderer( comboBox.getRenderer() );
        list.setFocusable( false );
        list.setSelectionMode( ListSelectionModel.SINGLE_SELECTION );
        int selectedIndex = comboBox.getSelectedIndex();
        if ( selectedIndex == -1 ) {
            list.clearSelection();
        }
        else {
            list.setSelectedIndex( selectedIndex );
            list.ensureIndexIsVisible( selectedIndex );
        }
        installListListeners();
    }

    /**
     * @inheritDoc
     *
     * Overridden to take into account any popup insets specified in
     * SynthComboBoxUI
     */
    @Override
    protected Rectangle computePopupBounds(int px, int py, int pw, int ph) {
        ComboBoxUI ui = comboBox.getUI();
        if (ui instanceof SynthComboBoxUI) {
            SynthComboBoxUI sui = (SynthComboBoxUI) ui;
            if (sui.popupInsets != null) {
                Insets i = sui.popupInsets;
                return super.computePopupBounds(
                        px + i.left,
                        py + i.top,
                        pw - i.left - i.right,
                        ph - i.top - i.bottom);
            }
        }
        return super.computePopupBounds(px, py, pw, ph);
    }
}

⏎ javax/swing/plaf/synth/SynthComboPopup.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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