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/border/EmptyBorder.java

/*
 * Copyright (c) 1997, 2013, 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 javax.swing.border;

import java.awt.Graphics;
import java.awt.Insets;
import java.awt.Rectangle;
import java.awt.Component;
import java.io.Serializable;
import java.beans.ConstructorProperties;

/**
 * A class which provides an empty, transparent border which
 * takes up space but does no drawing.
 * <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.  As of 1.4, support for long term storage
 * of all JavaBeans&trade;
 * has been added to the <code>java.beans</code> package.
 * Please see {@link java.beans.XMLEncoder}.
 *
 * @author David Kloba
 */
@SuppressWarnings("serial")
public class EmptyBorder extends AbstractBorder implements Serializable
{
    protected int left, right, top, bottom;

    /**
     * Creates an empty border with the specified insets.
     * @param top the top inset of the border
     * @param left the left inset of the border
     * @param bottom the bottom inset of the border
     * @param right the right inset of the border
     */
    public EmptyBorder(int top, int left, int bottom, int right)   {
        this.top = top;
        this.right = right;
        this.bottom = bottom;
        this.left = left;
    }

    /**
     * Creates an empty border with the specified insets.
     * @param borderInsets the insets of the border
     */
    @ConstructorProperties({"borderInsets"})
    public EmptyBorder(Insets borderInsets)   {
        this.top = borderInsets.top;
        this.right = borderInsets.right;
        this.bottom = borderInsets.bottom;
        this.left = borderInsets.left;
    }

    /**
     * Does no drawing by default.
     */
    public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
    }

    /**
     * Reinitialize the insets parameter with this Border's current Insets.
     * @param c the component for which this border insets value applies
     * @param insets the object to be reinitialized
     */
    public Insets getBorderInsets(Component c, Insets insets) {
        insets.left = left;
        insets.top = top;
        insets.right = right;
        insets.bottom = bottom;
        return insets;
    }

    /**
     * Returns the insets of the border.
     * @since 1.3
     */
    public Insets getBorderInsets() {
        return new Insets(top, left, bottom, right);
    }

    /**
     * Returns whether or not the border is opaque.
     * Returns false by default.
     */
    public boolean isBorderOpaque() { return false; }

}

⏎ javax/swing/border/EmptyBorder.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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