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/LineBorder.java

/*
 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */
package javax.swing.border;

import java.awt.Graphics;
import java.awt.Insets;
import java.awt.Color;
import java.awt.Component;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.awt.geom.Path2D;
import java.awt.geom.Rectangle2D;
import java.awt.geom.RoundRectangle2D;
import java.beans.ConstructorProperties;

/**
 * A class which implements a line border of arbitrary thickness
 * and of a single color.
 * <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
 */
public class LineBorder extends AbstractBorder
{
    private static Border blackLine;
    private static Border grayLine;

    protected int thickness;
    protected Color lineColor;
    protected boolean roundedCorners;

    /** Convenience method for getting the Color.black LineBorder of thickness 1.
      */
    public static Border createBlackLineBorder() {
        if (blackLine == null) {
            blackLine = new LineBorder(Color.black, 1);
        }
        return blackLine;
    }

    /** Convenience method for getting the Color.gray LineBorder of thickness 1.
      */
    public static Border createGrayLineBorder() {
        if (grayLine == null) {
            grayLine = new LineBorder(Color.gray, 1);
        }
        return grayLine;
    }

    /**
     * Creates a line border with the specified color and a
     * thickness = 1.
     * @param color the color for the border
     */
    public LineBorder(Color color) {
        this(color, 1, false);
    }

    /**
     * Creates a line border with the specified color and thickness.
     * @param color the color of the border
     * @param thickness the thickness of the border
     */
    public LineBorder(Color color, int thickness)  {
        this(color, thickness, false);
    }

    /**
     * Creates a line border with the specified color, thickness,
     * and corner shape.
     * @param color the color of the border
     * @param thickness the thickness of the border
     * @param roundedCorners whether or not border corners should be round
     * @since 1.3
     */
    @ConstructorProperties({"lineColor", "thickness", "roundedCorners"})
    public LineBorder(Color color, int thickness, boolean roundedCorners)  {
        lineColor = color;
        this.thickness = thickness;
        this.roundedCorners = roundedCorners;
    }

    /**
     * Paints the border for the specified component with the
     * specified position and size.
     * @param c the component for which this border is being painted
     * @param g the paint graphics
     * @param x the x position of the painted border
     * @param y the y position of the painted border
     * @param width the width of the painted border
     * @param height the height of the painted border
     */
    public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
        if ((this.thickness > 0) && (g instanceof Graphics2D)) {
            Graphics2D g2d = (Graphics2D) g;

            Color oldColor = g2d.getColor();
            g2d.setColor(this.lineColor);

            Shape outer;
            Shape inner;

            int offs = this.thickness;
            int size = offs + offs;
            if (this.roundedCorners) {
                float arc = .2f * offs;
                outer = new RoundRectangle2D.Float(x, y, width, height, offs, offs);
                inner = new RoundRectangle2D.Float(x + offs, y + offs, width - size, height - size, arc, arc);
            }
            else {
                outer = new Rectangle2D.Float(x, y, width, height);
                inner = new Rectangle2D.Float(x + offs, y + offs, width - size, height - size);
            }
            Path2D path = new Path2D.Float(Path2D.WIND_EVEN_ODD);
            path.append(outer, false);
            path.append(inner, false);
            g2d.fill(path);
            g2d.setColor(oldColor);
        }
    }

    /**
     * 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.set(thickness, thickness, thickness, thickness);
        return insets;
    }

    /**
     * Returns the color of the border.
     */
    public Color getLineColor()     {
        return lineColor;
    }

    /**
     * Returns the thickness of the border.
     */
    public int getThickness()       {
        return thickness;
    }

    /**
     * Returns whether this border will be drawn with rounded corners.
     * @since 1.3
     */
    public boolean getRoundedCorners() {
        return roundedCorners;
    }

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

}

⏎ javax/swing/border/LineBorder.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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