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 java.* package in JRE 1.8.0_191 rt.jar. Java source codes are also provided.

⏎ java/awt/ColorPaintContext.java

/*
 * Copyright (c) 1997, 2007, 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 java.awt;

import java.awt.image.ColorModel;
import java.awt.image.Raster;
import java.awt.image.WritableRaster;
import sun.awt.image.IntegerComponentRaster;
import java.util.Arrays;

class ColorPaintContext implements PaintContext {
    int color;
    WritableRaster savedTile;

    protected ColorPaintContext(int color, ColorModel cm) {
        this.color = color;
    }

    public void dispose() {
    }

    /*
     * Returns the RGB value representing the color in the default sRGB
     * {@link ColorModel}.
     * (Bits 24-31 are alpha, 16-23 are red, 8-15 are green, 0-7 are
     * blue).
     * @return the RGB value of the color in the default sRGB
     *         <code>ColorModel</code>.
     * @see java.awt.image.ColorModel#getRGBdefault
     * @see #getRed
     * @see #getGreen
     * @see #getBlue
     */
    int getRGB() {
        return color;
    }

    public ColorModel getColorModel() {
        return ColorModel.getRGBdefault();
    }

    public synchronized Raster getRaster(int x, int y, int w, int h) {
        WritableRaster t = savedTile;

        if (t == null || w > t.getWidth() || h > t.getHeight()) {
            t = getColorModel().createCompatibleWritableRaster(w, h);
            IntegerComponentRaster icr = (IntegerComponentRaster) t;
            Arrays.fill(icr.getDataStorage(), color);
            // Note - markDirty is probably unnecessary since icr is brand new
            icr.markDirty();
            if (w <= 64 && h <= 64) {
                savedTile = t;
            }
        }

        return t;
    }
}

⏎ java/awt/ColorPaintContext.java

Or download all of them as a single archive file:

File name: jre-rt-java-1.8.0_191-src.zip
File size: 6664831 bytes
Release date: 2018-10-28
Download 

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