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/gtk/GTKIconFactory.java

/*
 * Copyright (c) 2002, 2006, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */
package com.sun.java.swing.plaf.gtk;

import java.util.*;
import javax.swing.plaf.synth.*;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.lang.reflect.*;
import javax.swing.*;
import javax.swing.plaf.*;
import sun.swing.plaf.synth.*;
import com.sun.java.swing.plaf.gtk.GTKConstants.ArrowType;
import com.sun.java.swing.plaf.gtk.GTKConstants.ExpanderStyle;
import com.sun.java.swing.plaf.gtk.GTKConstants.Orientation;
import com.sun.java.swing.plaf.gtk.GTKConstants.ShadowType;

/**
 */
class GTKIconFactory {
    static final int CHECK_ICON_EXTRA_INSET        = 1;
    static final int DEFAULT_ICON_SPACING          = 2;
    static final int DEFAULT_ICON_SIZE             = 13;
    static final int DEFAULT_TOGGLE_MENU_ITEM_SIZE = 12; // For pre-gtk2.4

    private static final String RADIO_BUTTON_ICON    = "paintRadioButtonIcon";
    private static final String CHECK_BOX_ICON       = "paintCheckBoxIcon";
    private static final String MENU_ARROW_ICON      = "paintMenuArrowIcon";
    private static final String CHECK_BOX_MENU_ITEM_CHECK_ICON =
                                      "paintCheckBoxMenuItemCheckIcon";
    private static final String RADIO_BUTTON_MENU_ITEM_CHECK_ICON =
                                      "paintRadioButtonMenuItemCheckIcon";
    private static final String TREE_EXPANDED_ICON = "paintTreeExpandedIcon";
    private static final String TREE_COLLAPSED_ICON = "paintTreeCollapsedIcon";
    private static final String ASCENDING_SORT_ICON = "paintAscendingSortIcon";
    private static final String DESCENDING_SORT_ICON = "paintDescendingSortIcon";
    private static final String TOOL_BAR_HANDLE_ICON = "paintToolBarHandleIcon";

    private static Map<String, DelegatingIcon> iconsPool =
            Collections.synchronizedMap(new HashMap<String, DelegatingIcon>());

    private static DelegatingIcon getIcon(String methodName) {
        DelegatingIcon result = iconsPool.get(methodName);
        if (result == null) {
            if (methodName == TREE_COLLAPSED_ICON ||
                methodName == TREE_EXPANDED_ICON)
            {
                result = new SynthExpanderIcon(methodName);

            } else if (methodName == TOOL_BAR_HANDLE_ICON) {
                result = new ToolBarHandleIcon();

            } else if (methodName == MENU_ARROW_ICON) {
                result = new MenuArrowIcon();

            } else {
                result = new DelegatingIcon(methodName);
            }
            iconsPool.put(methodName, result);
        }
        return result;
    }

    //
    // Sort arrow
    //
    public static Icon getAscendingSortIcon() {
        return getIcon(ASCENDING_SORT_ICON);
    }

    public static Icon getDescendingSortIcon() {
        return getIcon(DESCENDING_SORT_ICON);
    }

    //
    // Tree methods
    //
    public static SynthIcon getTreeExpandedIcon() {
        return getIcon(TREE_EXPANDED_ICON);
    }

    public static SynthIcon getTreeCollapsedIcon() {
        return getIcon(TREE_COLLAPSED_ICON);
    }

    //
    // Radio button
    //
    public static SynthIcon getRadioButtonIcon() {
        return getIcon(RADIO_BUTTON_ICON);
    }

    //
    // CheckBox
    //
    public static SynthIcon getCheckBoxIcon() {
        return getIcon(CHECK_BOX_ICON);
    }

    //
    // Menus
    //
    public static SynthIcon getMenuArrowIcon() {
        return getIcon(MENU_ARROW_ICON);
    }

    public static SynthIcon getCheckBoxMenuItemCheckIcon() {
        return getIcon(CHECK_BOX_MENU_ITEM_CHECK_ICON);
    }

    public static SynthIcon getRadioButtonMenuItemCheckIcon() {
        return getIcon(RADIO_BUTTON_MENU_ITEM_CHECK_ICON);
    }

    //
    // ToolBar Handle
    //
    public static SynthIcon getToolBarHandleIcon() {
        return getIcon(TOOL_BAR_HANDLE_ICON);
    }

    static void resetIcons() {
        synchronized (iconsPool) {
            for (DelegatingIcon di: iconsPool.values()) {
                di.resetIconDimensions();
            }
        }
    }

    private static class DelegatingIcon extends SynthIcon implements
                                   UIResource {
        private static final Class[] PARAM_TYPES = new Class[] {
            SynthContext.class, Graphics.class, int.class,
            int.class, int.class, int.class, int.class
        };

        private Object method;
        int iconDimension = -1;

        DelegatingIcon(String methodName ){
            this.method = methodName;
        }

        public void paintIcon(SynthContext context, Graphics g,
                              int x, int y, int w, int h) {
            if (context != null) {
                GTKPainter.INSTANCE.paintIcon(context, g,
                        getMethod(), x, y, w, h);
            }
        }

        public int getIconWidth(SynthContext context) {
            return getIconDimension(context);
        }

        public int getIconHeight(SynthContext context) {
            return getIconDimension(context);
        }

        void resetIconDimensions() {
            iconDimension = -1;
        }

        protected Method getMethod() {
            if (method instanceof String) {
                method = resolveMethod((String)method);
            }
            return (Method)method;
        }

        protected Class[] getMethodParamTypes() {
            return PARAM_TYPES;
        }

        private Method resolveMethod(String name) {
            try {
                return GTKPainter.class.getMethod(name, getMethodParamTypes());
            } catch (NoSuchMethodException e) {
                assert false;
            }
            return null;
        }

        int getIconDimension(SynthContext context) {
            if (iconDimension >= 0) {
                return iconDimension;
            }

            if (context == null) {
                return DEFAULT_ICON_SIZE;
            }

            Region region = context.getRegion();
            GTKStyle style = (GTKStyle) context.getStyle();
            iconDimension = style.getClassSpecificIntValue(context,
                    "indicator-size",
                    (region == Region.CHECK_BOX_MENU_ITEM ||
                     region == Region.RADIO_BUTTON_MENU_ITEM) ?
                        DEFAULT_TOGGLE_MENU_ITEM_SIZE : DEFAULT_ICON_SIZE);

            if (region == Region.CHECK_BOX || region == Region.RADIO_BUTTON) {
                iconDimension += 2 * style.getClassSpecificIntValue(context,
                        "indicator-spacing", DEFAULT_ICON_SPACING);
            } else if (region == Region.CHECK_BOX_MENU_ITEM ||
                       region == Region.RADIO_BUTTON_MENU_ITEM) {
                iconDimension += 2 * CHECK_ICON_EXTRA_INSET;
            }
            return iconDimension;
        }
    }

    private static class SynthExpanderIcon extends DelegatingIcon {
        SynthExpanderIcon(String method) {
            super(method);
        }

        public void paintIcon(SynthContext context, Graphics g, int x, int y,
                              int w, int h) {
            if (context != null) {
                super.paintIcon(context, g, x, y, w, h);
                updateSizeIfNecessary(context);
            }
        }

        int getIconDimension(SynthContext context) {
            updateSizeIfNecessary(context);
            return (iconDimension == -1) ? DEFAULT_ICON_SIZE :
                                           iconDimension;
        }

        private void updateSizeIfNecessary(SynthContext context) {
            if (iconDimension == -1 && context != null) {
                iconDimension = context.getStyle().getInt(context,
                        "Tree.expanderSize", 10);
            }
        }
    }

    // GTK has a separate widget for the handle box, to mirror this
    // we create a unique icon per ToolBar and lookup the style for the
    // HandleBox.
    private static class ToolBarHandleIcon extends DelegatingIcon {
        private static final Class[] PARAM_TYPES = new Class[] {
            SynthContext.class, Graphics.class, int.class,
            int.class, int.class, int.class, int.class, Orientation.class,
        };

        private SynthStyle style;

        public ToolBarHandleIcon() {
            super(TOOL_BAR_HANDLE_ICON);
        }

        protected Class[] getMethodParamTypes() {
            return PARAM_TYPES;
        }

        public void paintIcon(SynthContext context, Graphics g, int x, int y,
                              int w, int h) {
            if (context != null) {
                JToolBar toolbar = (JToolBar)context.getComponent();
                Orientation orientation =
                        (toolbar.getOrientation() == JToolBar.HORIZONTAL ?
                            Orientation.HORIZONTAL : Orientation.VERTICAL);

                if (style == null) {
                    style = SynthLookAndFeel.getStyleFactory().getStyle(
                            context.getComponent(), GTKRegion.HANDLE_BOX);
                }
                context = new SynthContext(toolbar, GTKRegion.HANDLE_BOX,
                        style, SynthConstants.ENABLED);

                GTKPainter.INSTANCE.paintIcon(context, g,
                        getMethod(), x, y, w, h, orientation);
            }
        }

        public int getIconWidth(SynthContext context) {
            if (context == null) {
                return 10;
            }
            if (((JToolBar)context.getComponent()).getOrientation() ==
                    JToolBar.HORIZONTAL) {
                return 10;
            } else {
                return context.getComponent().getWidth();
            }
        }

        public int getIconHeight(SynthContext context) {
            if (context == null) {
                return 10;
            }
            if (((JToolBar)context.getComponent()).getOrientation() ==
                    JToolBar.HORIZONTAL) {
                return context.getComponent().getHeight();
            } else {
                return 10;
            }
        }
    }

    private static class MenuArrowIcon extends DelegatingIcon {
        private static final Class[] PARAM_TYPES = new Class[] {
            SynthContext.class, Graphics.class, int.class,
            int.class, int.class, int.class, int.class, ArrowType.class,
        };

        public MenuArrowIcon() {
            super(MENU_ARROW_ICON);
        }

        protected Class[] getMethodParamTypes() {
            return PARAM_TYPES;
        }

        public void paintIcon(SynthContext context, Graphics g, int x, int y,
                              int w, int h) {
            if (context != null) {
                ArrowType arrowDir = ArrowType.RIGHT;
                if (!context.getComponent().getComponentOrientation().isLeftToRight()) {
                    arrowDir = ArrowType.LEFT;
                }
                GTKPainter.INSTANCE.paintIcon(context, g,
                        getMethod(), x, y, w, h, arrowDir);
            }
        }
    }
}

⏎ com/sun/java/swing/plaf/gtk/GTKIconFactory.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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