/** * $RCSfile: CacheSizes.java,v $ * $Revision: 1.2 $ * $Date: 2002/08/15 23:17:21 $ * * Copyright (C) 1999-2002 CoolServlets, Inc. All rights reserved. * * This software is the proprietary information of CoolServlets, Inc. * Use is subject to license terms. */package com.struts2.framework.util;import java.util.*;/** * Utility class for determining the sizes in bytes of commonly used objects. * Classes implementing the Cacheable interface should use this class to * determine their size. * * @author Matt Tucker */public class CacheSizes {    /**     * Returns the size in bytes of a basic Object. This method should only     * be used for actual Object objects and not classes that extend Object.     *     * @return the size of an Object.     */    public static int sizeOfObject() {        return 4;    }    /**     * Returns the size in bytes of a String.     *     * @param string the String to determine the size of.     * @return the size of a String.     */    public static int sizeOfString(String string) {        if (string == null) {            return 0;        }        return 4 + string.length()*2;    }    /**     * Returns the size in bytes of a primitive int.     *     * @return the size of a primitive int.     */    public static int sizeOfInt() {        return 4;    }    /**     * Returns the size in bytes of a primitive char.     *     * @return the size of a primitive char.     */    public static int sizeOfChar() {        return 2;    }    /**     * Returns the size in bytes of a primitive boolean.     *     * @return the size of a primitive boolean.     */    public static int sizeOfBoolean() {        return 1;    }    /**     * Returns the size in bytes of a primitive long.     *     * @return the size of a primitive long.     */    public static int sizeOfLong() {        return 8;    }    /**     * Returns the size in bytes of a primitive double.     *     * @return the size of a primitive double.     */    public static int sizeOfDouble() {        return 8;    }    /**     * Returns the size in bytes of a Date.     *     * @return the size of a Date.     */    public static int sizeOfDate() {        return 12;    }    /**     * Returns the size in bytes of a Map object. All keys and     * values <b>must be Strings</b>.     *     * @param map the Map object to determine the size of.     * @return the size of the Map object.     */    public static int sizeOfMap(Map map) {        if (map == null) {            return 0;        }        // Base map object -- should be something around this size.        int size = 36;        // Add in size of each value        Object []  values = map.values().toArray();        for (int i=0; i<values.length; i++) {            size += sizeOfString((String)values[i]);        }        Object [] keys = map.keySet().toArray();        // Add in each key        for (int i=0; i<keys.length; i++) {            size += sizeOfString((String)keys[i]);        }        return size;    }    /**     * Returns the size in bytes of a List object. Elements are assumed to be     * <tt>String</tt>s, <tt>Long</tt>s or <tt>Cacheable</tt> objects.     *     * @param list the List object to determine the size of.     * @return the size of the List object.     */    public static int sizeOfList(List list) {        if (list == null) {            return 0;        }        // Base list object (approximate)        int size = 36;        // Add in size of each value        Object []  values = list.toArray();        for (int i=0; i<values.length; i++) {            Object obj = values[i];            if (obj instanceof String) {                size += sizeOfString((String)obj);            }            else if (obj instanceof Long) {                size += sizeOfLong() + sizeOfObject();            }            else {                size += ((Cacheable)obj).getCachedSize();            }        }        return size;    }}