/* * Copyright (c) 1997, 2008, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */  /* * The Original Code is HAT. The Initial Developer of the * Original Code is Bill Foote, with contributions from others * at JavaSoft/Sun. */ package com.sun.tools.hat.internal.model; import java.util.Enumeration;import java.util.Hashtable;  /** * * @author      Bill Foote */  /** * Represents a java "Thing".  A thing is anything that can be the value of * a field.  This includes JavaHeapObject, JavaObjectRef, and JavaValue. */ public abstract class JavaThing {     protected JavaThing() {    }     /**     * If this is a forward reference, figure out what it really     * refers to.     *     * @param snapshot  The snapshot this is for     * @param field     The field this thing represents.  If null, it is     *                  assumed this thing is an object (and never a value).     */    public JavaThing dereference(Snapshot shapshot, JavaField field) {        return this;    }      /**     * Are we the same type as other?     *     * @see JavaObject.isSameTypeAs()     */    public boolean isSameTypeAs(JavaThing other) {        return getClass() == other.getClass();    }    /**     * @return true iff this represents a heap-allocated object     */    abstract public boolean isHeapAllocated();     /**     * @return the size of this object, in bytes, including VM overhead     */    abstract public int getSize();     /**     * @return a human-readable string representation of this thing     */    abstract public String toString();     /**     * Compare our string representation to other's     * @see java.lang.String.compareTo()     */    public int compareTo(JavaThing other) {        return toString().compareTo(other.toString());    } }