JavaThing.java revision 2224:2a8815d86b93 
1/*
2 * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26
27/*
28 * The Original Code is HAT. The Initial Developer of the
29 * Original Code is Bill Foote, with contributions from others
30 * at JavaSoft/Sun.
31 */
32
33package jdk.test.lib.hprof.model;
34
35import java.util.Enumeration;
36import java.util.Hashtable;
37
38
39/**
40 *
41 * @author      Bill Foote
42 */
43
44
45/**
46 * Represents a java "Thing".  A thing is anything that can be the value of
47 * a field.  This includes JavaHeapObject, JavaObjectRef, and JavaValue.
48 */
49
50public abstract class JavaThing {
51
52    protected JavaThing() {
53    }
54
55    /**
56     * If this is a forward reference, figure out what it really
57     * refers to.
58     *
59     * @param snapshot  The snapshot this is for
60     * @param field     The field this thing represents.  If null, it is
61     *                  assumed this thing is an object (and never a value).
62     */
63    public JavaThing dereference(Snapshot shapshot, JavaField field) {
64        return this;
65    }
66
67
68    /**
69     * Are we the same type as other?
70     *
71     * @see JavaObject.isSameTypeAs()
72     */
73    public boolean isSameTypeAs(JavaThing other) {
74        return getClass() == other.getClass();
75    }
76    /**
77     * @return true iff this represents a heap-allocated object
78     */
79    abstract public boolean isHeapAllocated();
80
81    /**
82     * @return the size of this object, in bytes, including VM overhead
83     */
84    abstract public int getSize();
85
86    /**
87     * @return a human-readable string representation of this thing
88     */
89    abstract public String toString();
90
91    /**
92     * Compare our string representation to other's
93     * @see java.lang.String.compareTo()
94     */
95    public int compareTo(JavaThing other) {
96        return toString().compareTo(other.toString());
97    }
98
99}
100