1 package org.apache.bcel.classfile;
2
3 /* ====================================================================
4 * The Apache Software License, Version 1.1
5 *
6 * Copyright (c) 2001 The Apache Software Foundation. All rights
7 * reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 *
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in
18 * the documentation and/or other materials provided with the
19 * distribution.
20 *
21 * 3. The end-user documentation included with the redistribution,
22 * if any, must include the following acknowledgment:
23 * "This product includes software developed by the
24 * Apache Software Foundation (http://www.apache.org/)."
25 * Alternately, this acknowledgment may appear in the software itself,
26 * if and wherever such third-party acknowledgments normally appear.
27 *
28 * 4. The names "Apache" and "Apache Software Foundation" and
29 * "Apache BCEL" must not be used to endorse or promote products
30 * derived from this software without prior written permission. For
31 * written permission, please contact apache@apache.org.
32 *
33 * 5. Products derived from this software may not be called "Apache",
34 * "Apache BCEL", nor may "Apache" appear in their name, without
35 * prior written permission of the Apache Software Foundation.
36 *
37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48 * SUCH DAMAGE.
49 * ====================================================================
50 *
51 * This software consists of voluntary contributions made by many
52 * individuals on behalf of the Apache Software Foundation. For more
53 * information on the Apache Software Foundation, please see
54 * <http://www.apache.org/>.
55 */
56
57 import org.apache.bcel.Constants;
58 import java.io.*;
59
60 /***
61 * This class is derived from the abstract
62 * <A HREF="org.apache.bcel.classfile.Constant.html">Constant</A> class
63 * and represents a reference to a String object.
64 *
65 * @version $Id: ConstantString.java,v 1.2 2002/03/11 16:16:35 mdahm Exp $
66 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
67 * @see Constant
68 */
69 public final class ConstantString extends Constant implements ConstantObject {
70 private int string_index; // Identical to ConstantClass except for this name
71
72 /***
73 * Initialize from another object.
74 */
75 public ConstantString(ConstantString c) {
76 this(c.getStringIndex());
77 }
78 /***
79 * Initialize instance from file data.
80 *
81 * @param file Input stream
82 * @throws IOException
83 */
84 ConstantString(DataInputStream file) throws IOException
85 {
86 this((int)file.readUnsignedShort());
87 }
88 /***
89 * @param string_index Index of Constant_Utf8 in constant pool
90 */
91 public ConstantString(int string_index)
92 {
93 super(Constants.CONSTANT_String);
94 this.string_index = string_index;
95 }
96 /***
97 * Called by objects that are traversing the nodes of the tree implicitely
98 * defined by the contents of a Java class. I.e., the hierarchy of methods,
99 * fields, attributes, etc. spawns a tree of objects.
100 *
101 * @param v Visitor object
102 */
103 public void accept(Visitor v) {
104 v.visitConstantString(this);
105 }
106 /***
107 * Dump constant field reference to file stream in binary format.
108 *
109 * @param file Output file stream
110 * @throws IOException
111 */
112 public final void dump(DataOutputStream file) throws IOException
113 {
114 file.writeByte(tag);
115 file.writeShort(string_index);
116 }
117 /***
118 * @return Index in constant pool of the string (ConstantUtf8).
119 */
120 public final int getStringIndex() { return string_index; }
121 /***
122 * @param string_index.
123 */
124 public final void setStringIndex(int string_index) {
125 this.string_index = string_index;
126 }
127 /***
128 * @return String representation.
129 */
130 public final String toString()
131 {
132 return super.toString() + "(string_index = " + string_index + ")";
133 }
134
135 /*** @return String object
136 */
137 public Object getConstantValue(ConstantPool cp) {
138 Constant c = cp.getConstant(string_index, Constants.CONSTANT_Utf8);
139 return ((ConstantUtf8)c).getBytes();
140 }
141
142 /*** @return dereferenced string
143 */
144 public String getBytes(ConstantPool cp) {
145 return (String)getConstantValue(cp);
146 }
147 }
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