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Java > Open Source Codes > com > sun > org > apache > bcel > internal > classfile > ConstantClass


1 package com.sun.org.apache.bcel.internal.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 com.sun.org.apache.bcel.internal.Constants;
58 import java.io.*;
59
60 /**
61  * This class is derived from the abstract
62  * <A HREF="com.sun.org.apache.bcel.internal.classfile.Constant.html">Constant</A> class
63  * and represents a reference to a (external) class.
64  *
65  * @version $Id: ConstantClass.java,v 1.1.1.1 2001/10/29 19:59:58 jvanzyl Exp $
66  * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
67  * @see Constant
68  */
69 public final class ConstantClass extends Constant implements ConstantObject {
70   private int name_index; // Identical to ConstantString except for the name
71
72   /**
73    * Initialize from another object.
74    */
75   public ConstantClass(ConstantClass c) {
76     this(c.getNameIndex());
77   }
78
79   /**
80    * Initialize instance from file data.
81    *
82    * @param file Input stream
83    * @throw IOException
84    */
85   ConstantClass(DataInputStream file) throws IOException
86   {
87     this(file.readUnsignedShort());
88   }
89
90   /**
91    * @param name_index Name index in constant pool
92    */
93   public ConstantClass(int name_index) {
94     super(Constants.CONSTANT_Class);
95     this.name_index = name_index;
96   }
97
98   /**
99    * Called by objects that are traversing the nodes of the tree implicitely
100    * defined by the contents of a Java class. I.e., the hierarchy of methods,
101    * fields, attributes, etc. spawns a tree of objects.
102    *
103    * @param v Visitor object
104    */
105   public void accept(Visitor v) {
106     v.visitConstantClass(this);
107   }
108
109   /**
110    * Dump constant class to file stream in binary format.
111    *
112    * @param file Output file stream
113    * @throw IOException
114    */
115   public final void dump(DataOutputStream file) throws IOException
116   {
117     file.writeByte(tag);
118     file.writeShort(name_index);
119   }
120
121   /**
122    * @return Name index in constant pool of class name.
123    */
124   public final int getNameIndex() { return name_index; }
125
126   /**
127    * @param name_index.
128    */
129   public final void setNameIndex(int name_index) {
130     this.name_index = name_index;
131   }
132
133
134   /** @return String object
135    */
136   public Object JavaDoc getConstantValue(ConstantPool cp) {
137     Constant c = cp.getConstant(name_index, Constants.CONSTANT_Utf8);
138     return ((ConstantUtf8)c).getBytes();
139   }
140
141   /** @return dereferenced string
142    */
143   public String JavaDoc getBytes(ConstantPool cp) {
144     return (String JavaDoc)getConstantValue(cp);
145   }
146
147   /**
148    * @return String representation.
149    */
150   public final String JavaDoc toString() {
151     return super.toString() + "(name_index = " + name_index + ")";
152   }
153 }
154
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