1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.bcel.classfile;
18
19 import java.io.DataInput;
20 import java.io.DataOutputStream;
21 import java.io.IOException;
22
23 import org.apache.bcel.Const;
24
25 /**
26 * This class is derived from the abstract {@link Constant} and represents a reference to a (external) class.
27 *
28 * @see Constant
29 */
30 public final class ConstantClass extends Constant implements ConstantObject {
31
32 private int nameIndex; // Identical to ConstantString except for the name
33
34 /**
35 * Initialize from another object.
36 *
37 * @param c Source to copy.
38 */
39 public ConstantClass(final ConstantClass c) {
40 this(c.getNameIndex());
41 }
42
43 /**
44 * Constructs an instance from file data.
45 *
46 * @param dataInput Input stream
47 * @throws IOException if an I/O error occurs reading from the given {@code dataInput}.
48 */
49 ConstantClass(final DataInput dataInput) throws IOException {
50 this(dataInput.readUnsignedShort());
51 }
52
53 /**
54 * @param nameIndex Name index in constant pool. Should refer to a ConstantUtf8.
55 */
56 public ConstantClass(final int nameIndex) {
57 super(Const.CONSTANT_Class);
58 this.nameIndex = nameIndex;
59 }
60
61 /**
62 * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
63 * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
64 *
65 * @param v Visitor object
66 */
67 @Override
68 public void accept(final Visitor v) {
69 v.visitConstantClass(this);
70 }
71
72 /**
73 * Dumps constant class to file stream in binary format.
74 *
75 * @param file Output file stream
76 * @throws IOException if an I/O error occurs writing to the DataOutputStream.
77 */
78 @Override
79 public void dump(final DataOutputStream file) throws IOException {
80 file.writeByte(super.getTag());
81 file.writeShort(nameIndex);
82 }
83
84 /**
85 * @return dereferenced string
86 */
87 public String getBytes(final ConstantPool cp) {
88 return (String) getConstantValue(cp);
89 }
90
91 /**
92 * @return String object
93 */
94 @Override
95 public Object getConstantValue(final ConstantPool cp) {
96 return cp.getConstantUtf8(nameIndex).getBytes();
97 }
98
99 /**
100 * @return Name index in constant pool of class name.
101 */
102 public int getNameIndex() {
103 return nameIndex;
104 }
105
106 /**
107 * @param nameIndex the name index in the constant pool of this Constant Class
108 */
109 public void setNameIndex(final int nameIndex) {
110 this.nameIndex = nameIndex;
111 }
112
113 /**
114 * @return String representation.
115 */
116 @Override
117 public String toString() {
118 return super.toString() + "(nameIndex = " + nameIndex + ")";
119 }
120 }