1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * https://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.apache.bcel.classfile;
20
21 import java.io.DataInput;
22 import java.io.DataOutputStream;
23 import java.io.IOException;
24
25 import org.apache.bcel.Const;
26
27 /**
28 * This class is derived from the abstract {@link Constant} and represents a reference to a (external) class.
29 *
30 * @see Constant
31 */
32 public final class ConstantClass extends Constant implements ConstantObject {
33
34 private int nameIndex; // Identical to ConstantString except for the name
35
36 /**
37 * Initialize from another object.
38 *
39 * @param c Source to copy.
40 */
41 public ConstantClass(final ConstantClass c) {
42 this(c.getNameIndex());
43 }
44
45 /**
46 * Constructs an instance from file data.
47 *
48 * @param dataInput Input stream
49 * @throws IOException if an I/O error occurs reading from the given {@code dataInput}.
50 */
51 ConstantClass(final DataInput dataInput) throws IOException {
52 this(dataInput.readUnsignedShort());
53 }
54
55 /**
56 * @param nameIndex Name index in constant pool. Should refer to a ConstantUtf8.
57 */
58 public ConstantClass(final int nameIndex) {
59 super(Const.CONSTANT_Class);
60 this.nameIndex = nameIndex;
61 }
62
63 /**
64 * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
65 * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
66 *
67 * @param v Visitor object
68 */
69 @Override
70 public void accept(final Visitor v) {
71 v.visitConstantClass(this);
72 }
73
74 /**
75 * Dumps constant class to file stream in binary format.
76 *
77 * @param file Output file stream
78 * @throws IOException if an I/O error occurs writing to the DataOutputStream.
79 */
80 @Override
81 public void dump(final DataOutputStream file) throws IOException {
82 file.writeByte(super.getTag());
83 file.writeShort(nameIndex);
84 }
85
86 /**
87 * @return dereferenced string
88 */
89 public String getBytes(final ConstantPool cp) {
90 return (String) getConstantValue(cp);
91 }
92
93 /**
94 * @return String object
95 */
96 @Override
97 public Object getConstantValue(final ConstantPool cp) {
98 return cp.getConstantUtf8(nameIndex).getBytes();
99 }
100
101 /**
102 * @return Name index in constant pool of class name.
103 */
104 public int getNameIndex() {
105 return nameIndex;
106 }
107
108 /**
109 * @param nameIndex the name index in the constant pool of this Constant Class
110 */
111 public void setNameIndex(final int nameIndex) {
112 this.nameIndex = nameIndex;
113 }
114
115 /**
116 * @return String representation.
117 */
118 @Override
119 public String toString() {
120 return super.toString() + "(nameIndex = " + nameIndex + ")";
121 }
122 }