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17 package org.apache.bcel.classfile;
18
19 import java.io.DataInputStream;
20 import java.io.IOException;
21 import org.apache.bcel.Constants;
22 import org.apache.bcel.generic.Type;
23 import org.apache.bcel.util.BCELComparator;
24
25 /***
26 * This class represents the field info structure, i.e., the representation
27 * for a variable in the class. See JVM specification for details.
28 *
29 * @version $Id: Field.java 386056 2006-03-15 11:31:56Z tcurdt $
30 * @author <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
31 */
32 public final class Field extends FieldOrMethod {
33
34 private static BCELComparator _cmp = new BCELComparator() {
35
36 public boolean equals( Object o1, Object o2 ) {
37 Field THIS = (Field) o1;
38 Field THAT = (Field) o2;
39 return THIS.getName().equals(THAT.getName())
40 && THIS.getSignature().equals(THAT.getSignature());
41 }
42
43
44 public int hashCode( Object o ) {
45 Field THIS = (Field) o;
46 return THIS.getSignature().hashCode() ^ THIS.getName().hashCode();
47 }
48 };
49
50
51 /***
52 * Initialize from another object. Note that both objects use the same
53 * references (shallow copy). Use clone() for a physical copy.
54 */
55 public Field(Field c) {
56 super(c);
57 }
58
59
60 /***
61 * Construct object from file stream.
62 * @param file Input stream
63 */
64 Field(DataInputStream file, ConstantPool constant_pool) throws IOException,
65 ClassFormatException {
66 super(file, constant_pool);
67 }
68
69
70 /***
71 * @param access_flags Access rights of field
72 * @param name_index Points to field name in constant pool
73 * @param signature_index Points to encoded signature
74 * @param attributes Collection of attributes
75 * @param constant_pool Array of constants
76 */
77 public Field(int access_flags, int name_index, int signature_index, Attribute[] attributes,
78 ConstantPool constant_pool) {
79 super(access_flags, name_index, signature_index, attributes, constant_pool);
80 }
81
82
83 /***
84 * Called by objects that are traversing the nodes of the tree implicitely
85 * defined by the contents of a Java class. I.e., the hierarchy of methods,
86 * fields, attributes, etc. spawns a tree of objects.
87 *
88 * @param v Visitor object
89 */
90 public void accept( Visitor v ) {
91 v.visitField(this);
92 }
93
94
95 /***
96 * @return constant value associated with this field (may be null)
97 */
98 public final ConstantValue getConstantValue() {
99 for (int i = 0; i < attributes_count; i++) {
100 if (attributes[i].getTag() == Constants.ATTR_CONSTANT_VALUE) {
101 return (ConstantValue) attributes[i];
102 }
103 }
104 return null;
105 }
106
107
108 /***
109 * Return string representation close to declaration format,
110 * `public static final short MAX = 100', e.g..
111 *
112 * @return String representation of field, including the signature.
113 */
114 public final String toString() {
115 String name, signature, access;
116
117 access = Utility.accessToString(access_flags);
118 access = access.equals("") ? "" : (access + " ");
119 signature = Utility.signatureToString(getSignature());
120 name = getName();
121 StringBuffer buf = new StringBuffer(64);
122 buf.append(access).append(signature).append(" ").append(name);
123 ConstantValue cv = getConstantValue();
124 if (cv != null) {
125 buf.append(" = ").append(cv);
126 }
127 for (int i = 0; i < attributes_count; i++) {
128 Attribute a = attributes[i];
129 if (!(a instanceof ConstantValue)) {
130 buf.append(" [").append(a.toString()).append("]");
131 }
132 }
133 return buf.toString();
134 }
135
136
137 /***
138 * @return deep copy of this field
139 */
140 public final Field copy( ConstantPool _constant_pool ) {
141 return (Field) copy_(_constant_pool);
142 }
143
144
145 /***
146 * @return type of field
147 */
148 public Type getType() {
149 return Type.getReturnType(getSignature());
150 }
151
152
153 /***
154 * @return Comparison strategy object
155 */
156 public static BCELComparator getComparator() {
157 return _cmp;
158 }
159
160
161 /***
162 * @param comparator Comparison strategy object
163 */
164 public static void setComparator( BCELComparator comparator ) {
165 _cmp = comparator;
166 }
167
168
169 /***
170 * Return value as defined by given BCELComparator strategy.
171 * By default two Field objects are said to be equal when
172 * their names and signatures are equal.
173 *
174 * @see java.lang.Object#equals(java.lang.Object)
175 */
176 public boolean equals( Object obj ) {
177 return _cmp.equals(this, obj);
178 }
179
180
181 /***
182 * Return value as defined by given BCELComparator strategy.
183 * By default return the hashcode of the field's name XOR signature.
184 *
185 * @see java.lang.Object#hashCode()
186 */
187 public int hashCode() {
188 return _cmp.hashCode(this);
189 }
190 }