Variable


1   /*
2    * Variable.java
3    *
4    * The contents of this file are subject to the terms of the Common Development
5    * and Distribution License (the License). You may not use this file except in
6    * compliance with the License.
7    *
8    * You can obtain a copy of the License at http://www.netbeans.org/cddl.html
9    * or http://www.netbeans.org/cddl.txt.
10   *
11   * When distributing Covered Code, include this CDDL Header Notice in each file
12   * and include the License file at http://www.netbeans.org/cddl.txt.
13   * If applicable, add the following below the CDDL Header, with the fields
14   * enclosed by brackets [] replaced by your own identifying information:
15   * "Portions Copyrighted [year] [name of copyright owner]"
16   *
17   * The Original Software is NetBeans. The Initial Developer of the Original
18   * Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun
19   * Microsystems, Inc. All Rights Reserved.
20   *
21   * Contributor(s): Thomas Ball
22   *
23   * Version: $Revision: 1.10 $
24   */
25  
26  package org.netbeans.modules.classfile;
27  
28  import java.io.*;
29  
30  /**
31   * A Java field.  Unfortunately, the word "field" is generally used in
32   * the Java documentation to mean either a variable, or both variables
33   * and methods.  This class only describes variables.
34   *
35   * @author  Thomas Ball
36   */
37  public final class Variable extends Field {
38  
39      private Object   constValue = notLoadedConstValue;
40      
41      private static final Object   notLoadedConstValue = new Object  ();
42  
43      static Variable[] loadFields(DataInputStream in, ConstantPool pool,
44                                   ClassFile cls) 
45        throws IOException {
46            int count = in.readUnsignedShort();
47            Variable[] variables = new Variable[count];
48            for (int i = 0; i < count; i++)
49                variables[i] = new Variable(in, pool, cls);
50            return variables;
51      }
52      
53      /** Creates new Variable */
54      Variable(DataInputStream in, ConstantPool pool, ClassFile cls) 
55      throws IOException {
56          super(in, pool, cls, false);
57      }
58  
59      /**
60       * Returns true if the variable is a constant; that is, a final
61       * static variable.
62       * @see #getConstantValue
63       */
64      public final boolean isConstant() {
65          return attributes.get("ConstantValue") != null;//NOI18N
66      }
67  
68      /**
69       * Returns the value object of this variable if it is a constant,
70       * otherwise null.
71       * @deprecated replaced by <code>Object getConstantValue()</code>.
72       */
73      @Deprecated  
74      public final Object   getValue() {
75      return getConstantValue();
76      }
77      
78      /**
79       * Returns the value object of this variable if it is a constant,
80       * otherwise null.
81       * @see #isConstant
82       */
83      public final Object   getConstantValue() {
84      if (constValue == notLoadedConstValue) {
85          DataInputStream in = attributes.getStream("ConstantValue"); // NOI18N
86          if (in != null) {
87          try {
88              int index = in.readUnsignedShort();
89              CPEntry cpe = classFile.constantPool.get(index);
90              constValue = cpe.getValue();
91          } catch (IOException e) {
92              throw new InvalidClassFileAttributeException("invalid ConstantValue attribute", e);
93          }
94          }
95      }
96          return constValue;
97      }
98      
99      /**
100      * Return a string in the form "<type> <name>".  Class types
101      * are shown in a "short" form; i.e. "Object" instead of
102      * "java.lang.Object"j.
103      *
104      * @return string describing the variable and its type.
105      */
106     public final String   getDeclaration() {
107     StringBuffer   sb = new StringBuffer  ();
108     sb.append(CPFieldMethodInfo.getSignature(getDescriptor(), false));
109     sb.append(' ');
110     sb.append(getName());
111     return sb.toString();
112     }
113 
114     /**
115      * Returns true if this field defines an enum constant.
116      */
117     public final boolean isEnumConstant() {
118     return (access & Access.ENUM) == Access.ENUM;
119     }
120             
121     public String   toString() {
122         StringBuffer   sb = new StringBuffer  (super.toString());
123         if (isConstant()) {
124         sb.append(", const value="); //NOI18N
125         sb.append(getValue());
126     }
127         return sb.toString();
128     }
129 }
130
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