Modifier


1   /*
2    * @(#)Modifier.java    1.27 04/02/17
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   
8   package java.lang.reflect;
9   
10  import java.security.AccessController  ;
11  import sun.reflect.LangReflectAccess;
12  import sun.reflect.ReflectionFactory;
13  
14  /**
15   * The Modifier class provides <code>static</code> methods and
16   * constants to decode class and member access modifiers.  The sets of
17   * modifiers are represented as integers with distinct bit positions
18   * representing different modifiers.  The values for the constants
19   * representing the modifiers are taken from <a
20   * HREF="http://java.sun.com/docs/books/vmspec/2nd-edition/html/VMSpecTOC.doc.html"><i>The
21   * Java</i><sup><small>TM</small></sup> <i>Virtual Machine Specification, Second
22   * edition</i></a> tables 
23   * <a HREF="http://java.sun.com/docs/books/vmspec/2nd-edition/html/ClassFile.doc.html#75734">4.1</a>,
24   * <a HREF="http://java.sun.com/docs/books/vmspec/2nd-edition/html/ClassFile.doc.html#88358">4.4</a>,
25   * <a HREF="http://java.sun.com/docs/books/vmspec/2nd-edition/html/ClassFile.doc.html#75568">4.5</a>, and 
26   * <a HREF="http://java.sun.com/docs/books/vmspec/2nd-edition/html/ClassFile.doc.html#88478">4.7</a>.
27   *
28   * @see Class#getModifiers()
29   * @see Member#getModifiers()
30   *
31   * @author Nakul Saraiya
32   * @author Kenneth Russell
33   */
34  public
35  class Modifier {
36  
37      /* 
38       * Bootstrapping protocol between java.lang and java.lang.reflect
39       *  packages 
40       */
41      static {
42          sun.reflect.ReflectionFactory factory =
43              (sun.reflect.ReflectionFactory) AccessController.doPrivileged(
44                  new ReflectionFactory.GetReflectionFactoryAction()
45              );
46          factory.setLangReflectAccess(new java.lang.reflect.ReflectAccess  ());
47      }
48  
49      /**
50       * Return <tt>true</tt> if the integer argument includes the
51       * <tt>public</tt> modifier, <tt>false</tt> otherwise.
52       *
53       * @param   mod a set of modifiers
54       * @return <tt>true</tt> if <code>mod</code> includes the
55       * <tt>public</tt> modifier; <tt>false</tt> otherwise.
56       */
57      public static boolean isPublic(int mod) {
58      return (mod & PUBLIC) != 0;
59      }
60  
61      /**
62       * Return <tt>true</tt> if the integer argument includes the
63       * <tt>private</tt> modifier, <tt>false</tt> otherwise.
64       *
65       * @param   mod a set of modifiers
66       * @return <tt>true</tt> if <code>mod</code> includes the
67       * <tt>private</tt> modifier; <tt>false</tt> otherwise.
68       */
69      public static boolean isPrivate(int mod) {
70      return (mod & PRIVATE) != 0;
71      }
72  
73      /**
74       * Return <tt>true</tt> if the integer argument includes the
75       * <tt>protected</tt> modifier, <tt>false</tt> otherwise.
76       *
77       * @param   mod a set of modifiers
78       * @return <tt>true</tt> if <code>mod</code> includes the
79       * <tt>protected</tt> modifier; <tt>false</tt> otherwise.
80       */
81      public static boolean isProtected(int mod) {
82      return (mod & PROTECTED) != 0;
83      }
84  
85      /**
86       * Return <tt>true</tt> if the integer argument includes the
87       * <tt>static</tt> modifier, <tt>false</tt> otherwise.
88       *
89       * @param   mod a set of modifiers
90       * @return <tt>true</tt> if <code>mod</code> includes the
91       * <tt>static</tt> modifier; <tt>false</tt> otherwise.
92       */
93      public static boolean isStatic(int mod) {
94      return (mod & STATIC) != 0;
95      }
96  
97      /**
98       * Return <tt>true</tt> if the integer argument includes the
99       * <tt>final</tt> modifier, <tt>false</tt> otherwise.
100      *
101      * @param   mod a set of modifiers
102      * @return <tt>true</tt> if <code>mod</code> includes the
103      * <tt>final</tt> modifier; <tt>false</tt> otherwise.
104      */
105     public static boolean isFinal(int mod) {
106     return (mod & FINAL) != 0;
107     }
108 
109     /**
110      * Return <tt>true</tt> if the integer argument includes the
111      * <tt>synchronized</tt> modifier, <tt>false</tt> otherwise.
112      *
113      * @param   mod a set of modifiers
114      * @return <tt>true</tt> if <code>mod</code> includes the
115      * <tt>synchronized</tt> modifier; <tt>false</tt> otherwise.
116      */
117     public static boolean isSynchronized(int mod) {
118     return (mod & SYNCHRONIZED) != 0;
119     }
120 
121     /**
122      * Return <tt>true</tt> if the integer argument includes the
123      * <tt>volatile</tt> modifier, <tt>false</tt> otherwise.
124      *
125      * @param   mod a set of modifiers
126      * @return <tt>true</tt> if <code>mod</code> includes the
127      * <tt>volatile</tt> modifier; <tt>false</tt> otherwise.
128      */
129     public static boolean isVolatile(int mod) {
130     return (mod & VOLATILE) != 0;
131     }
132 
133     /**
134      * Return <tt>true</tt> if the integer argument includes the
135      * <tt>transient</tt> modifier, <tt>false</tt> otherwise.
136      *
137      * @param   mod a set of modifiers
138      * @return <tt>true</tt> if <code>mod</code> includes the
139      * <tt>transient</tt> modifier; <tt>false</tt> otherwise.
140      */
141     public static boolean isTransient(int mod) {
142     return (mod & TRANSIENT) != 0;
143     }
144 
145     /**
146      * Return <tt>true</tt> if the integer argument includes the
147      * <tt>native</tt> modifier, <tt>false</tt> otherwise.
148      *
149      * @param   mod a set of modifiers
150      * @return <tt>true</tt> if <code>mod</code> includes the
151      * <tt>native</tt> modifier; <tt>false</tt> otherwise.
152      */
153     public static boolean isNative(int mod) {
154     return (mod & NATIVE) != 0;
155     }
156 
157     /**
158      * Return <tt>true</tt> if the integer argument includes the
159      * <tt>interface</tt> modifier, <tt>false</tt> otherwise.
160      *
161      * @param   mod a set of modifiers
162      * @return <tt>true</tt> if <code>mod</code> includes the
163      * <tt>interface</tt> modifier; <tt>false</tt> otherwise.
164      */
165     public static boolean isInterface(int mod) {
166     return (mod & INTERFACE) != 0;
167     }
168 
169     /**
170      * Return <tt>true</tt> if the integer argument includes the
171      * <tt>abstract</tt> modifier, <tt>false</tt> otherwise.
172      *
173      * @param   mod a set of modifiers
174      * @return <tt>true</tt> if <code>mod</code> includes the
175      * <tt>abstract</tt> modifier; <tt>false</tt> otherwise.
176      */
177     public static boolean isAbstract(int mod) {
178     return (mod & ABSTRACT) != 0;
179     }
180 
181     /**
182      * Return <tt>true</tt> if the integer argument includes the
183      * <tt>strictfp</tt> modifier, <tt>false</tt> otherwise.
184      *
185      * @param   mod a set of modifiers
186      * @return <tt>true</tt> if <code>mod</code> includes the
187      * <tt>strictfp</tt> modifier; <tt>false</tt> otherwise.
188      */
189     public static boolean isStrict(int mod) {
190     return (mod & STRICT) != 0;
191     }
192 
193     /**
194      * Return a string describing the access modifier flags in
195      * the specified modifier. For example:
196      * <blockquote><pre>
197      *    public final synchronized strictfp
198      * </pre></blockquote>
199      * The modifier names are returned in an order consistent with the
200      * suggested modifier orderings given in <a
201      * HREF="http://java.sun.com/docs/books/jls/second_edition/html/j.title.doc.html"><em>The
202      * Java Language Specification, Second Edition</em></a> sections
203      * <a HREF="http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#21613">&sect;8.1.1</a>, 
204      * <a HREF="http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#78091">&sect;8.3.1</a>, 
205      * <a HREF="http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#78188">&sect;8.4.3</a>, 
206      * <a HREF="http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#42018">&sect;8.8.3</a>, and
207      * <a HREF="http://java.sun.com/docs/books/jls/second_edition/html/interfaces.doc.html#235947">&sect;9.1.1</a>.  
208      * The full modifier ordering used by this method is:
209      * <blockquote> <code> 
210      * public protected private abstract static final transient
211      * volatile synchronized native strictfp
212      * interface </code> </blockquote> 
213      * The <code>interface</code> modifier discussed in this class is
214      * not a true modifier in the Java language and it appears after
215      * all other modifiers listed by this method.  This method may
216      * return a string of modifiers that are not valid modifiers of a
217      * Java entity; in other words, no checking is done on the
218      * possible validity of the combination of modifiers represented
219      * by the input.
220      *
221      * @param   mod a set of modifiers
222      * @return  a string representation of the set of modifiers
223      * represented by <code>mod</code>
224      */
225     public static String   toString(int mod) {
226     StringBuffer   sb = new StringBuffer  ();
227     int len;
228 
229     if ((mod & PUBLIC) != 0)    sb.append("public ");
230     if ((mod & PROTECTED) != 0) sb.append("protected ");
231     if ((mod & PRIVATE) != 0)   sb.append("private ");
232 
233     /* Canonical order */
234     if ((mod & ABSTRACT) != 0)  sb.append("abstract ");
235     if ((mod & STATIC) != 0)    sb.append("static ");
236     if ((mod & FINAL) != 0)     sb.append("final ");
237     if ((mod & TRANSIENT) != 0) sb.append("transient ");
238     if ((mod & VOLATILE) != 0)  sb.append("volatile ");
239     if ((mod & SYNCHRONIZED) != 0)  sb.append("synchronized ");
240     if ((mod & NATIVE) != 0)    sb.append("native ");
241     if ((mod & STRICT) != 0)    sb.append("strictfp ");
242     if ((mod & INTERFACE) != 0) sb.append("interface ");
243 
244     if ((len = sb.length()) > 0)    /* trim trailing space */
245         return sb.toString().substring(0, len-1);
246     return "";
247     }
248 
249     /*
250      * Access modifier flag constants from <em>The Java Virtual
251      * Machine Specification, Second Edition</em>, tables 4.1, 4.4,
252      * 4.5, and 4.7.
253      */
254 
255     /**
256      * The <code>int</code> value representing the <code>public</code> 
257      * modifier.
258      */    
259     public static final int PUBLIC           = 0x00000001;
260 
261     /**
262      * The <code>int</code> value representing the <code>private</code> 
263      * modifier.
264      */    
265     public static final int PRIVATE          = 0x00000002;
266 
267     /**
268      * The <code>int</code> value representing the <code>protected</code> 
269      * modifier.
270      */    
271     public static final int PROTECTED        = 0x00000004;
272 
273     /**
274      * The <code>int</code> value representing the <code>static</code> 
275      * modifier.
276      */    
277     public static final int STATIC           = 0x00000008;
278 
279     /**
280      * The <code>int</code> value representing the <code>final</code> 
281      * modifier.
282      */    
283     public static final int FINAL            = 0x00000010;
284 
285     /**
286      * The <code>int</code> value representing the <code>synchronized</code> 
287      * modifier.
288      */    
289     public static final int SYNCHRONIZED     = 0x00000020;
290 
291     /**
292      * The <code>int</code> value representing the <code>volatile</code> 
293      * modifier.
294      */    
295     public static final int VOLATILE         = 0x00000040;
296 
297     /**
298      * The <code>int</code> value representing the <code>transient</code> 
299      * modifier.
300      */    
301     public static final int TRANSIENT        = 0x00000080;
302 
303     /**
304      * The <code>int</code> value representing the <code>native</code> 
305      * modifier.
306      */    
307     public static final int NATIVE           = 0x00000100;
308 
309     /**
310      * The <code>int</code> value representing the <code>interface</code> 
311      * modifier.
312      */    
313     public static final int INTERFACE        = 0x00000200;
314 
315     /**
316      * The <code>int</code> value representing the <code>abstract</code> 
317      * modifier.
318      */    
319     public static final int ABSTRACT         = 0x00000400;
320 
321     /**
322      * The <code>int</code> value representing the <code>strictfp</code> 
323      * modifier.
324      */    
325     public static final int STRICT           = 0x00000800;
326 
327     // Bits not (yet) exposed in the public API either because they
328     // have different meanings for fields and methods and there is no
329     // way to distinguish between the two in this class, or because
330     // they are not Java programming language keywords
331     static final int BRIDGE    = 0x00000040;
332     static final int VARARGS   = 0x00000080;
333     static final int SYNTHETIC = 0x00001000;
334     static final int ANNOTATION= 0x00002000;
335     static final int ENUM      = 0x00004000;
336     static boolean isSynthetic(int mod) {
337       return (mod & SYNTHETIC) != 0;
338     }
339 }
340
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