NameGenerator


1   /*
2    * @(#)NameGenerator.java   1.9 03/12/19
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   package java.beans;
8   
9   import java.util.HashMap  ;
10  import java.util.IdentityHashMap  ;
11  import java.util.Map  ;
12  
13  /**
14   * A utility class which generates unique names for object instances.
15   * The name will be a concatenation of the unqualified class name 
16   * and an instance number.
17   * <p>
18   * For example, if the first object instance javax.swing.JButton 
19   * is passed into <code>instanceName</code> then the returned
20   * string identifier will be &quot;JButton0&quot;.
21   * 
22   * @version 1.9 12/19/03
23   * @author Philip Milne
24   */
25  class NameGenerator { 
26  
27      private Map   valueToName; 
28      private Map   nameToCount;
29      
30      public NameGenerator() {
31          valueToName = new IdentityHashMap  ();
32          nameToCount = new HashMap  ();
33      }
34      
35      /**
36       * Clears the name cache. Should be called to near the end of
37       * the encoding cycle.
38       */
39      public void clear() { 
40      valueToName.clear();
41      nameToCount.clear();
42      }
43      
44      /**
45       * Returns the root name of the class.
46       */
47      public static String   unqualifiedClassName(Class   type) { 
48          if (type.isArray()) {
49              return unqualifiedClassName(type.getComponentType())+"Array"; 
50          }
51          String   name = type.getName(); 
52          return name.substring(name.lastIndexOf('.')+1); 
53      }
54  
55      /**
56       * Returns a String which capitalizes the first letter of the string.
57       */
58      public static String   capitalize(String   name) { 
59      if (name == null || name.length() == 0) { 
60          return name; 
61          }
62      return name.substring(0, 1).toUpperCase() + name.substring(1);
63      }
64      
65      /**
66       * Returns a unique string which identifies the object instance.
67       * Invocations are cached so that if an object has been previously
68       * passed into this method then the same identifier is returned.
69       * 
70       * @param instance object used to generate string
71       * @return a unique string representing the object
72       */
73      public String   instanceName(Object   instance) {         
74          if (instance == null) {
75              return "null"; 
76          }
77          if (instance instanceof Class  ) {
78              return unqualifiedClassName((Class  )instance); 
79          }
80          else { 
81              String   result = (String  )valueToName.get(instance); 
82              if (result != null) { 
83                  return result; 
84              }
85              Class   type = instance.getClass(); 
86              String   className = unqualifiedClassName(type); 
87  
88              Object   size = nameToCount.get(className); 
89              int instanceNumber = (size == null) ? 0 : ((Integer  )size).intValue() + 1; 
90              nameToCount.put(className, new Integer  (instanceNumber)); 
91  
92              result = className + instanceNumber; 
93              valueToName.put(instance, result); 
94              return result; 
95          }
96      }
97  }
98
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