NoOverwriteMap


1   /*
2    * $Id: NoOverwriteMap.java,v 1.1 2002/01/03 00:51:06 lhoriman Exp $
3    * $Source: /cvsroot/mav/maverick/src/java/org/infohazard/maverick/util/NoOverwriteMap.java,v $
4    */
5   
6   package org.infohazard.maverick.util;
7   
8   import java.util.Map  ;
9   import java.util.Set  ;
10  import java.util.Collection  ;
11  import java.util.Iterator  ;
12  
13  /**
14   * Map wrapper which prevents overwriting existing keys.
15   */
16  public class NoOverwriteMap implements Map  
17  {
18      /**
19       */
20      public static class OverwriteException extends IllegalArgumentException  
21      {
22          /** */
23          protected Object   key;
24  
25          /** */
26          public OverwriteException(Object   key)
27          {
28              super("Tried to overwrite key:  " + key);
29  
30              this.key = key;
31          }
32  
33          /** */
34          public Object   getDuplicateKey()
35          {
36              return this.key;
37          }
38      }
39  
40      /**
41       */
42      protected Map   wrapped;
43  
44      /**
45       */
46      public NoOverwriteMap(Map   wrap)
47      {
48          this.wrapped = wrap;
49      }
50  
51      /**
52       */
53      public int size()                   { return wrapped.size(); }
54      public boolean isEmpty()            { return wrapped.isEmpty(); }
55      public boolean containsKey(Object   key)      { return wrapped.containsKey(key); }
56      public boolean containsValue(Object   value)  { return wrapped.containsValue(value); }
57      public Object   get(Object   key)       { return wrapped.get(key); }
58      public Object   remove(Object   key)    { return wrapped.remove(key); }
59      public void clear()                 { wrapped.clear(); }
60      public Set   keySet()                 { return wrapped.keySet(); }
61      public Collection   values()          { return wrapped.values(); }
62      public Set   entrySet()               { return wrapped.entrySet(); }
63      public boolean equals(Object   o)     { return wrapped.equals(o); }
64      public int hashCode()               { return wrapped.hashCode(); }
65  
66      /**
67       * Prevents overwriting existing keys.
68       * @throws OverwriteException if the key is already present.
69       */
70      public Object   put(Object   key, Object   value)
71      {
72          if (this.containsKey(key))
73              throw new OverwriteException(key);
74  
75          return this.wrapped.put(key, value);
76      }
77  
78      /**
79       * Prevents overwriting existing keys.
80       * @throws OverwriteException if the key is already present.
81       */
82      public void putAll(Map   t)
83      {
84          Iterator   it = t.entrySet().iterator();
85  
86          while (it.hasNext())
87          {
88              Map.Entry   entry = (Map.Entry  )it.next();
89              this.put(entry.getKey(), entry.getValue());
90          }
91      }
92  }
93
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