ArrayObject


1   package dynaop.util;
2   
3   import java.lang.reflect.Array  ;
4   import java.util.Iterator  ;
5   
6   /**
7    * Implements <code>hashCode()</code> and <code>equals()</code>
8    * functionality for an array. Useful when keying a <code>Map</code> 
9    * with arrays, comparing two arrays for equality, or implementing toString()
10   * for an array. 
11   *
12   * <p>Does not make a defensive copy; behavior
13   * changes with associated array. Does not account for circularly
14   * linked arrays.
15   *
16   * @author Bob Lee (crazybob@crazybob.org)
17   */
18  public class ArrayObject {
19      
20      private final Object   array;
21      
22      /**
23       * Constructs a object for a given array.
24       */
25      public ArrayObject(Object   array) {
26          if (array == null) throw new NullPointerException  ();
27          this.array = array;
28      }
29  
30      public int hashCode() {
31          int hashCode = 0;
32          for (Iterator   i = this.iterator(); i.hasNext();) {
33              Object   element = i.next();
34              if (element != null)
35                  hashCode = hashCode * 37 + element.hashCode();
36          }
37          return hashCode;
38      }
39  
40      public boolean equals(Object   o) {
41          if (o == this) return true;
42          if (!(o instanceof ArrayObject)) return false;
43          ArrayObject arrayObject = (ArrayObject) o;
44          if (this.length() != arrayObject.length()) return false;
45          Iterator   i1 = this.iterator();
46          Iterator   i2 = arrayObject.iterator();
47          while (i1.hasNext()) {
48              Object   o1 = i1.next();
49              Object   o2 = i2.next();
50              if (!(o1==null ? o2==null : o1.equals(o2)))
51                  return false;
52          }
53          return true;
54      }
55  
56      public String   toString() {
57          StringBuffer   buffer = new StringBuffer  ();
58          buffer.append('[');
59          for (Iterator   i = this.iterator(); i.hasNext();) {
60              buffer.append(i.next());
61              if (i.hasNext()) buffer.append(", ");
62          }
63          buffer.append(']');
64          return buffer.toString();
65      }
66      
67      /**
68       * Constructs element iterator. Recursively wraps nested arrays.
69       */
70      private Iterator   iterator() {
71          final int length = this.length();
72          return new Iterator  () {
73  
74              private int index = 0;
75  
76              public boolean hasNext() {
77                  return index < length;
78              }
79  
80              public Object   next() {
81                  Object   element = Array.get(ArrayObject.this.array, index++);
82                  return (element == null) ? null :
83                         (element.getClass().isArray()) ? 
84                              new ArrayObject(element) : element;
85              }
86  
87              public void remove() {
88                  throw new UnsupportedOperationException  ();
89              }
90  
91          };
92      }
93  
94      /** 
95       * Gets length of enclosed array. 
96       */
97      private int length() {
98          return Array.getLength(this.array);
99      }
100     
101     /**
102      * Creates a defensive copy of an array.
103      */
104     public static Object   clone(Object   array) {
105         int length = Array.getLength(array);
106         Object   copy = Array.newInstance(array.getClass().getComponentType(), 
107                 length);
108         System.arraycopy(array, 0, copy, 0, length);
109         return copy;
110     }
111 }
112
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags