BitSet.hashCode()'s slightly bizarre specification can be made more normal
by using the new public toLongArray method.


     /**
-     * Returns a hash code value for this bit set. The hash code
-     * depends only on which bits have been set within this
-     * {@code BitSet}. The algorithm used to compute it may
-     * be described as follows.
-     *
-     * <p>Suppose the bits in the {@code BitSet} were to be stored
-     * in an array of {@code long} integers called, say,
-     * {@code words}, in such a manner that bit {@code k} is
-     * set in the {@code BitSet} (for nonnegative values of
-     * {@code k}) if and only if the expression
-     * <pre>{@code ((k>>6) < words.length) && ((words[k>>6] & (1L << (bit & 0x3F))) != 0)}</pre>
-     * is true. Then the following definition of the {@code hashCode}
-     * method would be a correct implementation of the actual algorithm:
+     * Returns the hash code value for this bit set. The hash code depends
+     * only on which bits are set within this {@code BitSet}.
+     *
+     * <p>The hash code is defined to be the result of the following
+     * calculation:
      *  <pre> {@code
      * public int hashCode() {
      *      long h = 1234;
-     *      for (int i = words.length; --i >= 0; ) {
+     *     long[] words = toLongArray();
+     *     for (int i = words.length; --i >= 0; )
      *           h ^= words[i] * (i + 1);
-     *      }
      *      return (int)((h >> 32) ^ h);
      * }}</pre>
-     * Note that the hash code values change if the set of bits is altered.
+     * Note that the hash code changes if the set of bits is altered.
      *
-     * @return a hash code value for this bit set
+     * @return the hash code value for this bit set
      */
     public int hashCode() {
Posted Date : 2007-07-29 22:01:44.0

BitSet.hashCode()'s slightly bizarre specification can be made more normal
by using the new public toLongArray method.


     /**
-     * Returns a hash code value for this bit set. The hash code
-     * depends only on which bits have been set within this
-     * {@code BitSet}. The algorithm used to compute it may
-     * be described as follows.
-     *
-     * <p>Suppose the bits in the {@code BitSet} were to be stored
-     * in an array of {@code long} integers called, say,
-     * {@code words}, in such a manner that bit {@code k} is
-     * set in the {@code BitSet} (for nonnegative values of
-     * {@code k}) if and only if the expression
-     * <pre>{@code ((k>>6) < words.length) && ((words[k>>6] & (1L << (bit & 0x3F))) != 0)}</pre>
-     * is true. Then the following definition of the {@code hashCode}
-     * method would be a correct implementation of the actual algorithm:
+     * Returns the hash code value for this bit set. The hash code depends
+     * only on which bits are set within this {@code BitSet}.
+     *
+     * <p>The hash code is defined to be the result of the following
+     * calculation:
      *  <pre> {@code
      * public int hashCode() {
      *      long h = 1234;
-     *      for (int i = words.length; --i >= 0; ) {
+     *     long[] words = toLongArray();
+     *     for (int i = words.length; --i >= 0; )
      *           h ^= words[i] * (i + 1);
-     *      }
      *      return (int)((h >> 32) ^ h);
      * }}</pre>
-     * Note that the hash code values change if the set of bits is altered.
+     * Note that the hash code changes if the set of bits is altered.
      *
-     * @return a hash code value for this bit set
+     * @return the hash code value for this bit set
      */
     public int hashCode() {
Posted Date : 2007-07-29 22:01:44.0

N/A

A fine idea.
Posted Date : 2007-07-29 22:01:44.0