[postgis-devel] [PostGIS] #193: PGgeometry.hashCode() does not satisfy certain requirements that are standard in Java

[PostGIS]

#193: PGgeometry.hashCode() does not satisfy certain requirements that are
standard in Java
-------------------------+--------------------------------------------------
  Reporter:  danpodeanu  |       Owner:  pramsey      
      Type:  defect      |      Status:  new          
  Priority:  medium      |   Milestone:  PostGIS 1.4.2
 Component:  postgis     |     Version:  1.3.X        
Resolution:              |    Keywords:               
-------------------------+--------------------------------------------------
Comment (by pramsey):

 Possibly helpful information from Martin Davis on the JTS list:
 {{{
  /**
  * Gets a hashcode for this object.
  *
  * @return a hashcode for this object
  */
  public int hashCode() {
   long bits0 = java.lang.Double.doubleToLongBits(p0.x);
   bits0 ^= java.lang.Double.doubleToLongBits(p0.y) * 31;
   int hash0 = (((int) bits0) ^ ((int) (bits0  >> 32)));
     long bits1 = java.lang.Double.doubleToLongBits(p1.x);
   bits1 ^= java.lang.Double.doubleToLongBits(p1.y) * 31;
   int hash1 = (((int) bits1) ^ ((int) (bits1  >> 32)));

   // XOR is supposed to be a good way to combine hashcodes
   return hash0 ^ hash1;
  }
 }}}

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/193#comment:4>
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