code: private static Number neg(Number n) 
    {
      switch (getType(n)) 
      {
        case INT :
          return new Integer(-n.intValue());
        case LONG :
          return new Long(-n.longValue());
        case FLOAT :
          return new Float(-n.floatValue());
        case DOUBLE :
          return new Double(-n.doubleValue());
        default :
          throw new IllegalStateException();
      }
    }
docs: Negate the value