Returns the array containing the data, or null if there is no data. The returned array is of the type returned by getDataType() (e.g., for TYPE_INT, it is a int[]).

       <p>Each implementing class should provide a type specific equivalent
       method (e.g., <tt>getDataInt()</tt> in <tt>DataBlkInt</tt>) which
       returns an array of the correct type explicetely and not through an
       <tt>Object</tt>.</p>