code: public Double asDoubleObj() {
  		if (current == null)
  			return null;
  		if (current instanceof Number) {
  			if (current instanceof Double)
  				return (Double) current;
  			return Double.valueOf(((Number) current).doubleValue());
  		}
  		return Double.NaN;
  	}
docs: get the current object value as Double if the current Double can not be
  cast as Integer return null.