How to deal with "oid" field when it contains NULL ?

Hi,

I am retrieving value of "oid" field using "getBlob(columnName)" method
of ResultSet .
It is working fine if that field contains some "oid" reference . But if the
field contains
NULL , then it is throwing following error .

"FastPath call returned ERROR: inv_open: large object 0 not found"

I am able to solve the problem using the following way .

ResultSet rs ;
//If the value of reference is 0 , then there is no Blob value in the
row for the column "columnX".
if(rs.getInt("columnX") != 0){
Blob someBlob = rs.getBlob("columnX");
}

Is there any better way than this ?
Thanks in advance.

Regards,
Ravi