Storing Large Objects: ClassCastException

I'm using Java to write an application that needs the ability to store
and retrieve pdf files from a postgresql database. I'm using the code
from the postgresql docs to store a pdf. At the bottom of this message
is the code I'm using but right here is the line that is producing a
ClassCastException:

LargeObjectManager lobj =
((org.postgresql.PGConnection)conn).getLargeObjectAPI();

I found a post earlier that dealt with this same problem but it wasn't
very helpful. Any help would be appreciated. Thanks in advance.

-----------------------------
To insert an image, you would use:
// All LargeObject API calls must be within a transaction block
conn.setAutoCommit(false);

// Get the Large Object Manager to perform operations with
LargeObjectManager lobj =
((org.postgresql.PGConnection)conn).getLargeObjectAPI();

// Create a new large object
int oid = lobj.create(LargeObjectManager.READ |
LargeObjectManager.WRITE);

// Open the large object for writing
LargeObject obj = lobj.open(oid, LargeObjectManager.WRITE);

// Now open the file
File file = new File("myimage.gif");
FileInputStream fis = new FileInputStream(file);

// Copy the data from the file to the large object
byte buf[] = new byte[2048];
int s, tl = 0;
while ((s = fis.read(buf, 0, 2048)) > 0) {
obj.write(buf, 0, s);
tl += s;
}

// Close the large object
obj.close();

// Now insert the row into imageslo
PreparedStatement ps = conn.prepareStatement("INSERT INTO imageslo
VALUES (?, ?)");
ps.setString(1, file.getName());
ps.setInt(2, oid);
ps.executeUpdate();
ps.close();
fis.close();
-----------------------------

Carter R. Harrison