private void checkCursor() throws SQLException {
        if (isAfterLast() == true || isBeforeFirst() == true) {
            throw new SQLException(resBundle.handleGetObject("cachedrowsetimpl.invalidcp").toString());
        }
    }
Checks to see whether the cursor for this <code>CachedRowSetImpl</code>
object is on a row in the rowset and throws an
<code>SQLException</code> if it is not.
<P>
This method is called internally by <code>getXXX</code> methods, by
<code>updateXXX</code> methods, and by methods that update, insert,
or delete a row or that cancel a row update, insert, or delete.

@throws SQLException if the cursor for this <code>CachedRowSetImpl</code>
        object is not on a valid row
src/main/java/org/replicadb/rowset/sun/rowset/CachedRowSetImpl.java