Hi,
FBResultSet has still an open bug:

public boolean getBoolean(int columnIndex) throws SQLException {
Object obj = getObject(columnIndex).toString();

should be substituted with

public boolean getBoolean(int columnIndex) throws SQLException {
Object obj = getObject(columnIndex);

else the following statements will not work.
(if (obj == null) and if (obj instanceof Number))

Regards
Massimo