how to declare a lambda expression outside jdbcTemplate.query function?

Question

I have a below code snippet (taken from Mykong tutorial: Spring Boot JDBC Examples):

public class JdbcBookRepository implements BookRepository {

    @Autowired
    private JdbcTemplate jdbcTemplate;

    @Override
    public List<Book> findAll() {
        return jdbcTemplate.query(
                "select * from books",
                (rs, rowNum) ->
                        new Book(
                                rs.getLong("id"),
                                rs.getString("name"),
                                rs.getBigDecimal("price")
                        )
        );
    }

    @Override
    public List<Book> findByNameAndPrice(String name, BigDecimal price) {
        return jdbcTemplate.query(
                "select * from books where name like ? and price <= ?",
                new Object[]{"%" + name + "%", price},
                (rs, rowNum) ->
                        new Book(
                                rs.getLong("id"),
                                rs.getString("name"),
                                rs.getBigDecimal("price")
                        )
        );
    }
}

You can see the duplicate code here:

(rs, rowNum) ->
        new Book(
                rs.getLong("id"),
                rs.getString("name"),
                rs.getBigDecimal("price")
        )

---

In order to remove duplication, I am trying to refactor this code and declare the below function using functional style - like below:

BiFunction<ResultSet,Integer,Book> rowExtractor = (rs, rowNum) ->
        new Book(
                rs.getLong("id"),
                rs.getString("name"),
                rs.getBigDecimal("price")
        );

but Java compiler complains: java: unreported exception java.sql.SQLException; must be caught or declared to be thrown

My question: Is it possible to somehow do it elegantly in java using functional style ?

I know that I can do it "old way" like below, but I wanted to try functional interfaces:

RowMapper<Book> extractor1 = new RowMapper<>(){
   @Override
    public Object mapRow(ResultSet rs, int i) throws SQLException {
        return new Book(
                rs.getLong("id"),
                rs.getString("name"),
                rs.getBigDecimal("price")
        );
    }
}; 

Answer 1

Create a RowMapper as below,

RowMapper<Book> bookRowMapper = (rs, rowNum) ->
                new Book(
                        rs.getLong("id"),
                        rs.getString("name"),
                        rs.getBigDecimal("price")
                );

And use as below,

jdbcTemplate.query("select * from books", bookRowMapper);

jdbcTemplate.query(
        "select * from books where name like ? and price <= ?",
        new Object[]{"%" + name + "%", price},
        bookRowMapper
);