Depends on what 'database interface module' is supposed to mean.

It could mean that the algorithm has to store it's data in a database.
This could be because the data is too large for memory of because you
want to keep data from run to run to provide a history.

In that case, you could
- design a database schema and write JDBC code to store and load the data
- use a object-relational mapper (Hibernate is getting good reviews)
- use a Java object database
- hire someone who knows enough about the topic to make the right choice

Or 'database interface module' could mean that you should be able to
present the results of the algorithm such that other database tools
using JDBC could use the data.

In that case you could
- write a JDBC driver that accesses you data structures
- store the result data in a database. This is similar to the options
above, but designing the database schema is more important as it is now
an external interface that has to be documented and reasonable stable.

Daniel