Closing all existing PostgreSQL database connections

Hi,

I've got a question about PostgreSQL JDBC API. Is there any way to
close all existing & open connections to the particular database. I
mean the connections made by some external programs too.

I simply need to drop the database to which there are some open
external connections. I cannot get the java.sql.Connection object in
order to close the connection, but maybe there is some other way to do
this?

Regards, Norbert