Debabrat Nayak

You don't have to hard code the absolute path of the hibernate.cfg.xml. You can access it by relative path. Assuming your hibernate.cfg.xml is in src folder under com/hibernateweb/config/hibernate.cfg.xml, you can do the following:

URL url = Thread.currentThread().getContextClassLoader().getResource("com/hibernateweb/config/hibernate.cfg.xml");
SessionFactory sessionFactory = new Configuration().configure(url).buildSessionFactory();
session = sessionFactory.openSession();

You can have your applet signed by CA. If the applet can be verified then, this security warning will not show up.

Paul,
Garbage collection is a lower priority activity for the JVM. Hence, even if you invoke System.gc(), it doesn't guarantee garbage collection instantly. You can configure JVM parameters to do more efficient garbage collection. Please note that too frequent GC is also not good as it will result in higher resource usage (like CPU) and can inversely affect the performance.