Overriding the Object.finalize method is not a reliable way to terminate use of resources. In particular, there are no guarantees regarding the timeliness of finalizer execution.

Provide explicit termination methods, which should be called by users of an API.

J. Bloch, Effective Java (second edition), Item 7. Addison-Wesley, 2008.

Java Language Specification: 12.6. Finalization of Class Instances.