Is closing the connection in finalize best practice? [duplicate]

Question

Possible Duplicate:
Why would you ever implement finalize()?

I saw some java files with the following code:

public void finalize() {
    if (conn != null) {
        try {
            conn.close();
        } catch (SQLException e) {
        }
    }
}

• Is closing a Connection in the finalize method best practice?
• Is it enough to close the Connection or does one need to also close other objects such as PreparedStatement?

Answer 1

From Java 7, the best practice for closing a resource is to use a try-with-resource :

http://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html

Answer 2

No, that is not "best practice", or even "passable practice". You have no guarantee when if at all finalizers are called, so it won't work.

Instead you should scope out resources to a block, like this:

try {
  acquire resource
}
finally {
  if (resource was acquired)
    release it
}

Answer 3

No, the finalizer is unlikely to be called in a timely manner, if ever. Clean up your resources explicitly and certainly.

/* Acquire resource. */
try {
  /* Use resource. */
}
finally {
  /* Release resource. */
}