Re: Returning A ResultSet

From:

Tom Hawtin <usenet@tackline.plus.com>

Newsgroups:

comp.lang.java.programmer

Date:

Wed, 11 Apr 2007 22:42:25 +0100

Message-ID:

<461d55aa$0$8721$ed2619ec@ptn-nntp-reader02.plus.net>

ast3r3x@gmail.com wrote:

Then when I actually use that, I just do the following. I think when I
do db = null that my override of finalize should run in my class, and
then all the variables/connections will be closed/deallocated properly
correct?

No. The finalize method is not called deterministically. This makes it
pretty useless.

As an example of Execute Around, you want your code looking like:

     executeQuery(someStatement, new ResultSetHandler() {
             public void handle(ResultSet results) throws SQLException {
                 ... do stuff with results ....
             }
     });

Where ResultSetHandler is a simple interface.

public interface ResultSetHandler {
     void handle(ResultSet results) throws SQLException;
}

And executeQueue is just a static method with the boilerplate. Close you
resources, wrap thrown exceptions, iterate over rows - do whatever you
like. I'll just close the result set.

     static void executeQuery(
         PreparedStatement statement, ResultSetHandler handler
     ) throws SQLException {
         ResultSet results = statement.executeQuery();
         try {
             handler.handle(results);
         } finally {
             results.close();
         }
     }

(Disclaimer: Not so much as compiled this code.)

Tom Hawtin