Question

I’m really new to java, and I need to know is this a memory leak ?

This is a piece of code from a game server I’m trying to improve:

---

private static void closePreparedStatement(PreparedStatement p)
{
    try {
        p.clearParameters();
        p.close();
    } catch (SQLException e) {e.printStackTrace();}
}

---

public static void UPDATE_ACCOUNT(Compte acc)
{
    try
    {
        String baseQuery = "UPDATE accounts SET " +
                            "`bankGold` = ?,"+
                            "`bank` = ?,"+
                            "`level` = ?,"+
                            "`stable` = ?,"+
                            "`banned` = ?,"+
                            "`enemy` = ?"+
                            " WHERE `guid` = ?;";
        PreparedStatement p = newTransact(baseQuery, dConnexion);

        p.setLong(1, acc.getBankGold());
        p.setString(2, acc.parseBankObjectsToDB());
        p.setInt(3, acc.get_Lvl());
        p.setString(4, acc.parseStable());
        p.setInt(5, (acc.isBanned()?1:0));
        p.setString(6, acc.parseEnemyListToDB());
        p.setInt(7, acc.getGUID());

        p.executeUpdate();
        closePreparedStatement(p);
    }catch(SQLException e)
    {
        LogClass.addErrorLog("MySQL ERROR: "+e.getMessage());
        e.printStackTrace();
    }
}

after much thinking and readings, I think maybe a finally catch block with a closePreparedStatement(p) inside of it would be a good idea to avoid memory leaks?

    finally
    {
        closePreparedStatement(p);
    }

If so, then I have a lot of work to do to change hundreds of methods in this way.
I’m just asking your opinion guys before I regret it later since I’m a total newbie

Need an answer please, and if you have any opinion on this piece of code about memory leaks, please don’t hesitate.

Thank you for your time.

Answer 1

You are right in your finally block assumptions. Say for example a connection is opened and then an error occurs in your code. Luckily (for some extent) you have a try catch block so you can catch and then do what you may with the error weather it be throw the error or display error or log the error or all of the above (there are many ways to deal with errors and every errors should be dealt with one way or another). Unfortunately if an error is caught in a catch block and a connection (perhaps to a database or file etc.. is still open that connections is tying up resources and impending the machine which the source is running on. Finally blocks to release this connections ARE KEY as your presumption predicts.

If there are multiple connections then the leak may be occuring elsewhere. For a rule of thumb it is good practice to use a finally block to close connections that have been opened in a try block. Happy Coding!