Question

I have to modify a few tables in one function. They must all succeed, or all fail. If one operation fails, I want them all to fail. I have the following:

public void foo() throws Exception {
    Connection conn = null;
    try {
        conn = ...;
        conn.setAutoCommit(false);
        grok(conn);
        conn.commit();
    }
    catch (Exception ex) {
        // do I need to call conn.rollback() here?
    }
    finally {
        if (conn != null) {
            conn.close();
            conn = null;
        }
    }
}

private void grok(Connection conn) throws Exception {
    PreparedStatement stmt = null;
    try {
        // modify table "apple" 
        stmt = conn.prepareStatement(...);
        stmt.executeUpdate();
        stmt.close();

        // modify table "orange"
        stmt = conn.prepareStatement(...);
        stmt.executeUpdate();
        stmt.close();

        ...
    }
    finally {
        if (stmt != null) {
            stmt.close();
        }
    }
}

I’m wondering if I need to call rollback() in the case that something goes wrong during this process.

Other info: I’m using connection pooling. In the sample above, I’m also making sure to close each PreparedStatement using finally statements as well, just left out for brevity.

Thank you

Answer 1

You don’t need to call rollback(). If the connection closes without completing commit() it will be rolled back.

You don’t need to set conn to null either; and since the try block starts after conn is initialized (assuming ... cannot evaluate to null) you don’t need the != null in finally either.