JDBCでmysql自動インクリメントのid番号を取得

PreparedStatement pstmt = conn.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS);
ResultSet rsKey = pstmt.getGeneratedKeys();
rsKey.next();
int key = rsKey.getInt(1);
stmt.executeUpdate("update article set rootid = " + key + " where id = " + key);