List<topic> topices = new ArrayList<topic>();
    topices=topic.getTopic();

public static List<topic> getTopic() {
        List<topic> topices = new ArrayList<topic>();
        Connection conn = DB.getConn();
        String sql = "select * from topic";
        Statement stmt = DB.getStatement(conn);
        ResultSet rs = DB.getResultSet(stmt, sql);
        try {
            while (rs.next()) {
                topic t = new topic();
                t.setSid(rs.getInt("sid"));
                t.setUid(rs.getInt("uid"));
                t.setTitle(rs.getString("title"));
                t.setContent(rs.getString("content"));
                t.setPosttime(rs.getTimestamp("posttime"));
                t.setClickcount(rs.getInt("clickcount"));
                t.setLastreply(rs.getTimestamp("lastreply"));
                t.setIstop(rs.getBoolean("istop"));
                t.setIsgood(rs.getBoolean("isgood"));
                t.setLevel(rs.getInt("level"));
                topices.add(t);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DB.close(rs);
            DB.close(stmt);
            DB.close(conn);
        }
        return topices;
    }