java - Javaで別のタスクが開始される前に1つのタスクが完了するようにする

Question

次のタスクの開始が許可される前に、Javaで1つのタスクを強制的に完了する方法を誰かに教えてもらえますか? 具体的には、次のマークされた 2 行が呼び出される前に、最初にマークされた 2 行のコードが完全に終了するように、以下のコードを編集したいと考えています。

protected void doGet(HttpServletRequest req, HttpServletResponse resp) 
    throws ServletException, IOException {
      String idString = req.getParameter("id");
      Long id = new Long(idString);
//complete the actions specified on next two lines
      School school = new SchoolDAO().findSchool(id);
      req.setAttribute("school", school);
//before even starting the actions specified on the next two lines
      List<CourseSummary> coursesummaries = new CourseSummaryDAO().findAllcsum(id);
      req.setAttribute("coursesummaries", coursesummaries);

      jsp.forward(req, resp);
}  

---

編集：

Fernando の提案をよりよく理解するために、次のように SchoolDAO の関連部分をいくつか含めます。

public class SchoolDAO extends DataAccessObject{
    public School findSchool(Long id) {
        ResultSet rs = null;
        PreparedStatement statement = null;
        Connection connection = null;
        try {
            connection = getConnection();
            String sql = "select * from schoolprog where id=?";
            statement = connection.prepareStatement(sql);
            statement.setLong(1, id.longValue());
            rs = statement.executeQuery();
            if (!rs.next()) {return null;}
            return readSchool(rs);
         }
         catch (SQLException e) {throw new RuntimeException(e);}
         finally {close(rs, statement, connection);}
      }
      private School readSchool(ResultSet rs) throws SQLException {
          Long id = new Long(rs.getLong("id"));
          String spname = rs.getString("spname");
          String spurl = rs.getString("spurl");
          School school = new School();
          school.setId(id);
          school.setName(spname);
          school.setUrl(spurl);
          return school;
      }
}  

同様に、CourseSummaryDAO には以下が含まれます。

public class CourseSummaryDAO extends DataAccessObject{
    public List<CourseSummary> findAllcsum(Long sid) {
        LinkedList<CourseSummary> coursesummaries = new LinkedList<CourseSummary>();
        ResultSet rs = null;
        PreparedStatement statement = null;
        Connection connection = null;
        try {
            connection = getConnection(); //this is the line throwing null pointer error
      String sql = "select * from coursetotals where spid=?";
            statement = connection.prepareStatement(sql);
            statement.setLong(1, sid);
            rs = statement.executeQuery();
      //for every row, call read method to extract column 
            //values and place them in a coursesummary instance
            while (rs.next()) {
                CourseSummary coursesummary = readcsum("findAll", rs);
                coursesummaries.add(coursesummary);
            }
            return coursesummaries;
         }
         catch (SQLException e) {throw new RuntimeException(e);} 
         finally {close(rs, statement, connection);}
     }

プログラムが壊れている行は次のとおりです。

connection = getConnection(); //