如何在Java JDBC中显示resultset中的arrayList内容？

因此，我正在制作一个简单的java项目，在glassfish中使用JDBC，看看它是如何工作的。该程序仅为您选择的调查显示调查列表和问题列表。但是，我似乎无法显示所选调查的问题列表。我总是得到空值。以下是我创建的方法：

将结果集转换为对象模型数据值

public JHAKSurvey findSurvey(long id) {
    System.out.println("JDBC: FIND SURVEY");
    Connection connection = null;
    PreparedStatement ps = null;
    ResultSet rs = null;
    JHAKSurvey survey = null;
    try {
        connection = openConnection();
        String query = "SELECT * FROM APP.SURVEY WHERE ID=?";
        ps = connection.prepareStatement(query);
        ps.setLong(1, id);
        rs = ps.executeQuery();
        while (rs.next()) {
            survey = createSurveyFromResultSet(rs);             
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        closeConnection(connection);
    }
    return survey;
}

从问题表中查询调查id问题列表的专用方法

private void findQuestionsBySurvey(JHAKSurvey survey){
    System.out.println("JDBC: FIND QUESTIONS BY SURVEY");
    Connection connection = null;
    PreparedStatement ps = null;

    try {
        connection = openConnection();
        String query = "SELECT * FROM APP.QUESTION WHERE SURVEYID=?";
        ps = connection.prepareStatement(query);
        ps.setLong(1, survey.getId());
        ps.executeQuery(query);
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        closeConnection(connection);
    }

}

将“查找结果集”列表转换为问题对象并将其添加到调查对象的私有方法

private void createQuestionFromResultSet(ResultSet rs, JHAKSurvey survey){
    ArrayList<JHAKQuestion> qList = new ArrayList<JHAKQuestion>();      
    JHAKQuestion question = new JHAKQuestion();
    JHAKSurvey ss = new JHAKSurvey();
    //qList.add(survey.getQuestions());

    try {
        while (rs.next()) {
            //question.setDescription(qList.toString());
            question.setId(rs.getLong("ID"));
            question.setDescription(rs.getString("DESCRIPTION"));
            qList.add(question);
            survey.setQuestions(qList);
        }               
        System.out.println("createQuestionFromResultSet : JDBC : successful");
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        System.out.println("createQuestionFromResultSet : JDBC : fail");
        e.printStackTrace();
    }
}

我错过了什么？我似乎也有错误：

cannot convert from void to JHAKQuestion

当我尝试以下方法时：createQuestionFromResultSet（）

谢谢你

看看你的方法：

private void findQuestionsBySurvey(JHAKSurvey survey){

您希望获取调查的问题，但该方法返回void。使其返回一个

列表

。在方法体中，迭代结果集，将每一行转换为一个问题，将问题添加到

列表

，然后返回该列表

或者，如果该方法的目标是向作为参数传递的调查中添加问题，则将该方法重命名为

private void addQuestionsToSurvey(JHAKSurvey survey) {

并且，在方法体内部，调用方法

createQuestionFromResultSet

（该方法应命名为

createquestionsfromResultSet，并将其添加到survey

），将结果集和调查作为参数：

private void findQuestionsBySurvey(JHAKSurvey survey){
    System.out.println("JDBC: FIND QUESTIONS BY SURVEY");
    Connection connection = null;
    PreparedStatement ps = null;

    try {
        connection = openConnection();
        String query = "SELECT * FROM APP.QUESTION WHERE SURVEYID=?";
        ps = connection.prepareStatement(query);
        ps.setLong(1, survey.getId());
        ResultSet rs = ps.executeQuery(query);
        createQuestionFromResultSet(survey); 
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        closeConnection(connection);
    }

}

private void findQuestionsBySurvey(JHAKSurvey survey){
    System.out.println("JDBC: FIND QUESTIONS BY SURVEY");
    Connection connection = null;
    PreparedStatement ps = null;

    try {
        connection = openConnection();
        String query = "SELECT * FROM APP.QUESTION WHERE SURVEYID=?";
        ps = connection.prepareStatement(query);
        ps.setLong(1, survey.getId());
        ResultSet rs = ps.executeQuery(query);
        createQuestionFromResultSet(survey); 
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        closeConnection(connection);
    }

}