createStatement SQL ResultSet next（）返回false

Question

我继续测试此连接ResultSet，而System.out.println(rs)返回oracle.jdbc.driver.ForwardOnlyResultSet@2aa5fe93

System.out.println(rs.next())给我虚假

我的输出是：

Exception in thread "main" java.lang.NullPointerException
    at com.prjzr.Driver.main(Driver.java:31)

public class UserDaoImpl implements UserDao {

    public List<User> getUser() {
        // TODO Auto-generated method stub

        List<User> users = new ArrayList<>();

        String sql = "SELECT * FROM USERPROFILE";

        try(Connection conn = DatabaseAccessUtil.getHardCodedConnection(); 
            Statement s = conn.createStatement();
            ResultSet rs = s.executeQuery(sql);){

        //  System.out.println(rs);
        while(rs.next()) {

            int recNumber = rs.getInt("RECNUMBER");
            String username = rs.getString("USERID");
            String acctHldrFirstName = rs.getString("ACCOUNTHOLDERFIRSTNAME");
            String acctHldrFirstLast = rs.getString("ACCOUNTHOLDERLASTNAME");
            String acctHldrMailing = rs.getString("ACOUNTHOLDERMAILING");
            String primaryAcctKey = rs.getString("PRIMARYACCTNUMBER");
            String userPassword = rs.getString("PASSWORD");
            users.add(new User(recNumber, username,  acctHldrFirstName, acctHldrFirstLast, acctHldrMailing, primaryAcctKey, userPassword));

        }


        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return null;
    }

我看过另一个问题，他们的问题与此问题略有不同。 如何读取我的记录并摆脱

Exception in thread "main" java.lang.NullPointerException
    at com.prjzr.Driver.main(Driver.java:31)