如何通过按钮单击移动结果集光标，并在文本字段中显示数据

Question

所以，我正在创建一个桌面银行应用程序。没什么大不了的，我只是想练习一下，变得更好。

// Method I use to get a connection. I know this works.
public static Connection getConnection() throws SQLException {
    String sCon = "jdbc:sqlite:banking.sqlite";
    Connection connection = DriverManager.getConnection(sCon);
    return connection;
}
.
..
... 
.....Other code

方法 I 尝试用于创建和操作结果集中的数据。
我认为问题从这里开始。使用此代码，我只能返回结果集的一行，并且只能返回最后一行。

public static Customers getAccounts(Customers c) {
    String query = "select RowCount, Customers.Account_Number, "
            + "Customers.First_Name, Last_Name, Address, "
            + "Phone_Number, Accounts.Balance "
            + "from Customers "
            + "join Accounts ";
    try (Connection connection = getConnection();
            PreparedStatement ps = connection.prepareStatement(query);
            ResultSet rs = ps.executeQuery()) {
        while (rs.next()) {
            String fName = rs.getString("First_Name");
            String lName = rs.getString("Last_Name");
            String address = rs.getString("Address");
            String phone = rs.getString("Phone_Number");
            String accNum = rs.getString("Account_Number");
            String balance = rs.getString("Balance");

            c.setFirstName(fName);
            c.setLastName(lName);
            c.setAddress(address);
            c.setPhoneNumber(phone);
            c.setAccountNumber(accNum);
            c.setBalance(balance);
        }
        return c;
    } catch (SQLException e) {
        System.err.println(e);
    }
    return null;
}
}

这是链接到我用来执行我尝试尝试的按钮的方法。它是控制器类的一部分。我相信这种方法也是问题的一部分。有什么想法吗？感谢你们所做的一切。这个网站对社区来说是一个真正的好处。

public void next() {
   Customers c = new Customers();
   DBInterface.getAccounts(c);
    firstNameF2.setText(c.getFirstName());
    lastNameF2.setText(c.getLastName());
    addressF2.setText(c.getAddress());
    phoneNumberF2.setText(c.getPhoneNumber());
    accNumF.setText(c.getAccountNumber());
    balanceF.setText(c.getBalance());
}

Answer 1

如果您希望获得多个Customers对象，那么您绝对应该返回一个列表。

public static List<Customers> getAccounts() {
    // Whatever you originally had...
    final List<Customers> ret = new ArrayList<>();
    while (rs.next()) {
        String fName = rs.getString("First_Name");
        String lName = rs.getString("Last_Name");
        String address = rs.getString("Address");
        String phone = rs.getString("Phone_Number");
        String accNum = rs.getString("Account_Number");
        String balance = rs.getString("Balance");
        final Customers cust = new Customers();
        cust.setFirstName(fName);
        cust.setLastName(lName);
        cust.setAddress(address);
        cust.setPhoneNumber(phone);
        cust.setAccountNumber(accNum);
        cust.setBalance(balance);
        ret.add(cust);
    }
    return ret;
}

我已经删除了关于在Customers实例中传递的部分(最终会传递List<Customers>.如果您确实需要这样做，您可以重新添加并进行所有必要的检查。