SQL 异常:结果集关闭后不允许操作.为什么

Question

我尝试从数据库中获取一条数据，突然它给出了错误：ResultSet 关闭后不允许操作。

while(rs3.next()) {

为什么会这样？代码似乎没问题，一切都很好。这是我的代码：

public DatabaseConnectionClass() {
    idfield = new JTextField("");
    submit = new JButton("go");
    settings = new JButton("settings");
    auto = new JButton("auto");
    add(idfield);
    add(submit);
    add(settings);
    add(auto);
    setLayout(new GridLayout());
    try {
        Class.forName("com.mysql.cj.jdbc.Driver");
        con = DriverManager.getConnection("jdbc:mysql://localhost:3306/database1?useTimezone=true&serverTimezone=UTC", "root", "");
        st = con.createStatement();
        con2 = DriverManager.getConnection("jdbc:mysql://localhost:3306/values?useTimezone=true&serverTimezone=UTC", "root", "");
        st2 = con2.createStatement();

    } catch(Exception ex) {
        System.out.println(ex);

    }
    }

这是在按下其中一个按钮(称为自动(时激活的错误方法：

 public void getAuto() throws Exception {
            for (int i = 0; i < 1000; i++) {
            String q1 = "SELECT * FROM payments LIMIT 1";
            try {
                rs3=st.executeQuery(q1);
                while(rs3.next()) {
                String ppmail = rs3.getString("mail");
                getData(ppmail);
                rs3.close();
                }} catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                System.out.println(e);
                auto.setText("End of records");
            }

            }

}

Answer 1

关闭ResultSet后，rs3.close();移动到finally块

            }} catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            System.out.println(e);
            auto.setText("End of records");
        } finally { 
             if (s3 != null){
                 s3.close();
             }
        }

立即释放此结果集对象的数据库和 JDBC 资源