JavaFX构造函数中的SQLException

我创建了一个场景，显示从数据库中获取的数据。此数据被分配给名为“Details（）”的构造函数中的变量。 构造函数接受一个参数“rollNo”。我应该根据“rollNo”将数据库查询中的数据分配给构造函数中的变量

我不明白为什么会给出SQLException

请帮忙

public class Details extends Application {

static Connection con = ConnectionUtil.getDataBaseConnection();
String query = "SELECT * from student WHERE rno = ?";

ResultSet rs;

PreparedStatement pst;

public static String name;
public static String course;
public static String roll;
public static String address;
public static String phone;
public static String yoj;
public static String parent;
public static String parPhone;
public static String attendance;


    Details(String rollNo) {
     System.out.println("Details rollNo = " + rollNo);
     try {
            roll = rollNo;

            pst = con.prepareStatement(query);
            pst.setString(1, rollNo);

            rs = pst.executeQuery();

            name = rs.getString("name");
            course = rs.getString("course");
            roll = rs.getString("rno");
            address = rs.getString("address");
            phone = rs.getString("contact");
            yoj = rs.getString("yoj");
            parent = rs.getString("prntName");
            parPhone = rs.getString("prntCntct");
            attendance = rs.getString("classesAttended");
            System.out.println("***" + rs.getString("name") + "***");

        } catch (SQLException e) {
            e.printStackTrace();
        }
}


@Override
public void start(Stage primaryStage) {
    try {



        Parent root = FXMLLoader.load(getClass().getResource("/FXML/Details.fxml"));
        Scene scene = new Scene(root,750,420);
        primaryStage.setScene(scene);
        primaryStage.setTitle("Attendance AITH");
        primaryStage.show();
    } catch(Exception e) {
        e.printStackTrace();
    }
}

public static void main(String[] args) {
    launch(args);
}

它在控制台上提供以下输出：

    Details rollNo = 3
    java.sql.SQLException: Before start of result set
        at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129)
        at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
        at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89)
        at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:63)
        at com.mysql.cj.jdbc.result.ResultSetImpl.checkRowPos(ResultSetImpl.java:516)
        at com.mysql.cj.jdbc.result.ResultSetImpl.getString(ResultSetImpl.java:944)
        at com.mysql.cj.jdbc.result.ResultSetImpl.getString(ResultSetImpl.java:966)
        at application.Details.<init>(Details.java:45)
        at application.StudentTableUtil$3$1.lambda$0(StudentTableUtil.java:150)
        at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
        at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
        at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
        at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
        at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
        at javafx.event.Event.fireEvent(Event.java:198)
        at javafx.scene.Node.fireEvent(Node.java:8411)
        at javafx.scene.control.Button.fire(Button.java:185)
        at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182)
        at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:96)
        at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
        at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
        at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
        at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
        at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
        at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
        at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
        at javafx.event.Event.fireEvent(Event.java:198)
        at javafx.scene.Scene$MouseHandler.process(Scene.java:3757)
        at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
        at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
        at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
        at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:394)
        at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
        at java.security.AccessController.doPrivileged(Native Method)
        at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$353(GlassViewEventHandler.java:432)
        at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
        at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:431)
        at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
        at com.sun.glass.ui.View.notifyMouse(View.java:937)
        at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
        at com.sun.glass.ui.gtk.GtkApplication.lambda$null$48(GtkApplication.java:139)
        at java.lang.Thread.run(Thread.java:748)
    controller Details.name=null
    ****************************3***********

详细信息rollNo=3
java.sql.SQLException:在结果集开始之前
位于com.mysql.cj.jdbc.exceptions.SQLError.createSQLException（SQLError.java:129）
位于com.mysql.cj.jdbc.exceptions.SQLError.createSQLException（SQLError.java:97）
位于com.mysql.cj.jdbc.exceptions.SQLError.createSQLException（SQLError.java:89）
位于com.mysql.cj.jdbc.exceptions.SQLError.createSQLException（SQLError.java:63）
位于com.mysql.cj.jdbc.result.ResultSetImpl.checkRowPos（ResultSetImpl.java:516）
位于com.mysql.cj.jdbc.result.ResultSetImpl.getString（ResultSetImpl.java:944）
位于com.mysql.cj.jdbc.result.ResultSetImpl.getString（ResultSetImpl.java:966）
at application.Details.（Details.java:45）
在application.StudentTableUtil$3$1.lambda$0（StudentTableUtil.java:150）
在com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent（CompositeEventHandler.java:86）上
位于com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent（EventHandlerManager.java:238）
位于com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent（EventHandlerManager.java:191）
在com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent（CompositeEventDispatcher.java:59）上
在com.sun.javafx.event.BasicEventDispatcher.dispatchEvent（BasicEventDispatcher.java:58）
位于com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent（EventDispatchChainImpl.java:114）
在com.sun.javafx.event.BasicEventDispatcher.dispatchEvent（BasicEventDispatcher.java:56）
位于com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent（EventDispatchChainImpl.java:114）
在com.sun.javafx.event.BasicEventDispatcher.dispatchEvent（BasicEventDispatcher.java:56）
位于com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent（EventDispatchChainImpl.java:114）
在com.sun.javafx.event.BasicEventDispatcher.dispatchEvent（BasicEventDispatcher.java:56）
位于com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent（EventDispatchChainImpl.java:114）
在com.sun.javafx.event.BasicEventDispatcher.dispatchEvent（BasicEventDispatcher.java:56）
位于com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent（EventDispatchChainImpl.java:114）
在com.sun.javafx.event.BasicEventDispatcher.dispatchEvent（BasicEventDispatcher.java:56）
位于com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent（EventDispatchChainImpl.java:114）
在com.sun.javafx.event.BasicEventDispatcher.dispatchEvent（BasicEventDispatcher.java:56）
位于com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent（EventDispatchChainImpl.java:114）
位于com.sun.javafx.event.EventUtil.fireventimpl（EventUtil.java:74）
位于com.sun.javafx.event.EventUtil.firevent（EventUtil.java:49）
位于javafx.event.event.fireEvent（event.java:198）
位于javafx.scene.Node.firevent（Node.java:8411）
位于javafx.scene.control.Button.fire（Button.java:185）
在com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased上（ButtonBehavior.java:182）
位于com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle（BehaviorSkinBase.java:96）
位于com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle（BehaviorSkinBase.java:89）
位于com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent（CompositeEventHandler.java:218）
位于com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent（CompositeEventHandler.java:80）
位于com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent（EventHandlerManager.java:238）
位于com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent（EventHandlerManager.java:191）
在com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent（CompositeEventDispatcher.java:59）上
在com.sun.javafx.event.BasicEventDispatcher.dispatchEvent（BasicEventDispatcher.java:58）
位于com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent（EventDispatchChainImpl.java:114）
在com.sun.javafx.event.BasicEventDispatcher.dispatchEvent（BasicEventDispatcher.java:56）
位于com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent（EventDispatchChainImpl.java:114）
在com.sun.javafx.event.BasicEventDispatcher.dispatchEvent（BasicEventDispatcher.java:56）
位于com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent（EventDispatchChainImpl.java:114）
在com.sun.javafx.event.BasicEventDispatcher.dispatchEvent（BasicEventDispatcher.java:56）
位于com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent（EventDispatchChainImpl.java:114）
在com.sun.javafx.event.BasicEventDispatcher.dispatchEvent（BasicEventDispatcher.java:56）
位于com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent（EventDispatchChainImpl.java:114）
在com.sun.javafx.event.BasicEventDispatcher.dispatchEvent（BasicEventDispatcher.java:56）
位于com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent（EventDispatchChainImpl.java:114）
在com.sun.javafx.event.BasicEventDispatcher.dispatchEvent（BasicEventDispatcher.java:56）
位于com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent（EventDispatchChainImpl.java:114）
位于com.sun.javafx.event.EventUtil.fireventimpl（EventUtil.java:74）
位于com.sun.javafx.event.EventUtil.firevent（EventUtil.java:54）
位于javafx.event.event.fireEvent（event.java:198）
位于javafx.scene.scene$MouseHandler.process（scene.java:3757）
在javafx.scene。