JavaFX-单击tableView中的空行时setOnMouseClicked中出错

单击表上的空行时，setOnMouseClicked出现错误。 只有在运行代码后第一次单击空行时才会发生这种情况

我的方法是：

table.setOnMouseClicked(e -> {
                try {
                    User selected = table.getSelectionModel().getSelectedItem();
                    String query = "SELECT * FROM persons WHERE PersonID=?";
                    pst = conn.prepareStatement(query);
                    pst.setString(1, selected.getPersonID());
                    rs = pst.executeQuery();

                    while (rs.next()) {
                        txtFirstName.setText(rs.getString("Firstname"));
                        txtLastName.setText(rs.getString("Lastname"));
                        ((TextField) txtDob.getEditor()).setText(selected.getDob());    
                    }

                    pst.close();
                    rs.close();
                } catch (SQLException ex) {
                    ex.printStackTrace();
                }
            });

这是我在控制台中得到的。这只有在我点击时才会发生 我怎样才能解决这个问题

Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
    at application.Main.lambda$8(Main.java:266)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
    at javafx.event.Event.fireEvent(Event.java:198)
    at javafx.scene.Scene$ClickGenerator.postProcess(Scene.java:3470)
    at javafx.scene.Scene$ClickGenerator.access$8100(Scene.java:3398)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3766)
    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$MouseEventNotification.run(GlassViewEventHandler.java:381)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$354(GlassViewEventHandler.java:417)
    at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:416)
    at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
    at com.sun.glass.ui.View.notifyMouse(View.java:937)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
    at java.lang.Thread.run(Thread.java:748)

---

您正在选择一个空行，这意味着所选的.getPersonID（）正在尝试调用null对象上的方法。尝试添加一个条件，以确保所选行与null不同

添加以下内容：

if(selected != null)

--

table.setOnMouseClicked(e -> {
                try {
                    User selected = table.getSelectionModel().getSelectedItem();
                    if(selected != null) {
                    String query = "SELECT * FROM persons WHERE PersonID=?";
                    pst = conn.prepareStatement(query);
                    pst.setString(1, selected.getPersonID());
                    rs = pst.executeQuery();

                    while (rs.next()) {
                        txtFirstName.setText(rs.getString("Firstname"));
                        txtLastName.setText(rs.getString("Lastname"));
                        ((TextField) txtDob.getEditor()).setText(selected.getDob());    
                    }

                    pst.close();
                    rs.close();
                   }
                } catch (SQLException ex) {
                    ex.printStackTrace();
                }
            });