具有自定义单元格的javafx listview

Question

我正在尝试将自定义单元格插入到列表视图中，我试图在此处查看类似的问题，但它们似乎仅处理字符串数据

我以以下指南为基础来尝试此https://www.turais.de/how-to-custom-listview-cell-in-javafx/ 无论我尝试什么，似乎都没有数据传递到updateItem，所以我一直收到此错误日志

Exception in Application start method
java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
    at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at un.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
Caused by: java.lang.RuntimeException: Exception in Application start method
    at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$1(LauncherImpl.java:182)
    at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException
    at message.stick.ContactCellController.updateItem(ContactCellController.java:44)
    at message.stick.ContactCellController.updateItem(ContactCellController.java:24)
    at javafx.scene.control.ListCell.updateItem(ListCell.java:480)
    at javafx.scene.control.ListCell.access$300(ListCell.java:72)
    at javafx.scene.control.ListCell$4.invalidated(ListCell.java:299)
    at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:111)
    at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:146)
    at javafx.scene.control.ListCell.setListView(ListCell.java:305)
    at javafx.scene.control.ListCell.updateListView(ListCell.java:494)
    at com.sun.javafx.scene.control.skin.ListViewSkin.createCell(ListViewSkin.java:292)
    at com.sun.javafx.scene.control.skin.ListViewSkin.lambda$new$2(ListViewSkin.java:99)
    at com.sun.javafx.scene.control.skin.VirtualFlow.getCell(VirtualFlow.java:1777)
    at com.sun.javafx.scene.control.skin.VirtualFlow.getCellLength(VirtualFlow.java:1879)
    at com.sun.javafx.scene.control.skin.VirtualFlow.computeViewportOffset(VirtualFlow.java:2528)
    at com.sun.javafx.scene.control.skin.VirtualFlow.layoutChildren(VirtualFlow.java:1189)
    at javafx.scene.Parent.layout(Parent.java:1087)
    at javafx.scene.Parent.layout(Parent.java:1093)
    at javafx.scene.Parent.layout(Parent.java:1093)
    at javafx.scene.Scene.doLayoutPass(Scene.java:552)
    at javafx.scene.Scene.preferredSize(Scene.java:1646)
    at javafx.scene.Scene.impl_preferredSize(Scene.java:1720)
    at javafx.stage.Window$9.invalidated(Window.java:864)
    at javafx.beans.property.BooleanPropertyBase.markInvalid(BooleanPropertyBase.java:109)
    at javafx.beans.property.BooleanPropertyBase.set(BooleanPropertyBase.java:144)
    at javafx.stage.Window.setShowing(Window.java:940)
    at javafx.stage.Window.show(Window.java:955)
    at javafx.stage.Stage.show(Stage.java:259)
    at message.stick.MessageStick.start(MessageStick.java:31)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$8(LauncherImpl.java:863)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$7(PlatformImpl.java:326)
    at com.sun.javafx.application.PlatformImpl.lambda$null$5(PlatformImpl.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$6(PlatformImpl.java:294)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
    at com.sun.glass.ui.gtk.GtkApplication.lambda$null$10(GtkApplication.java:245)
    ... 1 more

以下是我的contactCellController和MainWindowController的代码的当前状态 ContactCellController

import eu.hansolo.tilesfx.addons.Indicator;
import java.io.IOException;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.control.Label;
import javafx.scene.control.ListCell;
import javafx.scene.layout.AnchorPane;

/**
 * FXML Controller class
 *
 * @author james
 */
public class ContactCellController extends ListCell<Contacts>
{

    @FXML
    private Indicator statusIndicator;
    @FXML
    private Label usernameLabel;
    @FXML
    private Label statusMessageLabel;

    private AnchorPane anchorPane;
    private FXMLLoader mlLoader;
    /**
     * Initializes the controller class.
     */

    @Override
    protected void updateItem(Contacts contact, boolean empty)
    {
        System.out.println("boolean empty variable value: " + empty);
        System.out.println("Contact Contents: " + contact.toString());
        super.updateItem(contact, empty);

        if (empty )//|| contact == null)
        {
            System.out.println("empty value is true");
            setText(null);
            setGraphic(null);
        }
        else
        {
            System.out.println("contact isn't null or empty is false");
            if (mlLoader == null)
            {
                mlLoader = new FXMLLoader(getClass().getResource("contactCell.fxml"));
                //mlLoader.setController(this);

                try
                {
                    mlLoader.load();
                    usernameLabel.setText(contact.getUsername());
                    statusMessageLabel.setText(contact.getStatusMessage());
                }
                catch (IOException ex)
                {
                    System.out.println("Contact cell error in updateItem");
                    ex.printStackTrace();
                }
            }
            else
            {
                setText(null);
                setGraphic(anchorPane);
            }
        }
    }
}

MainWindowController

import java.net.URL;
import java.util.ResourceBundle;
import javafx.collections.FXCollections;
import javafx.fxml.Initializable;
import javafx.scene.control.ListView;
import javafx.fxml.FXML;
import javafx.scene.control.ListCell;
import javafx.util.Callback;
import javafx.collections.ObservableList;


/**
 * FXML Controller class
 *
 * @author james
 */
public class MainWindowController implements Initializable
{

    @FXML
    private ListView myListView;

    private ObservableList<Contacts> contactsObservableList = FXCollections.observableArrayList();
    /**
     * Initializes the controller class.
     */
    @Override
    public void initialize(URL url, ResourceBundle rb)
    {
        setupData();
        myListView.setItems(contactsObservableList);
        myListView.setCellFactory(new Callback<ListView<Contacts>, ListCell<Contacts>>()
        {
            @Override
            public ListCell<Contacts> call(ListView<Contacts> contactsListView)
            {
                return new ContactCellController();
            }
        });
    }


    private void setupData()
    {  
        contactsObservableList.addAll(
            new Contacts("James", "Available",Contacts.Status.online),
            new Contacts("Jimmy", "unavailable", Contacts.Status.offline));
        System.out.println("contactsObservableList number of entries: " + contactsObservableList.size());
    }
}

如果有人可以指出错误，那么我需要修复，并且可能是一个很棒的解决方案。

最佳问候 詹姆斯