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Java NullPointerException TavleView.setItem(FXCollections.observableArrayList())

转载 作者：行者123 更新时间：2023-12-01 09:14:38 27 4
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我想在我的表格中添加一列(personTable中的Personen_detailController)，但是当我设置ObservableList<>时它告诉我NullPointerException 。我需要的人在 List 中当我这样做时，它给了我正确的参数 System.out.println(per.getPersonId()) 。

我不知道我做错了什么，因为在我的 PersonenController 中我做了同样的事情并且它有效。

我会发布每门必要的类(class)。感谢您的帮助。

人员 Controller :

package dummy.dummy.dummy.personen;

import dummy.dummy.InformationDialog;
import dummy.model.Person;
import java.net.URL;
import java.util.ArrayList;
import java.util.ResourceBundle;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Alert;
import javafx.scene.control.Button;
import javafx.scene.control.ContentDisplay;
import javafx.scene.control.TableCell;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.TextField;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.util.Callback;

/**
 * FXML Controller class
 *
 * @author z0035ddc
 */
public class PersonenController implements Initializable {

    String filterText = null;

    ArrayList<Person> PerList;
    ObservableList<Person> personSuchList = FXCollections.observableArrayList();

    Personen_detailController detailController = new Personen_detailController();


    @FXML
    TableView<Person> personSuchTable;


    @FXML
    TextField Name_TextFeld;
    @FXML
    TextField Kurzname_TextFeld;


    @Override
    public void initialize(URL url, ResourceBundle rb) {

    }    

    @FXML
    private void search() {

        if(!Name_TextFeld.getText().equals("") && Kurzname_TextFeld.getText().equals("")){ // Falls nach Name gesucht wird
            filterText = Name_TextFeld.getText();
            filterText = filterText.replace("*", "%");
            perListByName();
        }else if(!Kurzname_TextFeld.getText().equals("") && Name_TextFeld.getText().equals("")){ // Falls nach Kurnamen gesucht wird
            filterText = Kurzname_TextFeld.getText();
            filterText = filterText.replace("*", "%");
            perListByShortname();
        }else if(Name_TextFeld.getText().equals("") && Kurzname_TextFeld.getText().equals("")){ // Falls Textfelder nicht befüllt
            InformationDialog dia = new InformationDialog(Alert.AlertType.INFORMATION, "Bitte geben Sie einen Namen bzw. Kurznamen ein.");
        }else if(!Name_TextFeld.getText().equals("") && !Kurzname_TextFeld.getText().equals("")){ // Falls beide Textfelder befüllt
            InformationDialog dia = new InformationDialog(Alert.AlertType.INFORMATION, "Es dürfen nicht gleichzeitig Name und Kurzname gefüllt sein.");
        }

        /*****************************FEHLER!!!***************************/

        if(!PerList.isEmpty()){

            personSuchList.clear();
            personSuchTable.getColumns().clear();

            for (Person per : PerList) {
                personSuchList.add(per);
            }

            personSuchTable.setItems(personSuchList);
            initTable();


        }else{

            InformationDialog dia = new InformationDialog(Alert.AlertType.INFORMATION, "Person wurde nicht gefunden.");

        }

    }

    private void perListByName(){
        PerList = new ArrayList<>();
        PerList = Person.getListPersonenAndDoQueryByName(filterText);
    }

    private void perListByShortname(){
        PerList = new ArrayList<>();
        PerList = Person.getListPersonenAndDoQueryByShortname(filterText);
    }    

    @FXML
    private void searchByEnter(KeyEvent event){
        if (event.getCode() == KeyCode.ENTER || event == null) {
            search();
        }
    }

    @FXML
    private void initTable() {
                //Erste Spalte                
                TableColumn personId = new TableColumn();
                personId.setText("Person_ID");
                personId.setMinWidth(50);
                personId.setCellValueFactory(new PropertyValueFactory("personId"));
                personSuchTable.getColumns().add(personId);

                //Zweite Spalte

                TableColumn kurzname = new TableColumn();
                kurzname.setText("Kurzname");
                kurzname.setMinWidth(50);
                kurzname.setCellValueFactory(new PropertyValueFactory("kurzname"));
                personSuchTable.getColumns().add(kurzname);

                //dritte Spalte

                TableColumn name = new TableColumn();
                name.setText("NAME");
                name.setMinWidth(100);
                name.setCellValueFactory(new PropertyValueFactory("name"));
                personSuchTable.getColumns().add(name);

                //vierte Spalte

                TableColumn Land = new TableColumn();
                Land.setText("Land");
                Land.setMinWidth(50);
                Land.setCellValueFactory(new PropertyValueFactory("land"));
                personSuchTable.getColumns().add(Land);

                //fünfte Spalte

                TableColumn sperre = new TableColumn();
                sperre.setText("Gesperrt");
                sperre.setMinWidth(5);
                sperre.setCellValueFactory(new PropertyValueFactory("sperre"));
                personSuchTable.getColumns().add(sperre);

                //fünfte Spalte

                TableColumn<Person, Boolean> detail = new TableColumn<>();
                detail.setText("");
                detail.setMinWidth(150);
                Callback<TableColumn<Person, Boolean>, TableCell<Person, Boolean>> detailsColumnCellFactory = //
                new Callback<TableColumn<Person, Boolean>, TableCell<Person, Boolean>>() {

            @Override
            public TableCell call(final TableColumn param) {
                final TableCell cell = new TableCell() {

                    @Override
                    public void updateItem(Object item, boolean empty) {
                        super.updateItem(item, empty);
                        if (empty) {
                            setText(null);
                            setGraphic(null);
                        } else {
                            final Button btnDetail = new Button("Details");
                            btnDetail.setOnAction(new EventHandler<ActionEvent>() {

                                @Override
                                public void handle(ActionEvent event) {
                                    param.getTableView().getSelectionModel().select(getIndex());
                                    Person item = personSuchTable.getSelectionModel().getSelectedItem();
                                    if (item != null) {

                                        detailController.openNewPersonTab(item);
                                    }
                                }
                            });
                            setGraphic(btnDetail);
                            setContentDisplay(ContentDisplay.GRAPHIC_ONLY);
                        }
                    }
                };
                return cell;
            }
        };
        detail.setCellFactory(detailsColumnCellFactory);
        personSuchTable.getColumns().add(detail);
    }   
}

在第 196 行，我调用我的 Person_detailController 类 ( detailController.openNewPersonTab(item); )。

Personen_detailController:

package admintool.ui.stammdaten.personen;

import admintool.AdminTool;
import admintool.helpers.ExceptionDialog;
import admintool.model.Person;
import admintool.ui.steuerdaten.benutzerverwaltung.BenutzerSucheController;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.control.Alert;
import javafx.scene.control.Tab;
import javafx.scene.control.TabPane;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.TextField;
import javafx.scene.control.cell.PropertyValueFactory;

/**
 *
 * @author z0035ddc
 */
public class Personen_detailController {

    Person per;

    @FXML
    TableView<Person> personTable;

    ObservableList<Person> personList = FXCollections.observableArrayList();

    @FXML
    TextField name_TextFeld_detail;
    @FXML
    TextField land_TextFeld_detail;
    @FXML
    TextField personId_TextFeld_detail;
    @FXML
    TextField sperre_TextFeld_detail;
    @FXML
    TextField windowsKennung_TextFeld_detail;

    @FXML
    public void openNewPersonTab(Person per) {
        try {
            //System.out.println(per.getName());
            FXMLLoader loader =new FXMLLoader(getClass().getResource("/admintool/ui/stammdaten/personen/personen_detail.fxml"));

            TabPane tp = AdminTool.getRootlayoutPane();
            Tab newTab = new Tab(per.getName());
            newTab.setContent(loader.load());
            tp.getTabs().add(newTab);
            tp.getSelectionModel().select(newTab);



            personList.add(per);

            System.out.println(per.getPersonId());

            personTable.setItems(personList);

            Personen_detailController controller = loader.<Personen_detailController>getController();
            controller.initData(per);

        } catch (IOException ex) {
            Logger.getLogger(BenutzerSucheController.class.getName()).log(Level.SEVERE, null, ex);
            ExceptionDialog dia = new ExceptionDialog(Alert.AlertType.ERROR, ex);

        }
    }

    @FXML
    private void initData(Person per) {
        this.per = per;

        this.name_TextFeld_detail.setText(per.getName());
        this.land_TextFeld_detail.setText(per.getLand());

        this.personId_TextFeld_detail.setText(per.getPersonId().toString());
        this.sperre_TextFeld_detail.setText(per.getSperre().toString());
        this.windowsKennung_TextFeld_detail.setText(per.getOsKennung());

        //Erste Spalte                
       /* TableColumn vertragspartnerColumn = new TableColumn();
        vertragspartnerColumn.setText("Vertragspartner");
        vertragspartnerColumn.setMinWidth(50);
        vertragspartnerColumn.setCellValueFactory(new PropertyValueFactory("vertragspartner"));
        personTable.getColumns().add(vertragspartnerColumn);*/

        //Erste Spalte                
        TableColumn personId = new TableColumn();
        personId.setText("Person_ID");
        personId.setMinWidth(50);
        personId.setCellValueFactory(new PropertyValueFactory("personId"));
        personTable.getColumns().add(personId);
    }

}

错误出现在第 69 行 ( personTable.setItems(personList); )。

至少还有错误:

Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
at dummy.dummy.dummy.personen.Personen_detailController.openNewPersonTab(Personen_detailController.java:69)
at dummy.dummy.dummy.personen.PersonenController$1$1$1.handle(PersonenController.java:196)
at dummy.dummy.dummy.personen.PersonenController$1$1$1.handle(PersonenController.java:188)
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.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.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$MouseEventNotification.run(GlassViewEventHandler.java:380)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:294)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$354(GlassViewEventHandler.java:416)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:415)
at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
at com.sun.glass.ui.View.notifyMouse(View.java:937)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
at java.lang.Thread.run(Thread.java:745)

personen_detail.fxml:

<?xml version="1.0" encoding="UTF-8"?>

<?import java.net.URL?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.SplitPane?>
<?import javafx.scene.control.Tab?>
<?import javafx.scene.control.TabPane?>
<?import javafx.scene.control.TableView?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.AnchorPane?>

<AnchorPane id="AnchorPane" prefHeight="882.0" prefWidth="1294.0" styleClass="mainFxmlClass" xmlns="http://javafx.com/javafx/8.0.60" xmlns:fx="http://javafx.com/fxml/1" fx:controller="admintool.ui.stammdaten.personen.Personen_detailController">
    <stylesheets>
        <URL value="@personen.css" />
    </stylesheets>
   <children>
      <TabPane fx:id="tabPane" prefHeight="882.0" prefWidth="1294.0" tabClosingPolicy="UNAVAILABLE" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
        <tabs>
          <Tab closable="false" text="Details">
            <content>
              <AnchorPane minHeight="0.0" minWidth="0.0" prefHeight="180.0" prefWidth="200.0">
                     <children>
                        <SplitPane dividerPositions="0.2291421856639248" layoutX="151.0" layoutY="82.0" orientation="VERTICAL" prefHeight="853.0" prefWidth="1294.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
                          <items>
                            <AnchorPane minHeight="0.0" minWidth="0.0" prefHeight="100.0" prefWidth="160.0">
                                 <children>
                                    <Label layoutX="14.0" layoutY="14.0" text="Name:" />
                                    <Label layoutX="566.0" layoutY="49.0" text="Sperre:" />
                                    <Label layoutX="547.0" layoutY="14.0" text="Person_ID:" />
                                    <TextField fx:id="name_TextFeld_detail" layoutX="66.0" layoutY="10.0" prefHeight="25.0" prefWidth="186.0" />
                                    <Label layoutX="20.0" layoutY="49.0" text="Land:" />
                                    <TextField fx:id="land_TextFeld_detail" layoutX="66.0" layoutY="45.0" prefHeight="25.0" prefWidth="186.0" />
                                    <TextField fx:id="personId_TextFeld_detail" layoutX="620.0" layoutY="10.0" />
                                    <Label layoutX="500.0" layoutY="88.0" text="Windows Kennung:" />
                                    <TextField fx:id="sperre_TextFeld_detail" layoutX="620.0" layoutY="45.0" />
                                    <TextField fx:id="windowsKennung_TextFeld_detail" layoutX="620.0" layoutY="84.0" />
                                 </children>
                              </AnchorPane>
                            <AnchorPane minHeight="0.0" minWidth="0.0" prefHeight="100.0" prefWidth="160.0">
                                 <children>
                                    <TableView fx:id="personTable" prefHeight="709.0" prefWidth="1294.0" />
                                 </children>
                              </AnchorPane>
                          </items>
                        </SplitPane>
                     </children>
                  </AnchorPane>
            </content>
          </Tab>
        </tabs>
      </TabPane>
   </children>
</AnchorPane>

如果您需要任何帮助，请告诉我。谢谢大家。

最佳答案

在 Controller 中通过@FXML注入(inject)初始化的字段在加载相应的FXML文件时由FXMLLoader初始化。

在您的代码中，您自己创建 Controller 类的实例:

Personen_detailController detailController = new Personen_detailController();

由于在加载 FXML 时 detailController 不是由 FXMLLoader 创建的，因此 @FXML 注入(inject)的字段(例如 personTable) 不会被注入(inject)，并且将保持为空。因此出现空指针异常。 (换句话说，detailController 实际上并不是一个 Controller ，它只是一个恰好与 FMXL 文件之一的 Controller 属于同一类的对象。)

您还没有发布足够的代码来给出完整的响应，但您需要在加载 FXML 文件后从 FXMLLoader 获取 Controller :

FXMLLoader loader = new FXMLLoader(getClass().getResource("path/to/fxml/file"));
Parent root = loader.load();
// display root in UI
Person_detailController detailController = loader.getController();

然后安排将 detailController 传递给 PersonenController 实例，该实例同样是从其 FXMLLoader 检索的。

作为替代方案，请考虑使用 MVC 方法(例如 Applying MVC With JavaFx )，以便两个 Controller 都可以访问共享模型。

关于Java NullPointerException TavleView.setItem(FXCollections.observableArrayList())，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/40654589/

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