テーブルビューのJavaFXアプリケーションスレッド」java.lang.NullPointerExceptionが

Question

私のプログラムは、製品情報を格納するデータベースをシミュレートしようとしている。

私は私が理解しない事がまだ彼らのいるテーブルビューを使用する方法を学習しようとしています。私にはテーブル私は複数のアイテムを選択してそれらのアイテムで何かをしたいと思っています既に完了しているもの

行1を選択すると1つの問題があります& 2を右クリックし、右クリックしてProductNameをクリックすると、JavaFXアプリケーションスレッド「java.lang.NullPointerException」が表示されます。

なぜそれがそれをしているのか分かりません。お手伝いができればどうぞ。ありがとうございました。 私の英語は申し訳ありません。

package TestTableView; 

import javafx.application.Application; 
import javafx.collections.FXCollections; 
import javafx.collections.ObservableList; 
import javafx.scene.Scene; 
import javafx.scene.control.ContextMenu; 
import javafx.scene.control.MenuItem; 
import javafx.scene.control.SelectionMode; 
import javafx.scene.control.TableColumn; 
import javafx.scene.control.TableView; 
import javafx.scene.control.cell.PropertyValueFactory; 
import javafx.scene.layout.VBox; 
import javafx.scene.web.WebEngine; 
import javafx.scene.web.WebView; 
import javafx.stage.Stage; 
import static javafx.application.Application.launch; 


public class TestTableView extends Application { 
    private Stage Listwindow; 
    private TableView<Product> table; 
    private String name; 
    private ObservableList<Product> itemSelected; 
    private WebView browser = new WebView(); 
    private WebEngine webEngine = browser.getEngine(); 

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

@Override 
    public void start(Stage primaryStage){  
     //Load UnitTable 
     Listwindow = primaryStage; 
     Listwindow.setTitle("Product Table"); 

     createTable(); 
     createContextMenu(); 

     VBox vBox = new VBox(); 
     vBox.getChildren().addAll(table); 
     Scene scene = new Scene(vBox); 
     Listwindow.setScene(scene); 
     Listwindow.show(); 
    } 

    public void createContextMenu(){ 
     //Multiple selection 
     table.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE); 


     itemSelected = table.getSelectionModel().getSelectedItems(); 

     //ContextMenu 
     ContextMenu contextMenu = new ContextMenu(); 

     //menu items 
     MenuItem item1 = new MenuItem("ProductName"); 

     //Add item to context menu 
     contextMenu.getItems().addAll(item1); 

     //set context menu to table 
     table.setContextMenu(contextMenu); 


     item1.setOnAction(e -> getProductName());   
    } 

    public void getProductName(){ 
     for(int x = 0; x < itemSelected.size(); x++){ 
      name = itemSelected.get(x).getName(); 

      //do Something -> Name 
     }  
     table.getSelectionModel().clearSelection(); 
    }  

    public void createTable(){ 

     TableColumn<Product, String> nameCol = new TableColumn<>("Name"); 
     nameCol.setMinWidth(200); 
     nameCol.setCellValueFactory(new PropertyValueFactory<>("name")); 

      TableColumn<Product, Double> priceCol = new TableColumn<>("Price"); 
      priceCol.setMinWidth(200); 
      priceCol.setCellValueFactory(new PropertyValueFactory<>("price")); 

      TableColumn<Product, Integer> quantityCol = new TableColumn<>("Quantity"); 
      quantityCol.setMinWidth(200); 
      quantityCol.setCellValueFactory(new PropertyValueFactory<>("quantity")); 

      table = new TableView<>(); 
      table.setItems(getUnits()); 
      table.getColumns().addAll(nameCol,priceCol,quantityCol);   
     } 

     public ObservableList<Product> getUnits(){ 

      ObservableList<Product> unit = FXCollections.observableArrayList();  
      unit.add(new Product("Toilet",90.00,100)); 
      unit.add(new Product("Chair",200.00,200)); 
      unit.add(new Product("Avengers DVD",15.00,50)); 
      return unit; 
     } 
    } 

製品クラス

package TestTableView; 

    public class Product { 
     private String name; 
     private int quantity; 
     private double price; 

     Product(){ 
      this.name = ""; 
      this.price = 0; 
      this.quantity = 0; 
     } 
     Product(String Name, double price, int quantity) { 
      this.name = name; 
      this.quantity = quantity; 
      this.price = price; 
     } 

     public String getName() { 
      return name; 
     } 

     public void setName(String name) { 
      this.name = name; 
     } 

     public int getQuantity() { 
      return quantity; 
     } 

     public void setQuantity(int quantity) { 
      this.quantity = quantity; 
     } 

     public double getPrice() { 
      return price; 
     } 

     public void setPrice(double price) { 
      this.price = price; 
     } 

    } 

//

Exception in thread "JavaFX Application Thread" java.lang.NullPointerException 
     at TestTableView.TestTableView.getProductName(TestTableView.java:73) 
     at TestTableView.TestTableView.lambda$createContextMenu$0(TestTableView.java:68) 
     at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86) 
     at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238) 
     at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191) 
     at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58) 
     at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) 
     at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74) 
     at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49) 
     at javafx.event.Event.fireEvent(Event.java:198) 
     at javafx.scene.control.MenuItem.fire(MenuItem.java:462) 
     at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer.doSelect(ContextMenuContent.java:1405) 
     at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer.lambda$createChildren$343(ContextMenuContent.java:1358) 
     at com.sun.javafx.event.CompositeEventHandler$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.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) 

Answer 1

BadVegan固定ループ前に問題をitemSelected.sorted（）を添加示唆されるよう

public void getProductName(){ 
    itemSelected.sorted(); 
    for(int x = 0; x < itemSelected.size(); x++){ 
     name = itemSelected.get(x).getName(); 

     //do Something -> Name 
    }  
    table.getSelectionModel().clearSelection(); 
}  

Answer 2

これは、あなたがテーブルに がリフレッシュ取得していない値を変更するとき 使用ゲッターが引き起こすProduct class.Don'tの正しい実装である必要があります：[編集]あなたの質問インクルードする

import javafx.beans.property.DoubleProperty; 
import javafx.beans.property.IntegerProperty; 
import javafx.beans.property.SimpleDoubleProperty; 
import javafx.beans.property.SimpleIntegerProperty; 
import javafx.beans.property.SimpleStringProperty; 
import javafx.beans.property.StringProperty; 

public class Product { 

    private StringProperty name; 
    private DoubleProperty price; 
    private IntegerProperty quantity; 

    /** 
    * Constructor 
    */ 
    protected Product() { 
     name = new SimpleStringProperty(""); 
     price = new SimpleDoubleProperty(0.0); 
     quantity = new SimpleIntegerProperty(0); 

    } 

    /** 
    * Constructor 
    * 
    * @param name 
    * @param price 
    * @param quantity 
    */ 
    protected Product(String name, double price, int quantity) { 
     this.name = new SimpleStringProperty(name); 
     this.price = new SimpleDoubleProperty(price); 
     this.quantity = new SimpleIntegerProperty(quantity); 
    } 

    public StringProperty nameProperty() { 
     return name; 
    } 

    public DoubleProperty priceProperty() { 
     return price; 
    } 

    public IntegerProperty quantityProperty() { 
     return quantity; 
    } 

    public void setName(String name) { 
     this.name.set(name); 
    } 

    public void setPrice(double price) { 
     this.price.set(price); 
    } 

    public void setQuantity(int quantity) { 
     this.quantity.set(quantity); 
    } 

}