如何用嵌入JavaFx applet在Swing中更新饼图-空点异常

Question

我正在完成学校的最后一项编程任务，想在我的java应用程序中添加一个小功能糖果，在JavaFX中以动态饼图的形式。

使用NetBeans7.2rc2，我从模板中创建了一个Swing/JavaFX混合应用程序。我扩展了JPanelClass来创建一个shell，我的主要应用程序可以用它来访问FX特性。然而，我面临的问题是，虽然图表的初始化进行得很顺利，但当我试图更新broked的东西时，它会生成一个空指针异常。我相信下面是相关的代码：

实例化：

public class PieChartJFxPanel extends JApplet {

  private static final int JFXPANEL_WIDTH_INT = 500;
  private static final int JFXPANEL_HEIGHT_INT = 500;

    StackPane root = new StackPane();
    PieChart athleteChart;
    ObservableList<PieChart.Data> pieChartData =FXCollections.observableArrayList();
    private static JFXPanel fxContainer;
    private int fAthletes=0;
    private int rAthletes=0;

   public PieChartJFxPanel(int totalAthletes,int finishedAthletes){
    super();
    fAthletes=finishedAthletes;
    rAthletes=totalAthletes-fAthletes;
}

@Override
public void init() {
    fxContainer = new JFXPanel();
    fxContainer.setPreferredSize(new Dimension(JFXPANEL_WIDTH_INT, JFXPANEL_HEIGHT_INT));                    
    add(fxContainer, BorderLayout.CENTER);
    // create JavaFX scene
    Platform.runLater(new Runnable() {
        @Override
        public void run() {
            createScene();
        }
    });
}

private void createScene() {     
    pieChartData.add(new PieChart.Data("Finished",fAthletes));
    pieChartData.add(new PieChart.Data("Outstanding",rAthletes));               
    athleteChart=new PieChart();     
    athleteChart.setLegendVisible(false);
   athleteChart.setTitle("Race Status");
   //athleteChart.setAnimated(true);       
    athleteChart.setData(pieChartData);               

    root.getChildren().add(athleteChart);
    fxContainer.setScene(new Scene(root));        
    //


}

public void setData(int total, int in){
    final  ObservableList<PieChart.Data> pieChartDat=FXCollections.observableArrayList();
    pieChartDat.add(new PieChart.Data("Finished",fAthletes));
    pieChartDat.add(new PieChart.Data("Outstanding",rAthletes));  
    athleteChart.setData(pieChartDat);                
}

Exception in thread "main" java.lang.NullPointerException
     at piechartjpanel.PieChartJFxPanel.setData(PieChartJFxPanel.java:95)
     at piechartjpanel.AthleteIOChart.setAthletes(AthleteIOChart.java:62)
     at piechartjpanel.Test.setter(Test.java:34)
     at piechartjpanel.Test.main(Test.java:48)

任何帮助都很感激：）提前感谢

Answer 1

您从不初始化AtheleteChart

athleteChart.setData（pieChartDat）；

AthleteChart在调用时为null，并且始终为null。