java - JavaFX PieChart 的问题

Question

我有一个带有复选框和 2 个动画图表的应用程序:饼图和条形图。 当选中复选框时，将触发向图表添加新数据的方法。 当复选框未被选中时，会触发从图表中删除数据的方法。

当我点击复选框的速度不是很快时，一切正常。但是，如果我在动画完成之前再次单击复选框，我会收到以下错误:

 java.lang.NullPointerException
at javafx.scene.chart.PieChart$7.handle(PieChart.java:370)
at javafx.scene.chart.PieChart$7.handle(PieChart.java:367)
at   com.sun.scenario.animation.shared.TimelineClipCore.visitKeyFrame(TimelineClipCore.java:217)
at com.sun.scenario.animation.shared.TimelineClipCore.playTo(TimelineClipCore.java:158)
at javafx.animation.Timeline.impl_playTo(Timeline.java:182)
at com.sun.scenario.animation.shared.SingleLoopClipEnvelope.timePulse(SingleLoopClipEnvelope.java:119)
at javafx.animation.Animation.impl_timePulse(Animation.java:953)
at com.sun.scenario.animation.shared.AnimationPulseReceiver.timePulse(AnimationPulseReceiver.java:117)
at com.sun.scenario.animation.AbstractMasterTimer.timePulseImpl(AbstractMasterTimer.java:366)
at com.sun.scenario.animation.AbstractMasterTimer$MainLoop.run(AbstractMasterTimer.java:289)
at com.sun.javafx.tk.quantum.QuantumToolkit.pulse(QuantumToolkit.java:454)
at com.sun.javafx.tk.quantum.QuantumToolkit$8.run(QuantumToolkit.java:325)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.access$100(WinApplication.java:29)
at com.sun.glass.ui.win.WinApplication$2$1.run(WinApplication.java:62)
at java.lang.Thread.run(Unknown Source)

这一切只发生在 PieChart 上。条形图工作正常。

这是 checkBox onAction 事件的方法:

  public void OnCheckFired(ActionEvent event) {
    Boolean b = checkBox.isSelected();
    chart.modifyChart(currentChart,b);
}

Thant 是用于修改饼图的代码:

@Override
public void makeModifications(Chart chart, Boolean b) {
    PieChart pie = (PieChart) chart;
    ObservableList<PieChart.Data> pieChartData = pie.getData();
    pieChartData = modify(b, pieChartData);
    pie.setData(pieChartData);
}

private ObservableList<Data> modify(Boolean b, ObservableList<PieChart.Data> pieChartData)  {
    if (b) {
        pieChartData.add(new PieChart.Data("newValue", 34));
    } else {
        int size = pieChartData.size() - 1;
        pieChartData.remove(size);
    }
    return pieChartData;
}

Answer 1

我已经修改了 Sergey 在他的回答中提到的错误问题所附的代码。将按钮替换为在动画播放时禁用的复选框以及动画完成时额外半秒的复选框。每次选择更改时它都会以这种方式运行。

public class Tdesst extends Application {

    private void init(Stage primaryStage) {
        VBox root = new VBox();
        Scene scene = new Scene(root);
        primaryStage.setScene(scene);
        final ObservableList<PieChart.Data> pieChartData = FXCollections.observableArrayList(
                new PieChart.Data("Sun", 20),
                new PieChart.Data("IBM", 12),
                new PieChart.Data("HP", 25),
                new PieChart.Data("Dell", 22),
                new PieChart.Data("Apple", 30));
        final PieChart chart = new PieChart(pieChartData);

        final CheckBox chkbox = new CheckBox("add/remove data");

        final Timeline animation = new Timeline(
                new KeyFrame(Duration.seconds(.5),
                new EventHandler<ActionEvent>() {
                    @Override public void handle(ActionEvent actionEvent) {
                        chkbox.setDisable(false);
                    }
                }));
        animation.setCycleCount(1);

        chkbox.selectedProperty().addListener(new ChangeListener<Boolean>() {

            @Override
            public void changed(ObservableValue<? extends Boolean> arg0, Boolean oldVal, Boolean newVal) {
                chkbox.setDisable(true);
                if (newVal) {
                    pieChartData.add(new PieChart.Data("newValue", 34));
                } else {
                    pieChartData.remove(pieChartData.size() - 1);
                }
                animation.play();
            }
        });

        root.getChildren().add(chart);
        root.getChildren().add(chkbox);
    }

    @Override
    public void start(Stage primaryStage) throws Exception {
        init(primaryStage);
        primaryStage.show();
        primaryStage.setTitle(VersionInfo.getRuntimeVersion());
    }

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

或者你可以完全禁用动画

chart.setAnimated(false);