JavaFX 图表自动缩放错误的低数字

Question

我正在使用 JavaFX 构建 StackedBarChart。图表将随着新数据的进入而改变。我正在使用更新图表的按钮对此进行模拟。

它大部分工作正常，但我注意到当我第一次更新图表时，对于较低的值(值小于 ~100)，Y 轴标签似乎有点偏离:

更奇怪的是，如果我第二次(或第三次、第四次...)更新图表，Y 轴的自动缩放功能就会关闭:

如果我使用较大的值(值 > ~1000)，那么自动缩放工作正常。如果我停用图表动画，那么自动缩放就可以正常工作。自动缩放在我第一次更新图表时工作正常，但之后就不行了。

这是我使用的代码，与 this 中的代码几乎相同JavaFX 教程。

import java.util.Arrays;

import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.chart.CategoryAxis;
import javafx.scene.chart.NumberAxis;
import javafx.scene.chart.StackedBarChart;
import javafx.scene.chart.XYChart;
import javafx.scene.control.Button;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class StackedBarChartSample extends Application {

    final CategoryAxis xAxis = new CategoryAxis();
    final NumberAxis yAxis = new NumberAxis();
    final StackedBarChart<String, Number> sbc = new StackedBarChart<String, Number>(xAxis, yAxis);

    @Override
    public void start(Stage stage) {

        stage.setTitle("Bar Chart Sample");

        sbc.setAnimated(true); //change this to false and autoscaling works!


        Button button = new Button("update");
        button.setOnAction(new EventHandler<ActionEvent>(){
            @Override
            public void handle(ActionEvent arg0) {
                updateChart();
            }

        });

        VBox contentPane = new VBox();
        contentPane.getChildren().addAll(sbc, button);

        Scene scene = new Scene(contentPane, 800, 600);

        stage.setScene(scene);
        stage.show();
    }


    private void updateChart(){

        int m = 1; //change this to 100 and autoscaling works!


        xAxis.setCategories(FXCollections.<String>observableArrayList());
        sbc.getData().clear();

        final XYChart.Series<String, Number> series1 = new XYChart.Series<String, Number>();
        final XYChart.Series<String, Number> series2 = new XYChart.Series<String, Number>();

        series1.setName("ABC");
        series1.getData().add(new XYChart.Data<String, Number>("one", 25*m));
        series1.getData().add(new XYChart.Data<String, Number>("two", 20*m));
        series1.getData().add(new XYChart.Data<String, Number>("three", 10*m));

        series2.setName("XYZ");
        series2.getData().add(new XYChart.Data<String, Number>("one", 25*m));
        series2.getData().add(new XYChart.Data<String, Number>("two", 20*m));
        series2.getData().add(new XYChart.Data<String, Number>("three", 10*m));


        xAxis.setCategories(FXCollections.<String>observableArrayList(Arrays.asList("one", "two", "three")));
        sbc.getData().addAll(series1, series2);
    }

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

奖励问题:动画即使有效，也会显示每个堆叠条的 2 个额外部分，这些部分在动画完成时消失。有没有办法在动画期间去掉那些多余的部分？

Answer 1

您正在使用图表、动画和可观察列表的修改方式，这似乎并不意味着要完成。好吧，我最初也是。我遇到过这样的问题，其中包括 ArrayIndexOutOfBounds 异常。简而言之:JavaFX 图表的动画非常破损，或者看起来如此。当您直接修改列表时，它似乎不可靠，因此无法使用。

我不再使用列表的动画或修改，而是在每次更改时设置列表。这两种方法中的任何一种都解决了问题。

通过使用 sbc.setData() 而不是 sbc.getData().clear() 和 sbc.getData().addAll() 来修改示例。这行得通，我。 e.动画还在:

public class StackedBarChartSample extends Application {

    final CategoryAxis xAxis = new CategoryAxis();
    final NumberAxis yAxis = new NumberAxis();
    final StackedBarChart<String, Number> sbc = new StackedBarChart<String, Number>(xAxis, yAxis);

    Random rnd = new Random();

    @Override
    public void start(Stage stage) {

        stage.setTitle("Bar Chart Sample");

        sbc.setAnimated(true); //change this to false and autoscaling works!

        Button button = new Button("update");
        button.setOnAction(new EventHandler<ActionEvent>(){
            @Override
            public void handle(ActionEvent arg0) {
                updateChart();
            }

        });

        VBox contentPane = new VBox();
        contentPane.getChildren().addAll(sbc, button);

        Scene scene = new Scene(contentPane, 800, 600);

        stage.setScene(scene);
        stage.show();
    }


    private void updateChart(){

        int m = 1; //change this to 100 and autoscaling works!

        m = rnd.nextInt(100) + 1; // just some random value to see changes in the chart

        System.out.println( "m = " + m);

        final XYChart.Series<String, Number> series1 = new XYChart.Series<String, Number>();
        final XYChart.Series<String, Number> series2 = new XYChart.Series<String, Number>();

        series1.setName("ABC");
        series1.getData().add(new XYChart.Data<String, Number>("one", 25*m));
        series1.getData().add(new XYChart.Data<String, Number>("two", 20*m));
        series1.getData().add(new XYChart.Data<String, Number>("three", 10*m));

        series2.setName("XYZ");
        series2.getData().add(new XYChart.Data<String, Number>("one", 25*m));
        series2.getData().add(new XYChart.Data<String, Number>("two", 20*m));
        series2.getData().add(new XYChart.Data<String, Number>("three", 10*m));

        sbc.setData( FXCollections.observableArrayList(series1, series2));
    }

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

我为您的 m 添加了随机性，以便查看条形中的变化。

但真正的问题是您使用图表的方式。您不应该修改列表，而应该修改列表项的数据。然后图表动画按预期工作，条形随数据上升和下降。

带有“创建”(创建新图表列表)和“修改”(修改列表数据，但不创建新列表)按钮的示例:

public class StackedBarChartSample extends Application {

    final CategoryAxis xAxis = new CategoryAxis();
    final NumberAxis yAxis = new NumberAxis();
    final StackedBarChart<String, Number> sbc = new StackedBarChart<String, Number>(xAxis, yAxis);

    Random rnd = new Random();

    final XYChart.Series<String, Number> series1 = new XYChart.Series<String, Number>();
    final XYChart.Series<String, Number> series2 = new XYChart.Series<String, Number>();

    @Override
    public void start(Stage stage) {

        stage.setTitle("Bar Chart Sample");

        sbc.setAnimated(true); //change this to false and autoscaling works!

        Button createButton = new Button("Create");
        createButton.setOnAction(new EventHandler<ActionEvent>(){
            @Override
            public void handle(ActionEvent arg0) {
                createChartData();
            }

        });

        Button modifyButton = new Button("Modify");
        modifyButton.setOnAction(new EventHandler<ActionEvent>(){
            @Override
            public void handle(ActionEvent arg0) {
                modifyChartData();
            }

        });

        VBox contentPane = new VBox();
        contentPane.getChildren().addAll(sbc, createButton, modifyButton);

        Scene scene = new Scene(contentPane, 800, 600);

        stage.setScene(scene);
        stage.show();
    }


    private void createChartData(){

        int m = 1; //change this to 100 and autoscaling works!

        m = rnd.nextInt(100) + 1; // just some random value to see changes in the chart

        System.out.println( "m = " + m);

        series1.setName("ABC");
        series1.getData().add(new XYChart.Data<String, Number>("one", 25*m));
        series1.getData().add(new XYChart.Data<String, Number>("two", 20*m));
        series1.getData().add(new XYChart.Data<String, Number>("three", 10*m));

        series2.setName("XYZ");
        series2.getData().add(new XYChart.Data<String, Number>("one", 25*m));
        series2.getData().add(new XYChart.Data<String, Number>("two", 20*m));
        series2.getData().add(new XYChart.Data<String, Number>("three", 10*m));

        sbc.setData( FXCollections.observableArrayList(series1, series2));
    }

    private void modifyChartData() {

        int m = 1; //change this to 100 and autoscaling works!

        m = rnd.nextInt(100) + 1; // just some random value to see changes in the chart

        System.out.println( "m = " + m);

        for( XYChart.Data<String,Number> data: series1.getData()) {
            data.setYValue(rnd.nextInt(30) * m);
        }

        for( XYChart.Data<String,Number> data: series2.getData()) {
            data.setYValue(rnd.nextInt(30) * m);
        }


    }

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