条形图中的中心条

Question

我修改了 Oracle 网站的条形图示例，将每个系列的条形图减少到 1 个。不幸的是，条形图没有在刻度线上方居中。

有谁知道如何让条形图在刻度线上方水平居中？

代码如下：

public class BarChartDemo extends Application {
    final static String austria = "Austria";
    final static String brazil = "Brazil";
    final static String france = "France";

    @Override
    public void start(Stage stage) {
        stage.setTitle("Bar Chart Sample");
        final CategoryAxis xAxis = new CategoryAxis();
        final NumberAxis yAxis = new NumberAxis();
        final BarChart<String, Number> bc = new BarChart<String, Number>(xAxis, yAxis);
        bc.setTitle("Country Summary");

        xAxis.setLabel("Country");
        yAxis.setLabel("Value");

        XYChart.Series series1 = new XYChart.Series();
        series1.setName("2003");
        series1.getData().add(new XYChart.Data(austria, 25601.34));

        XYChart.Series series2 = new XYChart.Series();
        series2.setName("2004");
        series2.getData().add(new XYChart.Data(brazil, 41941.19));

        XYChart.Series series3 = new XYChart.Series();
        series3.setName("2005");
        series3.getData().add(new XYChart.Data(france, 18722.18));

        Scene scene = new Scene(bc, 800, 600);
        bc.getData().addAll(series1, series2, series3);
        stage.setScene(scene);
        stage.show();
    }

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

这是它的样子：

非常感谢！

Answer 1

问题

您的条形图的问题在于您添加了 3 个系列，但每个系列中只有一个独特的国家/地区。条形图固有地为其他 2 个系列留下 space。

解决方案

实现此目的的正确方法是使用 one XYChart.Series，然后为每个条形图添加颜色。这是一个示例应用程序，它执行相同的操作。

public class BarChartDemo extends Application {
    final static String austria = "Austria";
    final static String brazil = "Brazil";
    final static String france = "France";

    @Override
    public void start(Stage stage) {
        stage.setTitle("Bar Chart Sample");
        final CategoryAxis xAxis = new CategoryAxis();
        final NumberAxis yAxis = new NumberAxis();
        final BarChart<String, Number> bc = new BarChart<String, Number>(xAxis, yAxis);
        bc.setTitle("Country Summary");

        xAxis.setLabel("Country");
        yAxis.setLabel("Value");

        XYChart.Series series1 = new XYChart.Series();
        series1.setName("2003");
        final XYChart.Data<String, Number> dataAustria = new XYChart.Data(austria, 25601.34);
        final XYChart.Data<String, Number> dataBrazil = new XYChart.Data(brazil, 41941.19);
        final XYChart.Data<String, Number> dataFrance = new XYChart.Data(france, 35000.19);
        series1.getData().add(dataAustria);
        series1.getData().add(dataBrazil);
        series1.getData().add(dataFrance);
        Scene scene = new Scene(bc, 800, 600);
        bc.getData().addAll(series1);
        stage.setScene(scene);
        stage.show();
        dataAustria.getNode().setStyle("-fx-bar-fill: CHART_COLOR_1;");
        dataBrazil.getNode().setStyle("-fx-bar-fill: CHART_COLOR_2;");
        dataFrance.getNode().setStyle("-fx-bar-fill: CHART_COLOR_3;");
    }

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

输出符合您的要求：

注意：节点显示在舞台上后，您需要对其应用样式。或者，您可以使用 xyChartData.nodeProperty().addListener() 并将样式应用到其中。

dataAustria.nodeProperty().addListener((ov, oldNode, newNode) -> {
    if(null != newNode) {
        newNode.setStyle("-fx-bar-fill: red;");
    }
});

条形图中的中心条

Center bars in a bar chart

javafx

bar-chart