调用从 main 方法扩展另一个 class 的 class

Question

所以我有一个 class 可以绘制条形图。我从这里得到代码：

https://docs.oracle.com/javafx/2/charts/bar-chart.htm

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.chart.BarChart;
import javafx.scene.chart.CategoryAxis;
import javafx.scene.chart.NumberAxis;
import javafx.scene.chart.XYChart;
import javafx.stage.Stage;

public class BarChartSample extends Application {
final static String austria = "Austria";
final static String brazil = "Brazil";
final static String france = "France";
final static String italy = "Italy";
final static String usa = "USA";

@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));
    series1.getData().add(new XYChart.Data(brazil, 20148.82));
    series1.getData().add(new XYChart.Data(france, 10000));
    series1.getData().add(new XYChart.Data(italy, 35407.15));
    series1.getData().add(new XYChart.Data(usa, 12000));      

    XYChart.Series series2 = new XYChart.Series();
    series2.setName("2004");
    series2.getData().add(new XYChart.Data(austria, 57401.85));
    series2.getData().add(new XYChart.Data(brazil, 41941.19));
    series2.getData().add(new XYChart.Data(france, 45263.37));
    series2.getData().add(new XYChart.Data(italy, 117320.16));
    series2.getData().add(new XYChart.Data(usa, 14845.27));  

    XYChart.Series series3 = new XYChart.Series();
    series3.setName("2005");
    series3.getData().add(new XYChart.Data(austria, 45000.65));
    series3.getData().add(new XYChart.Data(brazil, 44835.76));
    series3.getData().add(new XYChart.Data(france, 18722.18));
    series3.getData().add(new XYChart.Data(italy, 17557.31));
    series3.getData().add(new XYChart.Data(usa, 92633.68));  

    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);
}

}

但问题是我想在另一个 class 中从我的主要方法调用此 BarChartSample class。例如，我有一个名为 BookRecommender 的 class 并且有一个 main 方法。我希望能够设置参数，例如标题、xlabel、ylabel 以及此 BarChartSample class 的值。但是我无法从我的 Recommender class 运行启动 BarChartSample class 的方法。

Answer 1

这是一个 JavaFX 应用程序，因此您不会直接从另一个 class 调用此 class。您需要将此 class 的功能封装在 class 中，然后从 JavaFX 应用程序中调用它。

例如您可以使用 subclass Scene 来创建特定的 BarChartScene，然后在构造函数或方法 setData([data you wish to pass]) 中传递您需要的数据。或者您可以创建一个 BarChartSceneFactory class，它将 return 一个 Scene 对象。

例如 SceneFactory.java

import javafx.scene.Scene;
import javafx.scene.chart.BarChart;
import javafx.scene.chart.CategoryAxis;
import javafx.scene.chart.NumberAxis;
import javafx.scene.chart.XYChart;

public abstract class SceneFactory {
    private static final String AUSTRIA = "Austria";
    private static final String BRAZIL = "Brazil";
    private static final String FRANCE = "France";
    private static final String ITALY = "Italy";
    private static final String USA = "USA";

    public static Scene getBarChartScene() {
        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));
        series1.getData().add(new XYChart.Data(BRAZIL, 20148.82));
        series1.getData().add(new XYChart.Data(FRANCE, 10000));
        series1.getData().add(new XYChart.Data(ITALY, 35407.15));
        series1.getData().add(new XYChart.Data(USA, 12000));      

        XYChart.Series series2 = new XYChart.Series();
        series2.setName("2004");
        series2.getData().add(new XYChart.Data(AUSTRIA, 57401.85));
        series2.getData().add(new XYChart.Data(BRAZIL, 41941.19));
        series2.getData().add(new XYChart.Data(FRANCE, 45263.37));
        series2.getData().add(new XYChart.Data(ITALY, 117320.16));
        series2.getData().add(new XYChart.Data(USA, 14845.27));  

        XYChart.Series series3 = new XYChart.Series();
        series3.setName("2005");
        series3.getData().add(new XYChart.Data(AUSTRIA, 45000.65));
        series3.getData().add(new XYChart.Data(BRAZIL, 44835.76));
        series3.getData().add(new XYChart.Data(FRANCE, 18722.18));
        series3.getData().add(new XYChart.Data(ITALY, 17557.31));
        series3.getData().add(new XYChart.Data(USA, 92633.68));  

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

MainApp.java

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class MainApp extends Application {
    @Override
    public void start(Stage stage) {
        Scene scene = SceneFactory.getBarChartScene();
        stage.setScene(scene);
        stage.setTitle("Bar Chart Sample");
        stage.show();
    }
}

然后您可以在主示例应用程序中简单地调用 SceneFactory.getBarChartScene() 来获取场景对象并将其设置在舞台上。

如果您希望显示自己的自定义数据，请将其作为参数传递给 getScene 方法，例如Map<Integer, Map<String, Double>> chartData 其中第一个整数包含年份，映射到国家名称到值的映射。

或者你可以子class场景，也可以这样做，例如

public class BarChartScene extends Scene {
    public BarChartScene([pass some data in here]) {
        // Build your scene based on the data passed in the constructor.
    }
}

Answer 2

您的主要 class 是否也扩展了应用程序？如果是这样，我会修改你的代码，这样它就不会扩展应用程序。您可以添加方法来修改您需要的任何数据。您甚至可以将所需的代码复制并粘贴到您的应用程序中。

调用从 main 方法扩展另一个 class 的 class

Call a class that extends another class from main method

java

inheritance

overriding

bar-chart