JavaFX |饼图类

PieChart 类是 JavaFX 的一部分。 PieChart 类用于创建饼图。图表内容由基于 PieChart 上数据集的饼图填充。默认情况下，饼图的布局设置为顺时针。 PieChart 继承 Chart 类。

类的构造函数是：

1. PieChart() ：创建一个空的饼图实例。
2. PieChart(ObservableList data) ：使用给定数据创建饼图实例。

常用方法：

Methods	Explanation
getData()	returns the data of the pie chart
getLabelLineLength()	returns the label length of the pie chart
getLabelsVisible()	Indicates whether pie slice labels are drawn or not
getStartAngle()	returns the start angle of the pie chart
isClockwise()	returns whether the pie chart is clockwise or not
setClockwise(boolean v)	sets the pie chart orientation to clockwise is true value is passed
setData(ObservableList data)	Sets the value of the property data.
setLabelLineLength(double v)	sets the label line length of pie chart .
setLabelsVisible(boolean v)	Sets the value of the property labelsVisible.
setStartAngle(double v)	sets the start angle of the the pie chart

下面的程序将说明 PieChart 类的使用：

1. 用一些指定数据创建饼图的Java程序：该程序创建饼图。将创建一个 PieChart.Data，该数据将作为可观察列表添加到饼图中。PieChart将在场景内创建，而场景又将托管在舞台内。函数setTitle()用于为舞台提供标题。然后创建一个组，并附加饼图。该组已连接到现场。最后调用show()方法显示最终结果。

   // Java program to create a pie chart 
   // with some specified data
   import javafx.application.Application;
   import javafx.scene.Scene;
   import javafx.scene.chart.PieChart;
   import javafx.scene.layout.*;
   import javafx.event.ActionEvent;
   import javafx.scene.AmbientLight;
   import javafx.scene.shape.Sphere;
   import javafx.scene.control.*;
   import javafx.stage.Stage;
   import javafx.scene.Group;
   import javafx.scene.PerspectiveCamera;
   import javafx.scene.paint.Color;
   import javafx.event.ActionEvent;
   import javafx.event.EventHandler;
   import javafx.collections.FXCollections;
      
   public class pie_chart_1 extends Application {
      
       // launch the application
       public void start(Stage stage)
       {
           // set title for the stage
           stage.setTitle("Creating Pie Chart");
      
           // piechart data
           PieChart.Data data[] = new PieChart.Data[5];
      
           // string and integer data
           String status[] = {"Correct Answer", "Wrong Answer", 
                              "Compilation Error", "Runtime Error",
                              "Others" };
                                 
           int values[] = {20, 30, 10, 4, 2};
      
           for (int i = 0; i < 5; i++) {
               data[i] = new PieChart.Data(status[i], values[i]);
           }
      
           // create a pie chart
           PieChart pie_chart = new
                   PieChart(FXCollections.observableArrayList(data));
      
           // create a Group
           Group group = new Group(pie_chart);
      
           // create a scene
           Scene scene = new Scene(group, 500, 300);
      
           // set the scene
           stage.setScene(scene);
      
           stage.show();
       }
      
      
       // Main Method
       public static void main(String args[])
       {
              
           // launch the application
           launch(args);
       }
   }
   

   输出：

   

2. Java程序创建一个带有一些指定数据的饼图，带有可见标签和定义的起始角度，并按逆时针方向排列：该程序创建一个 PieChart。将创建一个PieChart.Data作为可观察列表添加到饼图中。饼图将在场景内创建，而场景又将托管在舞台内。函数setTitle() 用于为舞台提供标题。然后创建一个组，并附加饼图。该组已连接到现场。最后调用show()方法显示最终结果。我们将使用setLabelLineLength()函数设置饼图的标签线长度，我们将分别使用setStartAngle()和setClockwise()函数设置起始角度和顺时针方向.我们可以使用 setLabelsVisible()函数使标签可见。

   // Java program to create a pie chart with
   // some specified data, with visible labels
   // and a defined start angle, and ordered 
   // in anticlockwise direction
   import javafx.application.Application;
   import javafx.scene.Scene;
   import javafx.scene.chart.PieChart;
   import javafx.scene.layout.*;
   import javafx.event.ActionEvent;
   import javafx.scene.AmbientLight;
   import javafx.scene.shape.Sphere;
   import javafx.scene.control.*;
   import javafx.stage.Stage;
   import javafx.scene.Group;
   import javafx.scene.PerspectiveCamera;
   import javafx.scene.paint.Color;
   import javafx.event.ActionEvent;
   import javafx.event.EventHandler;
   import javafx.collections.FXCollections;
      
   public class pie_chart_2 extends Application {
      
       // launch the application
       public void start(Stage stage)
       {
           // set title for the stage
           stage.setTitle("Creating Pie Chart");
      
           // piechart data
           PieChart.Data data[] = new PieChart.Data[5];
      
           // string and integer data
           String status[] = {"Correct Answer", "Wrong Answer", 
                              "Compilation Error", "Runtime Error", 
                              "Others"};
                                 
           int values[] = {20, 30, 10, 4, 2};
      
           for (int i = 0; i < 5; i++) {
               data[i] = new PieChart.Data(status[i], values[i]);
           }
      
           // create a pie chart
           PieChart pie_chart = new
                   PieChart(FXCollections.observableArrayList(data));
      
           // set line length of label
           pie_chart.setLabelLineLength(10.0f);
      
           // make labels visible
           pie_chart.setLabelsVisible(true);
      
           // set start angle
           pie_chart.setStartAngle(20.0f);
      
           // set anticlockwise
           pie_chart.setClockwise(false);
      
           // create a Group
           Group group = new Group(pie_chart);
      
           // create a scene
           Scene scene = new Scene(group, 500, 500);
      
           // set the scene
           stage.setScene(scene);
      
           stage.show();
       }
      
       // Main Method
       public static void main(String args[])
       {
              
           // launch the application
           launch(args);
       }
   }
   

   输出：

   

注意：上述程序可能无法在在线 IDE 中运行。请使用离线编译器。

参考： https://docs.oracle.com/javase/8/javafx/api/javafx/scene/chart/PieChart.html