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Saturday, 24 December 2016

Chapter 14 Exercise 13, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

14.13 (Display a pie chart)
Write a program that uses a pie chart to display the percentages
of the overall grade represented by projects, quizzes, midterm exams,
and the final exam, as shown in Figure 14.46c. Suppose that projects take
20 percent and are displayed in red, quizzes take 10 percent and are
displayed in blue, midterm exams take 30 percent and are displayed in green,
and the final exam takes 40 percent and is displayed in orange. Use the Arc
class to display the pies. Interested readers may explore the JavaFX PieChart
class for further study.


import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Arc;
import javafx.scene.shape.ArcType;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Shape;
import javafx.scene.text.Text;
import javafx.stage.Stage;

import java.util.ArrayList;

public class Exercise_13 extends Application {

    private static double[] percent = new double[]{0.20, 0.10, 0.30, 0.40};
    private static String[] titles = new String[] {
            "project -- " + String.format("%d%s", (int)(100 * percent[0]), "%"),
            "quizzes -- " + String.format("%d%s", (int)(100 * percent[1]), "%"),
            "midterm -- " + String.format("%d%s", (int)(100 * percent[2]), "%"),
            "final -- "+ String.format("%d%s", (int)(100 * percent[3]), "%")
    };
    private static Color[] colors = new Color[]{Color.RED, Color.BLUE, Color.GREEN, Color.ORANGE};

    private static double RADIUS = 100;
    private static double CENTER_X = 200;
    private static double CENTER_Y = 200;

    @Override
    public void start(Stage primaryStage) {

        Pane pane = new Pane();
        ArrayList<Shape> shapes = new ArrayList<>();

        Circle c = new Circle(CENTER_X, CENTER_Y, RADIUS, Color.TRANSPARENT);
        c.setStroke(Color.BLACK);
        shapes.add(c);
        double angle = 0;
        for (int i = 0; i < titles.length; i++) {

            double length = percent[i] * 100 * 3.6;
            Arc arc = new Arc(CENTER_X, CENTER_Y, RADIUS, RADIUS, angle, length);
            arc.setFill(colors[i]);
            arc.setType(ArcType.ROUND);
            shapes.add(arc);

            double x = CENTER_X + RADIUS * Math.cos(Math.toRadians(angle * -1 - (length / 2)));
            double y = CENTER_Y + RADIUS * Math.sin(Math.toRadians(angle * -1 - (length / 2)));
            if (y > CENTER_Y) {
                y -= RADIUS / 2;
                x -= RADIUS / 2;
            }
            Text text = new Text(x, y, titles[i]);
            shapes.add(text);

            angle += length;
        }

        pane.getChildren().addAll(shapes);
        primaryStage.setScene(new Scene(pane, 400, 400));
        primaryStage.setTitle("Pie Chart");
        primaryStage.show();
    }

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

}

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