Area Calculation: Add, Subtract, Intersect, Exclusive Or

[Java Tip]

import java.awt.Container;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.geom.Area;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;

import javax.swing.ButtonGroup;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;

public class AreaTest {
  public static void main(String[] args) {
    JFrame frame = new AreaTestFrame();
    frame.show();
  }
}

class AreaTestFrame extends JFrame implements ActionListener {
  public AreaTestFrame() {
    setTitle("AreaTest");
    setSize(400, 400);
    addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    });

    Container contentPane = getContentPane();
    canvas = new AreaPanel();
    contentPane.add(canvas, "Center");

    JPanel buttonPanel = new JPanel();
    ButtonGroup group = new ButtonGroup();

    addButton = new JRadioButton("Add", true);
    buttonPanel.add(addButton);
    group.add(addButton);
    addButton.addActionListener(this);

    subtractButton = new JRadioButton("Subtract", false);
    buttonPanel.add(subtractButton);
    group.add(subtractButton);
    subtractButton.addActionListener(this);

    intersectButton = new JRadioButton("Intersect", false);
    buttonPanel.add(intersectButton);
    group.add(intersectButton);
    intersectButton.addActionListener(this);

    exclusiveOrButton = new JRadioButton("Exclusive Or", false);
    buttonPanel.add(exclusiveOrButton);
    group.add(exclusiveOrButton);
    exclusiveOrButton.addActionListener(this);

    contentPane.add(buttonPanel, "North");
  }

  public void actionPerformed(ActionEvent event) {
    Object source = event.getSource();
    if (source == addButton)
      canvas.addAreas();
    else if (source == subtractButton)
      canvas.subtractAreas();
    else if (source == intersectButton)
      canvas.intersectAreas();
    else if (source == exclusiveOrButton)
      canvas.exclusiveOrAreas();
  }

  private AreaPanel canvas;

  private JRadioButton addButton;

  private JRadioButton subtractButton;

  private JRadioButton intersectButton;

  private JRadioButton exclusiveOrButton;
}

class AreaPanel extends JPanel {
  public AreaPanel() {
    area1 = new Area(new Ellipse2D.Double(100, 100, 150, 100));
    area2 = new Area(new Rectangle2D.Double(150, 150, 150, 100));
    addAreas();
  }

  public void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D) g;
    g2.draw(area1);
    g2.draw(area2);
    g2.fill(area);
  }

  public void addAreas() {
    area = new Area();
    area.add(area1);
    area.add(area2);
    repaint();
  }

  public void subtractAreas() {
    area = new Area();
    area.add(area1);
    area.subtract(area2);
    repaint();
  }

  public void intersectAreas() {
    area = new Area();
    area.add(area1);
    area.intersect(area2);
    repaint();
  }

  public void exclusiveOrAreas() {
    area = new Area();
    area.add(area1);
    area.exclusiveOr(area2);
    repaint();
  }

  private Area area;

  private Area area1;

  private Area area2;
}