exercise11_13.java

Introduction to java programming 一书中所有编程练习部分的源码

// Exercise11_13.java: Draw a fan with four blazes
import java.awt.*;
import javax.swing.*;

public class Exercise11_13 extends JFrame {
  public static void main(String[] args) {
    JFrame frame = new Exercise11_13();
    frame.setSize(300, 300);
    frame.setTitle("Exercise11_13");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);
  }

  public Exercise11_13() {
    setTitle("Drawing a Fan");
    Container container = getContentPane();
    container.setLayout(new GridLayout(2, 2, 5, 5));
    container.add(new FanPanel());
    container.add(new FanPanel());
    container.add(new FanPanel());
    container.add(new FanPanel());
  }
}

class FanPanel extends JPanel {
  private int xCenter, yCenter;
  private int fanRadius, bladeLength;
  private int angle = 100;

  protected void paintComponent(Graphics g) {
    super.paintComponent(g);

    // Set fan radius, and center
    fanRadius = (int)(Math.min(getSize().width,
    getSize().height)*0.9*0.5);
    xCenter = (getSize().width)/2;
    yCenter = (getSize().height)/2;
    bladeLength = (int)(fanRadius*0.9);

    // Draw circle
    g.setColor(Color.black);
    g.drawOval(xCenter - fanRadius,yCenter - fanRadius,
    2*fanRadius, 2*fanRadius);

    // Draw four blades
    drawBlade(g, angle);
    drawBlade(g, angle+90);
    drawBlade(g, angle+180);
    drawBlade(g, angle+270);
  }

  private void drawBlade(Graphics g, int angle) {
    g.setColor(Color.red);
    g.fillArc(xCenter-bladeLength, yCenter-bladeLength,
    2*bladeLength, 2*bladeLength, angle, 30);
  }

  public Dimension getPreferredSize() {
    return new Dimension(200, 200);
  }
}