Dragon Fractal in Java

DragonCurve.java

package dragon;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;

import javax.imageio.ImageIO;

public final class DragonCurve {

	private BufferedImage img = null;
	private int IMG_WIDTH;
	private int IMG_HEIGHT;

	private GraphicsEnvironment ge = null;
	private GraphicsDevice gd = null;
	private GraphicsConfiguration gc = null;

	public DragonCurve() {
		IMG_WIDTH = 1400;
		IMG_HEIGHT = 1400;

		ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
		gd = ge.getDefaultScreenDevice();
		gc = gd.getDefaultConfiguration();

	}

	private void createDragonFractal() {
		Graphics g = null;
		Graphics2D g2d = (Graphics2D) g;

		img = gc.createCompatibleImage(IMG_WIDTH, IMG_HEIGHT);
		g2d = img.createGraphics();
		g2d.setColor(Color.black);
		g2d.fillRect(0, 0, IMG_WIDTH, IMG_HEIGHT);
		g2d.setColor(Color.red);
		dragonRecur(300, 500, 1000, 1100, 20, g2d);
		g2d.drawImage(img, 0, 0, null);
		g2d.dispose();
		writeImage();

	}

	private void writeImage() {
		File file = new File("pic.png");
		try {
			file.createNewFile();
			OutputStream out = new FileOutputStream(file);
			ImageIO.write(img, "png", out);
			out.close();
		} catch (IOException e) {
			e.printStackTrace();
		}

	}

	private void dragonRecur(int x1, int y1, int x2, int y2, int k,
			Graphics2D g2d) {
		if (k > 0) {
			int xn = (x1 + x2) / 2 + (y2 - y1) / 2;
			int yn = (y1 + y2) / 2 - (x2 - x1) / 2;
			dragonRecur(x2, y2, xn, yn, k - 1, g2d);
			dragonRecur(x1, y1, xn, yn, k - 1, g2d);
		} else {
			g2d.drawLine(x1, y1, x2, y2);
		}
	}

	public static void main(String... strings) {
		new DragonCurve().createDragonFractal();
	}

}