public class Target extends GraphicsApp {
	int diameter = 10;
	int numCircles = 15;
	int diameterRed = diameter * numCircles;
	int diameterWhite = diameterRed - diameter;

	public void setup() {
		setupCanvas();
		drawCircles();
	}

	private void setupCanvas() {
		size(500, 500);
		background(Color.WHITE);
	}

	private void drawCircles() {
		Ellipse circlesRed = new Ellipse(width / 2, height / 2, diameterRed,
				diameterRed, Color.RED);
		Ellipse circlesWhite = new Ellipse(width / 2, height / 2,
				diameterWhite, diameterWhite, Color.WHITE);

		for (int i = 1; i < numCircles; i++) {
			circlesRed.draw();
			circlesRed.setSize(diameterRed - (2 * i * diameter), diameterRed
					- (2 * i * diameter));
			circlesWhite.draw();
			circlesWhite.setSize(diameterWhite - (2 * i * diameter),
					diameterWhite - (2 * i * diameter));