Week 6 - Information Hiding

Original Coordinate class

public class Coordinate {
	public double x;
	public double y;

	// Make me to represent location (x,y).
	public Coordinate (double x, double y) {
		this.x = x;
		this.y = y;
	}

	// Move me by (dx,dy).
	public void move (double dx, double dy) {
		this.x = this.x + dx;
		this.y = this.y + dy;
	}

	// Rotate me around the origin by d degrees CCW.
	public void rotate (double d) {
		// Ugh: Math.sin and other ugly calls needed
	}

	// Move me 's' units away from the origin.
	public void stretch (double s) {
		// Ditto ugh!
	}
}

Modified Coordinate class

public class Coordinate {
	public double r;		// distance from origin
	public double theta;	// radians CCW from x axis

	// Make me to represent location (x,y).
	public Coordinate (double x, double y) {
		// This is now Ughish, but that's okay since
		// it doesn't need to be blazingly fast in
		// this particular application.
	}

	// Move me by (dx,dy).
	public void move (double dx, double dy) {
		// This is now Ughish too, but again that's
		// okay because of our application.
	}

	// Rotate me around the origin by d degrees CCW.
	public void rotate (double d) {
		theta = theta + d;
	}

	// Move me a factor of s away from the origin.
	public void stretch (double s) {
		r = r + s;
	}
}