public class Circle {
	// a class field
	public static final double PI=3.1459;

	// a class method
	public static double radiansToDegrees( double rads ) {
		return rads * 180 / PI;
	}

	// an instance field
	public double r;

	public Circle() {
		this(1.0);
	}

	public Circle( double r ) {
		setRadius( r );
	}

	public void setRadius(double r ) {
		this.r = r;
	}

	//two instance methods
	public double area() {
		return PI * r * r;
	}
	public double circumference () {
		return 2 * PI * r;
	}
}