public class Circle

$\{$

private double radius;

$//$constructors

$//$ postcondition: the instance variable is initialized

public Circle$($double rad$)$

$\{$

radius $=$ rad;

$\}$

$//$ postcondition: the instance variable is initialized

public Circle$($int diameter$)$

$\{$

radius $=$ diameter$/2\mathrm{.}0$;

$\}$

$//$ postcondition: returns the arcLength of a circle with radius equal to this

$//$ circle's radius, according to the formula: $($PI $/180)*$ r $*$ deg,

$//$ where PI is the value of pi $(3\mathrm{.}1415...),$ r is the radius of the circle,

$//$ and deg is the angle in degrees passed as the parameter.

$//$ Use the Math class constant to represent the value of pi$.$

public double arcLength$($double degree$)$

$\{$

return $($Math$.$PI$/180)*$ radius $*$ degree;

$\}$

$//$ There may be other instance variables, constructors,

$//$ and methods that are not shown.

$\}$