a. Create a class named Circle with fields named radius, diameter, and area.

Include a constructor that sets the radius to 1 and calculates the other two values. Also

include methods named setRadius()and getRadius(). The setRadius() method

not only sets the radius, it also calculates the other two values. (The diameter of a circle

is twice the radius, and the area of a circle is pi multiplied by the square of the radius.

Use the Math class PI constant for this calculation.) Save the class as Circle.java.

b. Create a class named TestCircle whose main() method declares several Circle

objects. Using the setRadius() method, assign one Circle a small radius value,

and assign another a larger radius value. Do not assign a value to the radius of the

third circle; instead, retain the value assigned at construction. Display all the

values for all the Circle objects. Save the application as TestCircle.java.