Java

OOP GUIDE / WORK

CIRCLE CLASS 3

Topics

• Instance methods
• toString() method

TASK – PART 1 – STARTING CODE

Copy and paste the following Circle class into your IDE to use it in this problem.

public class Circle

{

public double radius;

public Circle(double r)

{

radius = r;

}

public double area()

{

double a = Math.PI * radius * radius;

return a;

}

}

TASK – PART 2 – ADDING TO THE CIRCLE CLASS

a) Add a method that calculates and returns the circumference of the circle. You must first determine a good method name, then the method header and then implement it.

b) Add another method that calculates and returns the diameter of the circle.

c) Add a toString() method that returns a string of the form:

Circle: Radius=2

TASK – PART 3 – TESTING THE CIRCLE CLASS

Create the CircleTester class with a main method. Inside main, create a few Circle instances and call all methods to test them.