Java

OOP GUIDE / WORK

CIRCLE CLASS 3 SOLUTIONS

TASK – PART 1 – STARTING CODE

No solution required.

TASK – PART 2 – ADDING TO THE CIRCLE CLASS

Here is my solution with the code that was provided in Part 1 displayed in green:

public class Circle

{

public double radius;

public Circle(double r)

{

radius = r;

}

public double area()

{

double a = Math.PI * radius * radius;

return a;

}

public double circumference()

{

double c = 2 * Math.PI * radius;

return c;

}

public double diameter()

{

double d = radius * 2;

return d;

}

public String toString()

{

return "Circle: Radius=" + radius;

}

}

Note: The area(), circumference() and diameter() methods could all easily have been coded as a single line instead of two lines.

TASK – PART 3 – TESTING THE CIRCLE CLASS

Here is my solution:

public class CircleTester

{

public static void main(String[] args)

{

Circle c1 = new Circle(5);

System.out.println(c1.area());

System.out.println(c1.circumference());

System.out.println(c1.diameter());

System.out.println(c1); //calling toString()

Circle c2 = new Circle(1);

System.out.println(c2.area());

System.out.println(c2.circumference());

System.out.println(c2.diameter());

System.out.println(c2); //calling toString()

}

}

The above will output the following:

78.53981633974483

31.41592653589793

10.0

Circle: Radius=5.0

3.141592653589793

6.283185307179586

2.0

Circle: Radius=1.0