public class Circle implements Shape { private final double radius; public Circle(double radius) { this.radius = radius; } @Override public double area() { return Math.PI*radius*radius; } @Override public double diameter() { return 2*radius; } @Override public double perimeter() { return 2*Math.PI*radius; } @Override public String toString() { return String.format("Circle(%s)", radius); } public double getRadius() { return radius; } }