final的练习

public class finalExercise {
    public static void main(String[] args) {
        System.out.println(new Circle(5.0).area());
    }
}

class Circle{
    private double ridus;
    private final double PI;

    public Circle(double ridus) {
        this.ridus = ridus;
//        PI = 3.14
    }
    {
        PI = 3.14;
    }

    public double area(){
        return ridus * ridus * PI;
    }

    @Override
    public String toString() {
        return "Circle{" +
                "ridus=" + ridus +
                ", PI=" + PI +
                '}';
    }
}