Practice›Java Fundamentals›Module 8. Interfaces & Abstract Classes›8.1 Interfaces

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8.1 Interfaces — total area

Total: 0 / 3 pts

Practice mode — check each part and get hints as you go.

Task

Fill in totalArea so that it returns the sum of the areas of all the shapes.

The array is typed Shape[] — the interface — yet each element runs its own area(). The program prints 9.14.

Your solution

interface Shape {
    double area();
    String name();
}

class Circle implements Shape {
    private double r;

    public Circle(double r) {
        this.r = r;
    }

    public double area() {
        return 3.14 * r * r;
    }

    public String name() {
        return "Circle";
    }
}

class Rect implements Shape {
    private double w;
    private double h;

    public Rect(double w, double h) {
        this.w = w;
        this.h = h;
    }

    public double area() {
        return w * h;
    }

    public String name() {
        return "Rect";
    }
}

public class Main {

    public static double totalArea(Shape[] shapes) {
        // add up the area of every shape

    }

    public static void main(String[] args) {
        Shape[] shapes = {new Circle(1), new Rect(2, 3)};
        System.out.println(totalArea(shapes));
    }
}

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