Abstract Shapes

Lab Java Intermediate 20 points

Create an abstract class Shape with abstract double area() and a concrete String describe(). Implement Circle, Rect and Triangle. Read shapes and print each description (area with 2 decimals), then the total area.

Input

n, then lines circle r, rect w h, triangle b h.

Output

n + 1 lines.

Example

Input

3
circle 1
rect 2 3
triangle 4 5

Output

circle area 3.14
rect area 6.00
triangle area 10.00
total 19.14

Sample input available Sample output available

Editor

Java

Hints

An abstract method has no body; every concrete subclass must implement it.

You can't create an object of an abstract class.

Solution explanation

The shared describe() works for every shape because each one supplies its own area().

Show solution

import java.util.Scanner;

abstract class Shape {
    abstract double area();

    abstract String name();

    String describe() {
        return String.format("%s area %.2f", name(), area());
    }
}

class Circle extends Shape {
    final double r;
    Circle(double r) { this.r = r; }
    double area() { return Math.PI * r * r; }
    String name() { return "circle"; }
}

class Rect extends Shape {
    final double w, h;
    Rect(double w, double h) { this.w = w; this.h = h; }
    double area() { return w * h; }
    String name() { return "rect"; }
}

class Triangle extends Shape {
    final double b, h;
    Triangle(double b, double h) { this.b = b; this.h = h; }
    double area() { return b * h / 2; }
    String name() { return "triangle"; }
}

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        double total = 0;
        for (int i = 0; i < n; i++) {
            String kind = sc.next();
            Shape s;
            if (kind.equals("circle")) {
                s = new Circle(sc.nextDouble());
            } else if (kind.equals("rect")) {
                s = new Rect(sc.nextDouble(), sc.nextDouble());
            } else {
                s = new Triangle(sc.nextDouble(), sc.nextDouble());
            }
            System.out.println(s.describe());
            total += s.area();
        }
        System.out.printf("total %.2f%n", total);
    }
}

Output

Answer