Main.java

import java.util.*;

class Shape {
    private String name;

    public Shape(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public double getArea() {
        return 0;
    }
}

class Rectangle extends Shape {
    private double area;
    private double width;
    private double height;

    public Rectangle(String name, double width, double height) {
        super(name);
        this.area = width * height;
        this.width = width;
        this.height = height;
    }

    public double getArea() {
        return area;
    }

    public double getWidth() {
        return width;
    }

    public double getHeight() {
        return height;
    }
}

class Triangle extends Shape {
    private double base, height, area;

    public Triangle(String name, double base, double height) {
        super(name);
        this.base = base;
        this.height = height;
        this.area = 0.5 * base * height;
    }

    public double getArea() {
        return area;
    }

    public double getBase() {
        return base;
    }

    public double getHeight() {
        return height;
    }
}

public class Main {
    public static double findTotalArea(ArrayList<Shape> shapes) {
        double total = 0;
        for (Shape shape : shapes) {
            total += shape.getArea();
        }
        return total;
    }

    public static void main(String[] args) {
        ArrayList<Shape> shapes = new ArrayList<Shape>();
        shapes.add(new Rectangle("r1", 3, 8));
        shapes.add(new Triangle("t1", 3, 2));

        System.out.println(findTotalArea(shapes));
    }
}