object_oriented.java

public class Square implements Shape {
    private Point topLeft;
    private double side;
    
    public double area() {
        return side*side;
    }
}

public class Rectangle implements Shape {
    private Point topLeft;
    private double height;
    private double width;
    
    public double area() {
        return height * width;
    }
}

public class Circle implements Shape {
    private Point center;
    private double radius;
    public final double PI = 3.141592653589793;
    
    public double area() {
        return PI * radius * radius;
    }
}

interface Shape {
    double area();
}