8. Abstract Classes: Partial Implementation

Scenario

An abstract class provides some common behavior but forces subclasses to implement specific details.

Code Block

abstract class Shape {
    String color;
    Shape(String color) { this.color = color; }
    
    void describe() { System.out.println("A " + color + " shape"); }
    abstract double area(); // Must be implemented by subclasses
}

class Circle extends Shape {
    double radius;
    Circle(String color, double radius) {
        super(color);
        this.radius = radius;
    }
    
    @Override
    double area() { return Math.PI * radius * radius; }
}

public class Main {
    public static void main(String[] args) {
        Shape s = new Circle("Red", 5);
        s.describe();
        System.out.println("Area: " + Math.round(s.area()));
    }
}

Take Your Shot

Predicted Output

Type exactly what you think will be printed in the console.