Challenges

Remember the rules for this are

• Try to use only the information given up to this point in this book.
• Try not to give up until you've given it a solid attempt

Challenge 1.

Create an interface named TabbyCat. It should extend the provided Cat interface and provide a lounge method along with a default implementation of that method.

interface Cat {
    void purr();
}

// CODE HERE

class Garfield implements TabbyCat {
    @Override
    public void purr() {
        IO.println("mmmm lasagna");
    }
}

class Main {
    void main() {
        TabbyCat c = new Garfield();
        // Should come in via a default method.
        c.lounge();
    }
}

Challenge 2.

Add a static field to the Cat interface which indicates the healthy amount of lasagna for a cat to consume.¹

interface Cat {
    void purr();
}

class Main {
    void main() {
        // 0
        IO.println(Cat.HEALTHY_AMOUNT_OF_LASAGNA);
    }
}

Challenge 3.

Put a static method on the Cat interface named garfield" which returns an instance of TabbyCat`.

public interface Cat {
    // CODE HERE
}

public interface TabbyCat extends Cat {
    // CODE FROM PREVIOUS CHALLENGES
}

class Garfield implements TabbyCat {
    @Override
    public void purr() {
        IO.println("mmmm lasagna");
    }
}

public class Main {
    void main() {
        TabbyCat tc = Cat.garfield();
        tc.lounge();
    }
}

Note that this gives you a way to expose a Garfield instance to other packages, even if the Garfield class itself is non-public.²