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.

Make a class named PirateShip which has one int field named crewSize.

Add an instance method to that class named sail which outputs

N sailors, ready to sail!

Where N is the size of the crew.

// ----------------
// CODE HERE
// ----------------

void main() {
    PirateShip ship = new PirateShip();
    ship.crewSize = 25;
    ship.sail();
}

Challenge 2.

Make a class named StringArrayView which has one String[] field named value and two methods named get and length.

get should take in an index and return the matching element of the array.

length should take no arguments and give the length of the array.

// ----------------
// CODE HERE
// ----------------

void main() {
    StringArrayView view = new StringArrayView();
    view.value = new String[] { "A", "B", "C" };

    // 3
    System.out.println(view.length());

    // A
    System.out.println(view.get(0));

    // C
    System.out.println(view.get(2));
}

Challenge 3.

Alter the VoiceActor class so that it has a method named fullName that returns their firstName followed by their lastName and separated by a space.

If their lastName is null, you should have no trailing space. If their firstName is null, you should have no leading space.

If both their firstName and lastName are null, you should return "No Name".

class VoiceActor {
    String firstName;
    String lastName;

    // -----------------
    // CODE HERE
    // -----------------
}

void main() {
    VoiceActor goku = new VoiceActor();
    goku.firstName = "Masako";
    goku.lastName = "Nozawa";

    // "Masako Nozawa"
    String gokuFullName = goku.fullName();
    System.out.println(gokuFullName);

    // "Nozawa"
    goku.firstName = null;
    gokuFullName = goku.fullName();
    System.out.println(gokuFullName);

    // "No Name"
    goku.lastName = null;
    gokuFullName = goku.fullName();
    System.out.println(gokuFullName);

    // "Horikawa"
    VoiceActor vegeta = new VoiceActor();
    vegeta.lastName = "Horikawa";
    System.out.println(vegeta.fullName());
}

Make a Rectange class which has a width field and a height field. Give it an instance method named toCharArray which gives a char[] that can be printed to display a rectangle of the given width and height.

// ------------
// CODE HERE
// ------------

void main() {
    Rectangle rectangle = new Rectangle();
    rectangle.width = 3;
    rectangle.height = 4;

    /*
        ***
        ***
        ***
        ***
    */
    char[] c = rectangle.toCharArray();
    System.out.println(c);
}

Challenge 5.

Update the definition for the Taco class so that it has a method named deluxe. This should set the taco to have beef, sour cream, cheese, and onion. Use the existing instance methods instead of directly accessing fields.

class Taco {
    boolean beef;
    boolean sourCream;
    boolean cheese;
    boolean onion;

    void addBeef() {
        this.beef = true;
    }

    void addSourCream() {
        this.sourCream = true;
    }

    void addCheese() {
        this.cheese = true;
    }

    void addOnion() {
        this.onion = true;
    }

    void deluxe() {
        // ------------
        // CODE HERE
        // ------------
    }
}

void main() {
    var taco = new Taco();
    taco.deluxe();

    System.out.println("Has Beef: " + taco.beef);
    System.out.println("Has Sour Cream: " + taco.sourCream);
    System.out.println("Has Cheese: " + taco.cheese);
    System.out.println("Has Onion: " + taco.onion);
}

Challenge 6.

Why doesn't this code function as you'd expect? Fix it by changing one line.

class Oscar {
    boolean grouchy;

    void setGrouchy(boolean grouchy) {
        grouchy = grouchy;
    }
}

void main() {
    var oscar = new Oscar();
    oscar.setGrouchy(true);
    System.out.println(oscar.grouchy);
}

Modern Java