Practice›Java Fundamentals›Module 7. Inheritance & Polymorphism›7.5 Type checks and casting

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7.5 Type checks and casting — count the dogs

Total: 0 / 3 pts

Practice mode — check each part and get hints as you go.

Task

Fill in countDogs so that it returns how many elements of the array are really Dog objects.

The array is typed Animal[], so you cannot tell by the declared type — ask each object with instanceof. The program prints 2 and then 0.

Your solution

class Animal {
    private String name;

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

    public String getName() {
        return name;
    }

    public String describe() {
        return name + " is an animal";
    }
}

class Dog extends Animal {
    public Dog(String name) {
        super(name);
    }

    public String fetch() {
        return getName() + " fetches the ball";
    }
}

class Cat extends Animal {
    public Cat(String name) {
        super(name);
    }
}

public class Main {

    public static int countDogs(Animal[] zoo) {
        // count how many animals are really dogs

    }

    public static void main(String[] args) {
        Animal[] zoo = { new Dog("Rex"), new Cat("Kit"), new Dog("Bo") };
        System.out.println(countDogs(zoo));
        System.out.println(countDogs(new Animal[]{ new Cat("Solo") }));
    }
}

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