Is it possible to have alternating conditions in a method in Java?

Question

So I want to create an array of polymorphic classes in Java. It's an array of animals and I want to add different kinds of animals to the array. Animal is the super class and the different kinds of animals are sub classes and I need to implement a method that adds a specific animal to the array based on the attributes but since all kinds of animals have different attributes, I don't know how to do that. I have this basic method so far and it compiles:

public void addAnimal(String name, double weight) {
        if ((numberanimals < animals.length) && (numberanimals == 0)) {
            animals[0] = new Animal(name, weight);
            numberanimals += 1;
        } else if (numberanimals < animals.length) {
            animals[numberanimals] = new Animal(name, weight);
            numberanimals += 1;
            } else {
                System.out.println("Zoo is full.");
            }
}

All animals have a name and a weight but how do I add a dog for instance based on his leash length or a shark with a boolean value that says whether he's hungry or not. Is it even possible to do that in one method like that?

Answer 1

1. Each Crocodile is an Animal.
2. Animal has guaranteed access to Animal methods and public fields.
3. You can check if an Animal is a Crocodile using animal instanceOf Crocodile
4. If it is a Crocodile, you can cast: Crocodile croco = (Crocodile)animal;.
5. You can add Crocodile to Animal[] or to List<Animal> as it is an Animal.
6. Every object is an instanceOf Object, as all classes extend Object.

Your method should be:

public void addAnimal(Animal a){
    if ((numberanimals < animals.length) && (numberanimals == 0)) {
        animals[0] = a;
        numberanimals += 1;
    } else if (numberanimals < animals.length) {
        animals[numberanimals] = a;
        numberanimals += 1;
        } else {
            System.out.println("Zoo is full.");
        }
    }
}

and then you can call it with any Animal - a Lion - addAnimal(new Lion(...)); etc.