Java 14 Protected,Polymorphism, Inheritance

ANIMAL.JAVA

// Animal will act as a Super class for other Animals
public class Animal {
    
    private String name = "Animal";
    public String favFood = "Food";
    
    // You use protected when you want to allow subclasses
    // To be able to access methods or fields
    // If you would have used private their would be no
    // way for subclasses to call this method
    // This is a final method which means it can't be overwritten
    
    protected final void changeName(String newName){
        
        // this is a reference to the object you're creating
        
        this.name = newName;
        
    }
    
    protected final String getName(){
        
        return this.name;
        
    }
    
    public void eatStuff(){
        
        System.out.println("Yum " + favFood);
        
    }
    
    public void walkAround(){
        
        System.out.println(this.name + " walks around");
        
    }
    
    public Animal(){
        
    }
    
    public Animal(String name, String favFood){
        
        this.changeName(name);
        this.favFood = favFood;
        
    }
    
}

CAT.JAVA

// Cat is a Subclass of Animal
// You create subclasses with the extends keyword
// Now Cat has all the Methods and Fields that Animal defined
// This is known as inheritance because Cat inherits all
// the methods and fields defined in Animal

public class Cat extends Animal{
    
    // You can add new fields to the subclass
    public String favToy = "Yarn";
    
    // You can add new methods
    public void playWith(){
        
        System.out.println("Yeah " + favToy);
        
    }
    
    // Here I overrode the Animal walkAround method
    public void walkAround(){
        
        // this refers to a specific object created of type Cat
        
        System.out.println(this.getName() + " stalks around and then sleeps");
        
    }
    
    public String getToy(){
        
        return this.favToy;
        
    }
    
    public Cat(){
        
    }
    
    public Cat(String name, String favFood, String favToy){
        
        // super calls the constructor for the super class Animal
        
        super(name, favFood);
        
        // We set the favToy value in Cat because it doesn't 
        // exist in the Animal class
        
        this.favToy = favToy;
        
    }
    
}

LESSONFOURTEEN.JAVA

public class LessonFourteen{
    
public static void main(String[] args){
        
        // I create a Animal object named genericAnimal
    
        Animal genericAnimal = new Animal();
        System.out.println(genericAnimal.getName());
        System.out.println(genericAnimal.favFood);
        
    
        // I create a Cat class like any other
        Cat morris = new Cat("Morris", "Tuna", "Rubber Mouse");
        
        // Print out the name, favFood and favToy
        System.out.println(morris.getName());
        System.out.println(morris.favFood);
        System.out.println(morris.favToy);
        
        // You can also create classes based on the super class
        
        Animal tabby = new Cat("Tabby", "Salmon", "Ball");
        
        // You pass objects like any other field
        acceptAnimal(tabby);
        
    }
    
    public static void acceptAnimal(Animal randAnimal){
        
        // Gets the name and favFood for the Animal passed
        System.out.println(randAnimal.getName());
        System.out.println(randAnimal.favFood);
        
        // This is Polymorphism
        // The interpreter automatically figures out what type
        // of Animal it's dealing with and checks to make sure
        // if methods were overwritten that they are called 
        // instead
        randAnimal.walkAround();
        
        // The interpreter won't find anything that doesn't 
        // originally exist in the Animal class however
        // System.out.println(randAnimal.favToy); Throws an ERROR
        
        // If you want access to fields or methods only found
        // in the Cat class you have to cast the object to
        // that specific class first
        Cat tempCat = (Cat) randAnimal;
        
        System.out.println(tempCat.favToy);
        
        // You could also cast the object directly like this
        System.out.println(((Cat) randAnimal).favToy);
        
        // You can use instanceof to check what type of object
        // you have. This results in a positive for Animal 
        // and for Cat
        if (randAnimal instanceof Cat)
        {
            System.out.println(randAnimal.getName() + " is a Cat");
        }
        
    }
    
}