mdohr's logbook

IT retraining Week Twelve: Complex Java Concepts (Polymorphism, Inheritance) and Test Preparation

So, that was already week twelve. What did we actually do? I remember being completely confused one day and barely finishing the given task. But I also remember that everything suddenly went smoothly the next day.

This week, I wasn’t feeling well. I had constant stomach aches and didn’t have much of an appetite, so I skipped coffee and had to be careful in general. Luckily, I’m feeling better now, and I owe a lot of that to my wife, who took such good care of me and my stomach ♥

Object Orientation, Interfaces, Arrays…

Looking through my code, I can see that we continued to work on inheritance and polymorphism in class and also started using interfaces. We’ve also been using arrays more frequently for practice purposes.

This Java code demonstrates the creation and configuration of various furniture objects:

Finally, all these objects are added to a Furniture array, showcasing inheritance and polymorphism in object-oriented programming.

// SEATING furniture
Chair uglyChair = new Chair();
uglyChair.setSeats(1);
uglyChair.setArmRest(true);

Chair flimsyChair = new Chair();
flimsyChair.setSeats(1);
flimsyChair.setArmRest(false);

Chair brokenChair = new Chair();
brokenChair.setSeats(0);
brokenChair.setArmRest(false);

// COVER changeable
Sofa moldySofa = new Sofa();
moldySofa.setSeats(3);
moldySofa.setColor("Brown-ish");
moldySofa.changeCover();

Bed rancidMattress = new Bed();
rancidMattress.setWidth(90);
rancidMattress.changeCover();

// STORAGE furniture
Shelf ricketyShelf = new Shelf();
ricketyShelf.setVolume(5);
ricketyShelf.setDesigner("Destructeur Gras");

Wardrobe rottenWardrobe = new Wardrobe();
rottenWardrobe.setNumberOfShirts(20);

Furniture[] furniture = new Furniture[7];
furniture[0] = uglyChair;
furniture[1] = flimsyChair;
furniture[2] = brokenChair;
furniture[3] = moldySofa;
furniture[4] = rancidMattress;
furniture[5] = ricketyShelf;
furniture[6] = rottenWardrobe;

Polymorphism is a concept in object-oriented programming that allows objects of different classes to be treated uniformly. However, they must have a common base class or interface. This allows methods to be applied to objects of different types without needing to know their specific type.

The Test is Coming Soon

That stresses me out a bit! My last test result wasn’t bad, it was “okay,” but I’d like to do better. However, I’m not really finding time to study outside of class. Right now, I’m trying to practice with flashcards on the tram and hope that will be enough.

Some topics I think I haven’t quite mastered yet include:

Static Methods

A static method belongs to the class itself, not to individual objects of the class. It can be called without creating an instance of the class.

Access Modifiers and their UML Representation

Constructors

Example:

    public Chair(int numberOfSeats) {        
		    this.seats = numberOfSeats;    
    }

Overriding (Inheritance!)

class Animal {
    public void makeNoise() {
            System.out.println("Animal makes a noise");    
		}
}

class duck extends Animal {
    @Override
    public void make Noise() {
           System.out.println("Quack quack!");    
    }
}

Overloading

class Dog {
    public void bark() {
        System.out.println("woof!");
    }

    public void bark(int anzahl) {
        for (int i = 0; i < anzahl; i++) {
            System.out.println("Woof woof!");
        }
    }
}

I manage to get these things right in tasks, but explaining them is still hard. I’m trying not to stress myself out too much. Other Stuff

Another topic this week was internships and the associated applications. We had a fairly spontaneous application preparation session and were tasked with updating our resumes (or writing one from scratch if we didn’t have one already). So, I spent quite a bit of time on that yesterday, along with another task. The other task was to choose one of the internal companies and write a cover letter for it. This won’t be sent out yet, but at least it’s done. I had already looked into this beforehand and had an idea of where I would like to apply. So, yesterday wasn’t exactly free time.

By the way, we haven’t received our application photos yet.

#IT retraining