Object Oriented Programming

Let's review some core concepts about OOP

@kenji_lozano

Kenji Lozano

Senior Software Developer, Truextend

Angular, React and Java

Javascript Lover

Sucre, Bolivia

Cochabamba

Spring, .NET

WHY OOP?!

Keep in mind... ;)

Based on your interviews we got the following:

 

  • Most of you have a "REGULAR" OOP Knowledge
  • We expect a "GOOD" to "EXCELLENT" knowledge

So...
What is OOP?

Paradigm

Four Pillars of Object Oriented Programming

Encapsulation

Encapsulation

... is the mechanism of hiding of data implementation by restricting access to public methods through Access Modifiers

class ExampleClass {
    private int integerValue;
    private String stringValue;

    public int getIntegerValue(){
        return integerValue;
    }

    public String getStringValue(){
        return stringValue;
    }

    public void setIntegerValue(int newValue){
        integerValue = newValue;
    }

    public void setStringValue(String newValue){
        stringValue = newValue;
    }

}

Encapsulation

Abstraction

Abstraction

... is the act of removing characteristics from something in order to reduce it to a set of essential functions or characteristics

Abstraction

Security

Servers

Transactions

Nobody cares about it!

Abstraction

What to have an abstraction to draw and get area of a Shape

Abstraction

public interface Shape{
  public void draw();
  public double getArea();
}

Abstraction

public class Circle implements Shape{ 
  private double radius;
  
  public Circle(double r){ 
  	this.radius = r; 
  }
  
  void draw(){ 
  	System.out.println("Drawing Circle"); 
  }
  
  public double getArea(){ 
  	return Math.PI*this.radius*this.radius; 
  }
  
  public double getRadius(){
  	return this.radius; 
  } 
}

Abstraction

public class Test{ 
  public static void main (String args[]){
    Shape c = new Circle(8);
    c.draw(); 
    System.out.println("Area=" + c.getArea());
  }
}

Pro-Tip

Encapsulation vs Abstraction

Encapsulation is realization of your desired abstraction.

Abstraction is more about hiding the implementation details. Encapsulation is about wrapping the implementation (code) and the data it manipulates (variables) within the same class

Inheritance

Inheritance

... expresses “is-a” and/or “has-a” relationship between two objects

Inheritance

class Teacher {
	String designation = "Teacher";
	String collegeName = "Beginnersbook";
	void does(){
    	System.out.println("Teaching");
	}
}

public class PhysicsTeacher extends Teacher{
	String mainSubject = "Physics";
}
public static void main(String args[]){
	PhysicsTeacher obj = new PhysicsTeacher();
	System.out.println(obj.collegeName);
	System.out.println(obj.designation);
	System.out.println(obj.mainSubject);
	obj.does();
}
Beginnersbook
Teacher
Physics
Teaching

Polymorphism

Polymorphism

... is the ability of an object to take on many forms.

 

... is one of the OOPs feature that allows us to perform a single action in different ways

Polymorphism

public class Animal{
   ...
   public void sound(){
      System.out.println("Animal is making a sound");
   }
}
public class Horse extends Animal{
...
    @Override
    public void sound(){
        System.out.println("Neigh");
    }
}
public class Cat extends Animal{
...
    @Override
    public void sound(){
        System.out.println("Meow");
    }
}
    public static void main(String args[]){
    	Animal obj = new Horse();
    	obj.sound();
    }
Neight

Don't Forget The Four OOP Pillars

Encapsulation

Abstraction

Inheritance

Polymorphism

So, this was just a quick talk about the most important OOP concepts

Challenge Time!

Event Ticketing App

Want to have you modeling an app that let us buy tickets for any event.

You could have the use case of Stadium "Felix Capriles"

Could be just a Class Diagram or whatever you want to show us your modeling skills

Consider that you could have more than 1 types of tickets

You MUST use the Four Pillars of Object Oriented Programming

You MUST consider the Scalability, Adaptability and Flexibility

Event Ticketing App

We expect something like this:

https://stackify.com/oop-concept-abstraction/

Event Ticketing App

If we (Kenji) like your solution, will send you a gift (usually food)

The organizer (Kenji) reserves the rights to have a winning solution

Thank You!

Hope you enjoyed this talk!

Resources

https://www.edureka.co/blog/java-abstraction/

https://stackify.com/oop-concept-abstraction/

https://richardeng.medium.com/a-simple-explanation-of-oop-46a156581214

https://medium.com/learn-how-to-program/chapter-3-what-is-object-oriented-programming-d0a6ec0a7615

https://medium.com/from-the-scratch/oop-everything-you-need-to-know-about-object-oriented-programming-aee3c18e281b

https://medium.com/swlh/oop-concept-in-javascript-119f03b0a134

https://www.javacodemonk.com/what-are-four-principles-of-oop-how-aggregation-is-different-than-composition-5b534baf