INTRO TO OBJECT-ORIENTED PROGRAMMING (OOP)

📘 INTRO TO OBJECT-ORIENTED PROGRAMMING (OOP)

“This part is important kasi ito ‘yung foundation ng topic.”

🔹 What is a Programming Paradigm?

  • A programming paradigm is basically a style or pattern kung paano ka magsusulat ng code.

  • Think of it as “coding philosophy”.

The 3 Main Paradigms:

Paradigm

Focus

Example Languages

Procedural

Step-by-step instructions

C, C++, Pascal

Functional

Functions & expressions

Haskell, Scala

Object-Oriented (OOP)

Objects + real-world modeling

Java, Python

👉 In short: Paradigm = how you think while coding.

🔁 PROCEDURAL vs FUNCTIONAL vs OOP

🧩 Procedural Programming

  • Code runs step by step

  • Uses variables + procedures (functions)

  • Very linear (top-down)

📌 Real-life analogy:
Parang recipe — gawin mo muna step 1, then step 2, then step 3.

Key Points:

  • Uses procedures/functions

  • Data is not well protected

  • Harder to maintain for large programs

🧮 Functional Programming

  • Focuses on functions and expressions

  • Avoids loops like for, while

  • Functions are first-class citizens

📌 Real-life analogy:
Parang math formulas — input → output, walang pakialam sa process.

🧱 Object-Oriented Programming (OOP)

  • Focuses on objects that represent real-world things

  • Combines data + actions

📌 Real-life analogy:
Parang LEGO blocks — bawat object may sariling role, pero puwedeng pagsamahin.

OOP Involves:

  • Creating classes (blueprints)

  • Creating objects (actual instances)

  • Making apps that use those objects

🆚 Procedural vs OOP (IMPORTANT TABLE)

Procedural

OOP

Focus on procedures

Focus on data

Data not secured

Data secured

Top-down approach

Bottom-up approach

No real-world model

Models real-world entities

Functions-based

Object-based

🧠 Mnemonic:
P = Process, OOP = Object

🌟 ADVANTAGES OF OOP

Why programmers love OOP 💙

  • ✅ Reusable code (less copy-paste)

  • ✅ More secure data (encapsulation)

  • ✅ Less complex for big systems

  • ✅ Easy maintenance

  • ✅ Faster development time

👉 In short: Mas clean, mas organized, mas scalable.

🧠 CORE OOP CONCEPTS (SUPER IMPORTANT)

🏗 Class

  • A blueprint or template

  • Defines:

    • Attributes (properties)

    • Methods (actions)

📌 Example:
Class = Recipe
Object = Actual food

🧍 Object

  • A real instance of a class

  • Has:

    • Data members (characteristics)

    • Function members (actions)

📱 Smartphone Example:

  • Data: color, weight, price

  • Functions: call(), camera(), record()

👉 Rule: Objects = nouns

⚙ Method

  • A function inside a class

  • Defines what an object can do

👉 Rule: Methods = verbs

🔗 Class–Object–Method Relationship

Class

Object (Data)

Method (Action)

Automobile

Model, Color

Drive(), Brake()

Dog

Name, Age

Walk(), Eat()

🧠 Mnemonic:
COM = Class → Object → Method

🎭 FOUR PILLARS OF OOP

1⃣ Data Abstraction

  • Show only important features

  • Hide unnecessary details

📌 Example:
You use Bluetooth, but you don’t care how it works inside.

👉 User sees what they need — not the chaos behind it.

2⃣ Data Encapsulation

  • Wrapping data + methods in one class

  • Protects data from outside access

📌 Real-life analogy:
ATM — you can withdraw money, but you can’t touch the bank’s system.

3⃣ Inheritance

  • Child class inherits from parent class

📌 Example:

Employee (Parent)

├── Manager

├── Supervisor

└── Clerk

👉 Child gets shared traits + sariling features.

4⃣ Polymorphism

  • Same action, different behavior

Types:

  • Operator Overloading

    + → add numbers OR join strings

  • Function Overloading

    Same method name, different parameters

🧠 Mnemonic:

Poly = many | morphism = forms

🛠 METHODS IN JAVA

main() Method

  • Entry point ng program

  • Always runs first

Method Header Breakdown:

Keyword

Meaning

public

Accessible everywhere

static

No object needed

void

No return value

main

Method name

Why Use Methods?

  • Makes code cleaner

  • Reusable

  • Easier to understand

👉 If your main() looks messy, you’re doing it wrong.

🧱 CLASSES & OBJECTS (JAVA-SPECIFIC)

Data Fields

  • Variables inside a class

  • Can be:

    • static → shared

    • non-static → unique per object

Access Modifiers

Modifier

Access

private

Class only

public

Everywhere

👉 Private = security

Getter & Setter Methods

  • Getter → get value

  • Setter → set/change value

📌 Naming rule:

  • getEmpNum()

  • setEmpNum()

🧪 OBJECT INSTANTIATION

Creating Objects:

Employee emp = new Employee();

What happens?

  • new allocates memory

  • Constructor initializes object

👉 Object = reference to memory

🧠 FINAL QUICK RECAP (CHEAT MODE)

🧩 OOP Pillars

A-E-I-P

  • Abstraction

  • Encapsulation

  • Inheritance

  • Polymorphism

🏗 Structure

Class → Object → Method

🧍 Rules to Remember

  • Objects = nouns

  • Methods = verbs

  • Private = protected data

  • main() runs first

🧠 MEMORY TRICKS (EXAM-SAVER 💯)

  • Blueprint = Class

  • Instance = Object

  • Action = Method

  • Hide details = Abstraction

  • Protect data = Encapsulation

  • Parent → Child = Inheritance

  • Same name, diff behavior = Polymorphism