Object-Oriented Programming (OOP): Classes and Objects in C++ and Java — Step-by-Step from Chip to Network Level Thinking

L. P. Harisha Lakshan Warnakulasuriya(Bsc in CS(OUSL)).

Bachelor of Bio Science in Computer Science.

📚 Table of Contents (1–30 Topics)

Part 1: Foundations of Object-Oriented Programming

1. Introduction to Object-Oriented Programming (OOP)
2. The Chip-Level Thinking: How OOP Starts Inside Hardware
3. Bits, Bytes, and Instructions: Laying the Groundwork for OOP
4. Memory Management and Object Storage at Low Level
5. From Chip to Compiler: How Code is Translated into Machine Instructions

Part 2: Core Concepts of Classes and Objects

1. Fundamentals of Classes and Objects
2. Classes and Objects in C++: A Low-Level and High-Level Perspective
3. Classes and Objects in Java: A Low-Level and High-Level Perspective
4. Real-world Code Examples: Practical Implementation in C++ and Java
5. Memory Allocation Strategies in C++ vs Java

Part 3: Deep Dive into Object-Oriented Programming Principles

1. The Four Pillars of OOP: Inheritance, Polymorphism, Encapsulation, and Abstraction
2. Understanding Compile-Time vs Runtime Behavior
3. Exception Handling Inside Classes in C++ and Java
4. How Objects Behave in Network Communication

Part 4: Advanced Concepts in Object Handling

1. Serialization and Object Transmission in Java and C++
2. Distributed Object Systems: RMI, CORBA, and Beyond
3. Network-level Class Applications: Microservices and APIs

Part 5: Detailed Mechanisms of OOP

1. Deep Dive into Constructors and Destructors in C++ and Java
2. Static Members and Static Blocks: Shared Class Data
3. Advanced Polymorphism: Virtual Functions and Overriding
4. Inner Classes and Nested Classes: Structures within Structures
5. Interfaces and Abstract Classes: Building Contracts in OOP

Part 6: Modern Memory and Resource Management

1. Smart Pointers in C++: Managing Dynamic Memory Safely
2. Lambda Functions Inside Classes: Functional Programming within OOP

Part 7: Object Behavior, Cloning, and Multithreading

1. Object Cloning and Copy Constructors: Duplicating Object States
2. Multithreading with Objects: Parallelism in C++ and Java

Part 8: Design Patterns and Real-World Application

1. Common OOP Design Patterns: Singleton, Factory, Observer, Decorator
2. The Future of Object-Oriented Programming: Trends and Innovations

Part 9: Conclusion

1. From Chip to Cloud: The Epic Journey of Object-Oriented Programming
2. Final Thoughts: Mastering OOP from Hardware to Distributed Systems

1. Introduction to Object-Oriented Programming

Object-Oriented Programming (OOP) is a paradigm where code is organized around "objects" — real-world entities that have both data (attributes) and behavior (methods). In simple terms:

• An object is like a noun (person, place, or thing).
• A class defines a blueprint for these objects.

Languages like C++ and Java implement OOP to make coding modular, maintainable, and scalable.

2. The Chip-Level Thinking: How OOP Starts Inside Hardware

At the most basic level — inside the chip (CPU):

• Every operation you write is broken down into binary instructions (1s and 0s).
• Classes and objects are just patterns of memory addresses and instruction flows.

🔹 Example: When you declare a class, internally the compiler maps memory to hold variables and compiles methods into instructions ready to run.

👉 Therefore, OOP starts at the transistor level where instructions manipulate memory registers, cache, and RAM.

3. Bit, Byte, Instruction: Laying the Groundwork for OOP

• Bit: Smallest unit of information (0 or 1)
• Byte: Group of 8 bits (e.g., 01001101)
• Instruction: Machine commands processed by CPU (e.g., MOV, ADD, CALL).

When you create an object:

✅ The attributes are stored in memory addresses. ✅ The methods are turned into function calls in assembly language.

4. Memory Management and Object Storage at Low Level

When an object is created:

• In C++, it can live on the stack (for small, short-lived objects) or heap (using new operator).
• In Java, all objects are created on the heap using new, and managed by Garbage Collector.

Memory layout typically looks like:

| Object Header | Fields | Padding | Method Table (VTable - for polymorphism) |
        

🔹 Think of objects as "compact blocks" of data with a pointer to methods.

5. From Chip to Compiler: How Code is Translated

• Your high-level C++/Java code ➡ Compiler ➡ Assembly ➡ Machine Code ➡ Chip executes.
• Compilers allocate memory layout for classes.
• Linkers connect function calls.
• Loaders place objects in memory at runtime.

6. Fundamentals of Classes and Objects

Class: Blueprint of an object (defines properties + behavior). Object: An instance created from a class.

Syntax:

// C++ Example
class Car {
public:
    string brand;
    int speed;
    void accelerate() {
        speed += 10;
    }
};
        

// Java Example
public class Car {
    String brand;
    int speed;
    void accelerate() {
        speed += 10;
    }
}
        

7. Classes and Objects in C++: Low-Level and High-Level View

🔹 C++ Objects:

• Memory is explicitly managed.
• Constructors and destructors are compiled into machine instructions.
• Code is closer to hardware performance.

🔹 Creating an Object:

Car myCar;
myCar.brand = "Toyota";
myCar.speed = 50;
myCar.accelerate();
        

🛠 Internally:

• myCar occupies stack memory.
• Function accelerate() is a jump instruction.

8. Classes and Objects in Java: Low-Level and High-Level View

🔹 Java Objects:

• Memory is managed automatically.
• All classes inherit from Object class implicitly.
• Runs inside JVM (Java Virtual Machine).

🔹 Creating an Object:

Car myCar = new Car();
myCar.brand = "Honda";
myCar.speed = 60;
myCar.accelerate();
        

🛠 Internally:

• Object created on heap.
• JVM manages method dispatch via virtual tables.

9. Real-world Code Examples

C++ Example: Bank Account Class

#include<iostream>
using namespace std;

class BankAccount {
public:
    string owner;
    double balance;

    BankAccount(string own, double bal) {
        owner = own;
        balance = bal;
    }

    void deposit(double amount) {
        balance += amount;
    }

    void display() {
        cout << "Owner: " << owner << ", Balance: $" << balance << endl;
    }
};

int main() {
    BankAccount account1("Alice", 500.00);
    account1.deposit(250.00);
    account1.display();
}
        

Java Example: Student Management Class

public class Student {
    String name;
    int id;
    double gpa;

    public Student(String name, int id, double gpa) {
        this.name = name;
        this.id = id;
        this.gpa = gpa;
    }

    public void printDetails() {
        System.out.println("Name: " + name + ", ID: " + id + ", GPA: " + gpa);
    }

    public static void main(String[] args) {
        Student stu1 = new Student("John", 12345, 3.8);
        stu1.printDetails();
    }
}
        

10. Memory Allocation in C++ vs Java

Aspect C++ Java Memory Allocation Manual (stack/heap) Automatic (heap) Garbage Collection Manual (delete) Automatic (GC) Performance Faster (no VM overhead) Slower (VM overhead)

11. Inheritance, Polymorphism, Encapsulation, Abstraction

✅ Inheritance Allows classes to inherit features from another class.

✅ Polymorphism One interface, many implementations.

✅ Encapsulation Data hiding + protecting variables.

✅ Abstraction Showing only essential features.

🔹 Example (Java):

class Animal {
    void sound() {
        System.out.println("Animal sound");
    }
}

class Dog extends Animal {
    void sound() {
        System.out.println("Bark");
    }
}
        

12. Compile-time vs Runtime Behavior

Aspect Compile-Time Run-Time Syntax checking Performed Not performed Memory Layout Prepared partially Allocated dynamically Method Binding Early (Static) binding Late (Dynamic) binding (polymorphism)

13. Exception Handling inside Classes

// C++ Exception Handling
class Division {
public:
    double divide(double a, double b) {
        if (b == 0) throw "Division by zero error!";
        return a / b;
    }
};
        

// Java Exception Handling
class Division {
    public double divide(double a, double b) throws ArithmeticException {
        if (b == 0) throw new ArithmeticException("Division by zero error!");
        return a / b;
    }
}
        

14. How Objects Behave in Network Communication

In distributed systems:

• Objects can be serialized into a format (binary, JSON, XML).
• Then sent over TCP/IP or HTTP to another machine.
• Deserialized into an object at the receiver end.

15. Serialization and Object Transmission in Java and C++

✅ Java Serialization:

import java.io.Serializable;

public class Employee implements Serializable {
    String name;
    int id;
}
        

✅ C++ Serialization:

// Typically manual: write object's bytes to file/socket
ofstream outfile("employee.dat", ios::binary);
outfile.write((char*)&employee, sizeof(employee));
        

16. Distributed Object Systems

• CORBA (Common Object Request Broker Architecture) for C++.
• RMI (Remote Method Invocation) for Java.

They allow objects to communicate across networks like local method calls.

17. Network-Level Class Applications: Microservices, APIs

In modern systems:

• Classes are used to model API responses.
• Objects are serialized into JSON.
• Microservices (e.g., Spring Boot in Java) use classes as DTOs (Data Transfer Objects).

🔹 Example (Java + REST API):

@RestController
public class ProductController {

    @GetMapping("/product")
    public Product getProduct() {
        return new Product("Laptop", 1200);
    }
}
        

18. Conclusion: The Journey from a Transistor to the Internet

Object-Oriented Programming (OOP) connects the hardware level (bits, memory, instructions) all the way up to networked software systems (microservices, APIs).

From the moment a class is compiled, objects are created, and methods are executed, hardware, software, and network all work together to create the seamless experiences we use today.

Thus, understanding OOP — not just from the code perspective, but from the chip to the network — makes you a much better engineer, architect, and innovator.

19. Deep Dive into Constructors and Destructors (C++ vs Java)

What is a Constructor?

A constructor is a special method that initializes an object when it is created.

Feature C++ Java Name Same as class name Same as class name Parameters Can be overloaded Can be overloaded Default Provided Yes (if none defined manually) Yes (if none defined manually)

🔥 C++ Example: Constructor and Destructor

#include<iostream>
using namespace std;

class Car {
public:
    string brand;
    int speed;

    // Constructor
    Car(string b, int s) {
        brand = b;
        speed = s;
    }

    // Destructor
    ~Car() {
        cout << "Destructor called for " << brand << endl;
    }

    void display() {
        cout << brand << " running at " << speed << " km/h" << endl;
    }
};

int main() {
    Car myCar("BMW", 120);
    myCar.display();
}
        

🔥 Java Example: Constructor (No Destructor)

public class Car {
    String brand;
    int speed;

    // Constructor
    Car(String brand, int speed) {
        this.brand = brand;
        this.speed = speed;
    }

    void display() {
        System.out.println(brand + " running at " + speed + " km/h");
    }

    public static void main(String[] args) {
        Car myCar = new Car("Audi", 130);
        myCar.display();
    }
}
        

☑️ Java does not have destructors — memory is cleaned by Garbage Collector.

Hardware Level View (Chip Thinking)

At low level:

• Constructor execution = memory allocation + initialization instructions.
• Destructor (C++) = resource cleanup (memory deallocation, file handles, sockets).
• In Java, finalizers existed (finalize()), but now deprecated.

20. Static Members and Static Blocks

What is a Static Member?

• Static member belongs to the class, not to instances.
• Shared among all objects.

🔥 C++ Example: Static Members

#include<iostream>
using namespace std;

class Counter {
public:
    static int count;

    Counter() {
        count++;
    }
};

int Counter::count = 0; // initialize static member

int main() {
    Counter c1, c2, c3;
    cout << "Total objects: " << Counter::count << endl;
}
        

🔥 Java Example: Static Members

public class Counter {
    static int count = 0;

    Counter() {
        count++;
    }

    public static void main(String[] args) {
        Counter c1 = new Counter();
        Counter c2 = new Counter();
        Counter c3 = new Counter();
        System.out.println("Total objects: " + Counter.count);
    }
}
        

Static Blocks

• Java allows a static block to initialize static variables.

class Example {
    static int number;

    static {
        number = 100; // runs once when class is loaded
    }
}
        

At Chip Level: Static variables are stored in the global data segment of the program's memory.

21. Advanced Polymorphism: Virtual Functions and Overriding

What is Virtual Function (C++)?

• Declared with virtual keyword.
• Supports runtime polymorphism.
• Enables dynamic dispatch using vtable (virtual method table).

🔥 C++ Example: Virtual Function

#include<iostream>
using namespace std;

class Base {
public:
    virtual void display() {
        cout << "Display Base" << endl;
    }
};

class Derived : public Base {
public:
    void display() override {
        cout << "Display Derived" << endl;
    }
};

int main() {
    Base *bptr;
    Derived d;
    bptr = &d;
    bptr->display(); // calls Derived's display
}
        

Java’s Polymorphism (Override)

All non-final methods in Java are virtual by default.

🔥 Java Example: Method Overriding

class Base {
    void display() {
        System.out.println("Display Base");
    }
}

class Derived extends Base {
    @Override
    void display() {
        System.out.println("Display Derived");
    }
}

public class Test {
    public static void main(String[] args) {
        Base obj = new Derived();
        obj.display(); // calls Derived's display
    }
}
        

At Hardware Level:

• VTable lookup happens dynamically.
• Jump instruction points to correct method address.

22. Inner Classes and Nested Classes

C++ Nested Classes

class Outer {
public:
    class Inner {
    public:
        void show() {
            cout << "Inner Class" << endl;
        }
    };
};
        

Java Nested and Inner Classes

public class Outer {
    class Inner {
        void show() {
            System.out.println("Inner Class");
        }
    }
}
        

At the chip level: Nested classes are treated as another memory unit compiled separately.

23. Interfaces and Abstract Classes

Abstract Class (C++ and Java)

• Cannot instantiate.
• Can have both implemented and unimplemented methods.

🔥 Java Example: Abstract Class

abstract class Shape {
    abstract void draw();
}

class Circle extends Shape {
    void draw() {
        System.out.println("Drawing Circle");
    }
}
        

Interface (Only in Java)

• Pure abstraction.
• All methods are implicitly abstract and public.

interface Drawable {
    void draw();
}

class Rectangle implements Drawable {
    public void draw() {
        System.out.println("Drawing Rectangle");
    }
}
        

24. Smart Pointers in C++

What is Smart Pointer?

• C++11 introduced smart pointers for automatic memory management.

Types:

Type Purpose unique_ptr Sole ownership shared_ptr Reference counted shared ownership weak_ptr Non-owning reference

🔥 Example: unique_ptr

#include <iostream>
#include <memory>
using namespace std;

class Demo {
public:
    Demo() { cout << "Constructor" << endl; }
    ~Demo() { cout << "Destructor" << endl; }
};

int main() {
    unique_ptr<Demo> ptr = make_unique<Demo>();
}
        

25. Lambda Functions inside Classes (Modern C++ and Java)

Lambda Expression

Anonymous functions you can define inline.

🔥 C++ Lambda Example

#include<iostream>
using namespace std;

class Math {
public:
    void calculate() {
        auto add = [](int a, int b) { return a + b; };
        cout << "Sum: " << add(5, 3) << endl;
    }
};

int main() {
    Math m;
    m.calculate();
}
        

🔥 Java Lambda Example

(Java 8 onwards)

import java.util.function.*;

public class Math {
    public static void main(String[] args) {
        BiFunction<Integer, Integer, Integer> add = (a, b) -> a + b;
        System.out.println("Sum: " + add.apply(5, 3));
    }
}
        

26. Object Cloning and Copy Constructors

C++ Copy Constructor

class Box {
public:
    int length;

    Box(int l) {
        length = l;
    }

    Box(const Box &b) {
        length = b.length;
    }
};
        

Java Object Cloning

class Box implements Cloneable {
    int length;

    Box(int l) {
        length = l;
    }

    protected Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}
        

27. Multithreading with Objects

C++ Multithreading

#include <iostream>
#include <thread>
using namespace std;

class Worker {
public:
    void run() {
        cout << "Worker running" << endl;
    }
};

int main() {
    Worker w;
    thread t(&Worker::run, &w);
    t.join();
}
        

Java Multithreading

class Worker implements Runnable {
    public void run() {
        System.out.println("Worker running");
    }
}

public class Test {
    public static void main(String[] args) {
        Thread t = new Thread(new Worker());
        t.start();
    }
}
        

28. Design Patterns with Classes and Objects

Common OOP Design Patterns

Pattern Purpose Singleton Only one instance Factory Create objects without specifying class Observer Event-driven systems Decorator Add behavior dynamically

🔥 Singleton in C++ Example

class Singleton {
private:
    static Singleton *instance;
    Singleton() {}

public:
    static Singleton* getInstance() {
        if (!instance)
            instance = new Singleton();
        return instance;
    }
};

Singleton* Singleton::instance = nullptr;
        

29. Future of Object-Oriented Programming

Modern Trends:

• C++ evolving toward more functional styles (C++20, C++23).
• Java adopting records, sealed classes, pattern matching.
• Increased distributed object systems (gRPC, REST APIs).
• Emphasis on memory efficiency and parallelism.

30. Final Thoughts: Building from Chip to Cloud

From the tiny transistor flips inside a CPU, ➡ to compiling memory layouts, ➡ to creating complex object-oriented systems, ➡ to network-distributed microservices, ➡ to cloud-native architectures —

👉 Everything starts with understanding how objects really behave!

Mastering OOP, especially Classes and Objects, opens up:

• Writing better software,
• Designing scalable systems,
• Innovating futuristic applications (AI, IoT, Blockchain).

📚 Table of Contents

Part 1: Foundations of Object-Oriented Programming

1. A New Way to Think: Introduction to Object-Oriented Programming (OOP)
2. At the Heart of the Chip: How OOP Principles Emerge in Hardware

Part 2: Building Blocks of the Digital World

1. From Bits to Instructions: Understanding the Foundations of OOP
2. Memory Matters: Object Storage and Management at the Hardware Level

Part 3: Translating Thought into Action

1. From Code to Chip: How Compilers Bring OOP to Life
2. The Blueprint of Software: Fundamentals of Classes and Objects

Part 4: Deep Dive into Language Specifics

1. C++ and Object Modeling: Low-Level to High-Level Perspectives
2. Java and Object Modeling: Architecture, Management, and Execution

Part 5: Practical Applications and Examples

1. Hands-On Coding: Real-World Examples of Classes and Objects
2. Comparing the Giants: Memory Allocation in C++ vs Java

Part 6: Core Concepts Powering Object Behavior

1. The Pillars of OOP: Inheritance, Polymorphism, Encapsulation, and Abstraction
2. When Things Happen: Compile-Time vs Runtime Behavior in OOP

Part 7: Robustness and Communication in Object Systems

1. Safe and Sound: Exception Handling Within Object-Oriented Structures
2. Beyond Local Memory: How Objects Communicate Across Networks

Part 8: Bridging Systems Together

1. Serialization Demystified: Object Transmission in C++ and Java
2. Distributed Object Systems: Connecting the World with OOP

Part 9: OOP in the Age of Connectivity

1. From Classes to Microservices: Building APIs with Object Principles

Part 10: Reflections and Future Vision

1. From Silicon to Cloud: The Epic Journey of Object-Oriented Programming.

The next section will include cache and memory access patterns, followed by OS and network impact, then system-wide design practices.

This Lesson Series are compiled and crafted and teaches by Experienced Software Engineer L.P. Harisha Lakshan Warnakulasuriya.

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