#21 Class and Object Theory in JAVA | Skyhighes | Lecture 21

Classes and Objects: Foundations of OOP

Object-Oriented Programming (OOP): A programming paradigm that revolves around "objects" as fundamental building blocks. It models real-world entities and their relationships, promoting code reusability, maintainability, and modularity.
Classes: Blueprints or templates that define the characteristics (attributes) and behaviors (methods) of objects. They specify what objects of that class will look like and what they can do.
Objects: Instances of classes. They are concrete entities with specific state (values of their attributes) and the ability to perform actions (methods).
Key Concepts:

Class Declaration:

Use the class keyword followed by the class name.
Enclose attributes (variables) and methods (functions) within curly braces.
Java
public class Dog {
String breed;
int age;

void bark() {
System.out.println("Woof!");
}
}
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Object Creation (Instantiation):

Use the new keyword followed by the class name and a constructor call.
Java
Dog myDog = new Dog();
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Attributes (Member Variables):

Represent the data associated with an object.
Define them within the class using various data types (e.g., int, String, boolean).
Methods (Member Functions):

Define the actions that objects can perform.
Contain code blocks that operate on the object's attributes and other data.
Accessing and Modifying Object State:

Use the dot (.) operator to access attributes and methods of an object.
Java
myDog.breed = "Labrador";
myDog.bark(); // Output: "Woof!"
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Understanding the Relationship:

A class is like a recipe for creating objects.
Each object is a unique instance of the class, with its own set of attribute values.
Objects interact with each other by calling each other's methods.
Benefits of OOP:

Encapsulation: Bundling data and behavior within objects, protecting data integrity.
Inheritance: Creating new classes (subclasses) that inherit properties and behaviors from existing classes (superclasses), promoting code reusability.
Polymorphism: Objects of different classes responding to the same method call in different ways, allowing for flexible and adaptable code.
Remember: Classes and objects are fundamental to OOP and essential for structuring Java programs effectively. Understanding their relationship and properties is crucial for building well-organized and maintainable software.