OOPs concepts 💖

Object

⇒ An Object is a fundamental unit of Object-Oriented Programming (OOP) that represents real-world entities. It is created from a class and contains the attributes and behaviors defined by the class. Once an object is created, it can execute the methods and access the properties of its class.

---

Class

⇒ A Class is a blueprint for objects. It represents a collection of objects and defines their properties and behaviors. Classes do not take up memory space until an object is created from them.

• A class can be considered as a logical entity that encapsulates data and methods.
• Class names typically start with a capital letter.

Example: A class defines the common properties and methods shared by all objects of the same type.

---

Access Modifiers

In Java, access modifiers control the scope and visibility of classes, methods, and variables. They provide security and define accessibility.

Types of Access Modifiers:

1. Default:

   • If no access modifier is specified, Java treats the variable, method, or class as having the default modifier.
   • Default modifiers are accessible only within the same package. Example:
   • Two code files in the same package can access default methods or variables simply by creating an object of the file containing the methods.

2. Private:

   • Specified using the private keyword.
   • Accessible only within the class in which they are declared.
   • Private modifiers cannot be used on top-level classes or interfaces because they limit access to within the enclosing class.

Example: Private modifiers are typically used for nested classes or data members within a top-level class. Private members can only be accessed using getter and setter methods.

1. Protected:

   • Declared with the protected keyword.
   • Accessible within the same package or in subclasses in different packages.
   • Not accessible in unrelated classes outside the package.

2. Public:

   • Specified with the public keyword.
   • Accessible from any class, package, or subclass, even outside the package.

---

Keyword this

⇒ The this keyword refers to the current object. It is used to access the object’s variables or reference the object itself within a method or constructor.

---

OOP Principles

Object-Oriented Programming (OOP) revolves around four main concepts:

1. Encapsulation:

   • Encapsulation is the process of wrapping up data and methods in a single unit.
   • It promotes data hiding by restricting access to certain components.
   • Example: A class acts as a capsule that holds data (attributes) and methods (behaviors).

2. Polymorphism: Enables methods or objects to perform different tasks based on their implementation.

3. Abstraction: Focuses on exposing only the essential features of an object while hiding the implementation details.

4. Inheritance: Allows one class to inherit the properties and methods of another class, promoting code reuse.

---

Constructors

A constructor is a special type of method in a class:

• It is invoked automatically when an object is created.
• It is used to initialize the properties of an object.
• Constructors share the same name as the class and do not have a return type.

---

follow me for more 💖