Encapsulation

What is Encapsulation

Encapsulation is a core principle in object-oriented programming (OOP) that involves bundling data (attributes) and the methods (functions) that operate on that data into a single unit, typically a class. The main goal is to restrict direct access to an object’s internal state and control how that data is modified.

How Encapsulation Works

Most OOP languages achieve encapsulation using classes. A class defines private fields (data) and public methods to interact with that data.

Code outside the class can’t directly access the private fields; it must use the class’s public methods, which act as a controlled interface.

For instance, a BankAccount class might keep the balance in a private variable and provide a public deposit() method to change it. This method can include logic to ensure the new value is valid (e.g., preventing negative deposits), protecting the object’s integrity.

Why it’s important

Encapsulation leads to more maintainable, secure, and modular code. By hiding internal implementation details, a class can be changed or refactored without affecting other parts of the program, as long as its public interface remains the same.

This also prevents external code from accidentally or maliciously putting an object into an invalid state. For example, if the balance of a bank account is private, it can only be changed by the deposit() or withdraw() methods, which can enforce specific business rules like preventing overdrafts.

It helps manage complexity by allowing programmers to focus on what an object does, rather than how it’s implemented.

Encapsulation is one of the four foundational concepts of OOP, along with inheritance, polymorphism, and abstraction.