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Programming Languages and Techniques I

7.2 Encapsulation and Data Hiding

2 min readLast Updated on July 25, 2024

Object-oriented programming (OOP) principles form the backbone of modern software design. Encapsulation, a key OOP concept, bundles data and methods into a single unit, enhancing code organization and security. This approach simplifies maintenance and improves flexibility in complex systems.

Data hiding, a crucial aspect of encapsulation, restricts direct access to an object's internal data. By using access modifiers and getter/setter methods, developers can control how data is accessed and modified, protecting integrity and enabling abstraction in large-scale applications.

Object-Oriented Programming Principles

Encapsulation in OOP

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  • Encapsulation bundles data and methods operating on that data within a single unit (class) restricts direct access to object components
  • Promotes modularity and organization of code enhances data security by controlling access simplifies maintenance and updates to the codebase
  • Reduces complexity by hiding implementation details improves code flexibility and reusability (ATM machine, Car engine)

Data hiding importance

  • Data hiding restricts direct access to an object's internal data achieved through access modifiers and getter/setter methods
  • Protects data integrity by preventing unauthorized modifications allows for controlled access to object state
  • Enables abstraction by exposing only necessary information facilitates change management in large-scale applications (Bank account balance, Social security number)

Implementing encapsulated classes

  • Class structure uses private data members to store internal state provides public methods to interact with the object
  • Getter methods provide read access to private data can include additional logic or validation
  • Setter methods control write access to private data enforce data validation and business rules
  • Constructor initializes private data members ensures object is in a valid state upon creation
  • BankAccount class demonstrates encapsulation with private balance and public deposit/withdraw methods

Access modifier types

  • Public access modifier allows unrestricted access from any part of the program used for methods and properties that form the class interface
  • Private access modifier restricts access to within the class itself used for internal implementation details and data
  • Protected access modifier allows access within the class and its subclasses used when inheritance is involved to share functionality
  • Comparison:
    1. Public: least restrictive, accessible everywhere
    2. Protected: moderately restrictive, accessible in class hierarchy
    3. Private: most restrictive, accessible only within the class
  • Use private by default to maximize encapsulation use public for methods that need to be called from outside the class use protected sparingly, only when subclass access is necessary
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© 2025 Fiveable Inc. All rights reserved.
AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.

© 2025 Fiveable Inc. All rights reserved.
AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.