Java OOP(Object Oriented Programming) Concepts - GeeksforGeeks

Java Object-Oriented Programming (OOP) Concepts

• Core Definition: OOP is a programming paradigm based on objects (data and behavior) that models real-world entities to improve code reusability, maintainability, and scalability.
• Fundamental Building Blocks:
  • Class: A blueprint or prototype defining common properties and methods for objects.
  • Object: An instance of a class consisting of state (attributes), behavior (methods), and identity.
• Four Pillars of OOP:
  • Abstraction: Hiding implementation details and showing only essential features (achieved via abstract classes and interfaces).
  • Encapsulation: Wrapping data and methods into a single unit (class) and restricting direct access using private modifiers and public getters/setters.
  • Inheritance: An "is-a" relationship where a subclass acquires the fields and methods of a superclass using the extends keyword.
  • Polymorphism: The ability of an entity to take "many forms." Achieved via Method Overloading (compile-time) and Method Overriding (runtime).
• Association Relationships:
  • Association: A general relationship between independent objects.
  • Aggregation (Weak): A "has-a" relationship where objects have independent lifecycles (e.g., Company and Employees).
  • Composition (Strong): A relationship where the child object cannot exist without the parent (e.g., House and Rooms).
• Inheritance Types in Java: Single, Multilevel, Hierarchical, Multiple (via interfaces), and Hybrid (via interfaces).
• Advantages: Promotes the DRY (Don't Repeat Yourself) principle, modular structure, easier debugging of large systems, and faster development through reusable components.
• Disadvantages: Steeper learning curve, potential memory overhead due to object creation, and increased complexity for very small or simple programs.