Object-oriented programming (OOP) is a programming paradigm that organizes data and behavior into reusable units called objects. Objects have attributes (also called fields or properties) that store data, and methods (also called functions or operations) that perform actions on the data. OOP allows programmers to create modular, reusable, and maintainable code.
There are four main concepts of OOP in Java: abstraction, encapsulation, inheritance, and polymorphism. These concepts are also known as the pillars of OOP. Let me explain each of them briefly:
- Abstraction is the process of hiding the implementation details and showing only the essential features of an object. Abstraction helps to reduce complexity and increase efficiency by focusing on what an object can do rather than how it does it. For example, when you use a phone, you don't need to know how it works internally, you only need to know how to make a call, send a message, etc. In Java, abstraction can be achieved by using abstract classes and interfaces.
- Encapsulation is the process of wrapping data and methods into a single unit called a class. Encapsulation helps to protect the data from being accessed or modified by other classes or objects. Encapsulation also provides data hiding, which means that the internal state of an object is not visible to the outside world. Encapsulation also enables information hiding, which means that the details of how a class or an object works are not exposed to the outside world. In Java, encapsulation can be achieved by using access modifiers (such as private, protected, public) and getters and setters.
- Inheritance is the process of acquiring the properties and behaviors of a parent class by a child class. Inheritance helps to reuse existing code and avoid duplication. Inheritance also enables hierarchical classification, which means that objects can be grouped into categories based on their common characteristics. Inheritance also allows for code extensibility, which means that new features can be added to existing classes without modifying them. In Java, inheritance can be achieved by using the extends keyword.
- Polymorphism is the ability of an object to take different forms depending on the context. Polymorphism helps to achieve dynamic binding, which means that the appropriate method or operation is executed at runtime based on the type of the object. Polymorphism also enables code flexibility, which means that different objects can be used interchangeably in different situations. In Java, polymorphism can be achieved by using method overloading and method overriding.
