Lesson: Object-Oriented Programming Concepts
If you’ve never used an object-oriented programming language before, you’ll need to learn a few basic concepts before you can begin writing any code. This lesson will introduce you to objects, classes, inheritance, interfaces, and packages. Each discussion focuses on how these concepts relate to the real world, while simultaneously providing an introduction to the syntax of the Java programming language.
What Is an Object?
An object is a software bundle of related state and behavior. Software objects are often used to model the real-world objects that you find in everyday life. This lesson explains how state and behavior are represented within an object, introduces the concept of data encapsulation, and explains the benefits of designing your software in this manner.
What Is a Class?
A class is a blueprint or prototype from which objects are created. This section defines a class that models the state and behavior of a real-world object. It intentionally focuses on the basics, showing how even a simple class can cleanly model state and behavior.
What Is Inheritance?
Inheritance provides a powerful and natural mechanism for organizing and structuring your software. This section explains how classes inherit state and behavior from their superclasses, and explains how to derive one class from another using the simple syntax provided by the Java programming language.
What Is an Interface?
An interface is a contract between a class and the outside world. When a class implements an interface, it promises to provide the behavior published by that interface. This section defines a simple interface and explains the necessary changes for any class that implements it.
What Is a Package?
A package is a namespace for organizing classes and interfaces in a logical manner. Placing your code into packages makes large software projects easier to manage. This section explains why this is useful, and introduces you to the Application Programming Interface (API) provided by the Java platform.
Questions and Exercises: Object-Oriented Programming Concepts
Use the questions and exercises presented in this section to test your understanding of objects, classes, inheritance, interfaces, and packages.
What are the characteristics of Object Oriented programming language?
Encapsulation – Encapsulation is capturing data and keeping it safely and securely from outside interfaces.
Inheritance– This is the process by which a class can be derived from a base class with all features of base class and some of its own. This increases code reusability.
Polymorphism– This is the ability to exist in various forms. For example an operator can be overloaded so as to add two integer numbers and two floats.
Abstraction– The ability to represent data at a very conceptual level without any details.