**Course Title:** Mastering Dart: From Fundamentals to Flutter Development **Section Title:** Object-Oriented Programming in Dart **Topic:** Introduction to classes and objects in Dart. **Introduction:** In this topic, we'll delve into the world of object-oriented programming (OOP) in Dart. OOP is a fundamental concept in programming that helps organize and structure code, making it more maintainable, scalable, and efficient. We'll explore the basics of classes, objects, and their relationships, laying the groundwork for more advanced topics in OOP. **What are Classes and Objects?** In OOP, a **class** is a blueprint or a template that defines the properties and behavior of an object. A **class** is essentially a design pattern or a template that defines the characteristics of an object. An **object** is an instance of a class, which has its own set of attributes (data) and methods (functions). Think of a class as a cookie cutter and an object as the actual cookie. **Defining a Class in Dart:** In Dart, you can define a class using the `class` keyword followed by the name of the class. Here's an example of a simple `Car` class: ```dart class Car { String color; int speed; void startEngine() { print('Vroom!'); } } ``` In this example, the `Car` class has two properties: `color` and `speed`, and one method: `startEngine()`. **Creating an Object:** To create an object from a class, you need to instantiate it. In Dart, you can do this using the `new` keyword or the regular function call syntax. Here's how you can create an object from the `Car` class: ```dart void main() { Car myCar = new Car(); // or Car myCar = Car(); myCar.color = 'Red'; myCar.speed = 200; myCar.startEngine(); } ``` **Key Concepts:** * **Inheritance**: A class can inherit properties and methods from another class using the `extends` keyword. * **Polymorphism**: A class can have multiple forms, such as different classes that can be treated as a single class. * **Encapsulation**: A class can hide its internal implementation details and only expose the necessary information through public methods. **Practical Takeaways:** * Use meaningful names for your classes and objects. * Keep your classes and objects organized and structured. * Use inheritance and polymorphism to create complex hierarchies of classes and objects. **Best Practices:** * Use the `final` keyword to declare immutable variables and fields. * Use the `const` keyword to declare compile-time constants. * Use the `widget` keyword to define UI widgets in Flutter. **External Resources:** * [Dart documentation: Classes and objects](https://dart.dev/guides/language/language-tour#classes) * [Dart documentation: OOP](https://dart.dev/guides/language/language-tour#oop) **Leave a Comment or Ask for Help:** If you have any questions or need further clarification on any of the concepts covered in this topic, please leave a comment below.

class Car {
  String color;
  int speed;

  void startEngine() {
    print('Vroom!');
  }
}

void main() {
  Car myCar = new Car(); // or Car myCar = Car();
  myCar.color = 'Red';
  myCar.speed = 200;
  myCar.startEngine();
}