Dart Classes

OOP in Dart lets you create objects that have data and functions. You make a blueprint called a class, then create instances of that class with their own data and functions. This makes your code more organized and reusable.

Project - Article Data Source

• Create an abstract class called ArticleDataSource with method getArticle(String id), and deleteArticle(String id).
• Create a class called ArticleLocalDataSource that implements the ArticleDataSource
• Implement each method and print operation, source, and the provided id. For example, calling getArticle('dart-today-and-tomorrow') should print Get Local dart-today-and-tomorrow
• Add a factory constructor to ArticleLocalDataSource and return the object of ArticleLocalDataSource.
• Instantiate ArticleLocalDataSource using the factory constructor and call each methods on the object.
• Create and implement ArticleAPIDataSource exactly like ArticleLocalDataSource but print Get API dart-today-and-tomorrow instead of Get Local dart-today-and-tomorrow.

By the end of this day, you should have a good understanding of how to create classes and objects in Dart, and how to call their methods.

Tips

• Review the basics of classes and objects in Dart. You can use the Dart documentation to learn more about these concepts (https://dart.dev/guides/language/language-tour#classes).
• Create a class with properties and methods. For example:

class Person {
  String name;
  int age;
  
  Person(this.name, this.age);
  
  void sayHello() {
    print('Hello, my name is $name and I am $age years old.');
  }
}

This creates a Person class with two properties (name and age), a constructor that initializes these properties, and a sayHello method that prints a message to the console.

• Instantiate the class and call its methods. For example:

void main() {
  Person person = Person('Alice', 25);
  person.sayHello(); // prints "Hello, my name is Alice and I am 25 years old." to the console
}

This creates a new Person object with the name “Alice” and age 25, and calls its sayHello method.

• Experiment with different types of classes, such as classes with private properties and methods, or classes that inherit from other classes.

class Animal {
  String _name;
  
  Animal(this._name);
  
  void speak() {
    print('My name is $_name.');
  }
}

class Cat extends Animal {
  Cat(String name) : super(name);
  
  void meow() {
    print('Meow!');
  }
}

void main() {
  Cat cat = Cat('Whiskers');
  cat.speak(); // prints "My name is Whiskers." to the console
  cat.meow(); // prints "Meow!" to the console
}

This creates an Animal class with a private _name property and a speak method, and a Cat class that extends Animal and adds a meow method.

Resources

• The official Dart documentation on classes
• Dart Tutorial: OOP in Dart

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