Difference between Extend and Implement in Dart
Dart, being a powerful and flexible programming language, offers various ways to build classes and extend their functionalities. Two commonly used methods are `extend` and `implement`. While they both allow for code reuse and inheritance, they serve different purposes and have distinct characteristics. This article aims to shed light on the difference between `extend` and `implement` in Dart.
Extend
The `extend` keyword in Dart is used to inherit properties and methods from a superclass. When a class extends another class, it inherits all the public and protected members of the superclass. This means that the subclass can access and use the inherited methods and properties as if they were its own.
For example, consider a superclass called `Animal` with a method `makeSound()`. If we create a subclass called `Dog` that extends `Animal`, we can inherit the `makeSound()` method and use it in the `Dog` class.
“`dart
class Animal {
void makeSound() {
print(‘Some sound’);
}
}
class Dog extends Animal {
void bark() {
print(‘Woof!’);
}
}
void main() {
Dog myDog = Dog();
myDog.makeSound(); // Output: Some sound
myDog.bark(); // Output: Woof!
}
“`
In this example, the `Dog` class extends the `Animal` class and inherits the `makeSound()` method. We can then call `makeSound()` on an instance of `Dog` without any issues.
Implement
On the other hand, the `implement` keyword in Dart is used to implement an interface. An interface is a contract that defines a set of methods that a class must implement. By implementing an interface, a class promises to provide the necessary methods as specified by the interface.
Interfaces in Dart are similar to those in Java, and they help ensure that classes adhere to a certain structure and behavior. When a class implements an interface, it must provide concrete implementations for all the methods declared in the interface.
For example, let’s say we have an interface called `Walkable` with a method `walk()`. To implement this interface, we can create a class called `Cat` that provides an implementation for the `walk()` method.
“`dart
abstract class Walkable {
void walk();
}
class Cat implements Walkable {
@override
void walk() {
print(‘The cat is walking.’);
}
}
void main() {
Cat myCat = Cat();
myCat.walk(); // Output: The cat is walking.
}
“`
In this example, the `Cat` class implements the `Walkable` interface and provides an implementation for the `walk()` method. By doing so, it fulfills the contract specified by the interface.
Conclusion
In conclusion, the main difference between `extend` and `implement` in Dart lies in their purposes. `Extend` is used to inherit properties and methods from a superclass, while `implement` is used to adhere to an interface and provide concrete implementations for its methods. Understanding the distinction between these two methods is crucial for building well-structured and maintainable Dart applications.
