What is a Factory Design Pattern?
The Factory Design Pattern is a widely used design pattern in software development that provides an interface for creating objects without specifying the exact class of object that will be created. It is part of the creational design patterns and is often used when the exact type of object that needs to be created is dependent on the context or input provided at runtime. This pattern encapsulates the object creation logic and provides a high level of abstraction, making the code more maintainable and flexible.
In a Factory Design Pattern, a factory class is responsible for creating and returning an instance of a class based on the input provided. This class is often referred to as the “factory” and the class that is created is called the “product.” The factory class contains a method that determines which type of product to create based on the input and then instantiates and returns the appropriate product object.
One of the key advantages of using the Factory Design Pattern is that it decouples the client code from the specific classes that are being created. This means that the client code does not need to know about the specific classes that are being created, making it easier to extend the system in the future. For example, if a new product class needs to be added, the client code does not need to be modified as the factory class will handle the creation of the new product.
The Factory Design Pattern is often used in scenarios where there are multiple classes that share a common interface and the client code needs to choose between these classes based on certain criteria. For instance, a car rental system might have different types of cars, such as sedans, SUVs, and trucks. The client code can use the factory pattern to request a specific type of car based on the customer’s preference, without needing to know the implementation details of each car type.
Here’s a simple example to illustrate the Factory Design Pattern:
“`java
// Product class
class Car {
public void drive() {
System.out.println(“Driving a car…”);
}
}
// Concrete Product class
class Sedan extends Car {
public void drive() {
System.out.println(“Driving a sedan…”);
}
}
class SUV extends Car {
public void drive() {
System.out.println(“Driving an SUV…”);
}
}
// Factory class
class CarFactory {
public Car createCar(String type) {
if (type.equalsIgnoreCase(“sedan”)) {
return new Sedan();
} else if (type.equalsIgnoreCase(“SUV”)) {
return new SUV();
} else {
return null;
}
}
}
// Client code
public class Main {
public static void main(String[] args) {
CarFactory factory = new CarFactory();
Car car = factory.createCar(“sedan”);
car.drive();
}
}
“`
In this example, the `CarFactory` class acts as the factory and determines which type of `Car` to create based on the input string. The client code simply requests a car from the factory and uses it without knowing the specific implementation details.
Overall, the Factory Design Pattern is a powerful tool for creating objects in a flexible and maintainable way, making it an essential pattern for any software developer’s toolkit.
