What\'s the Difference Between Factory, Factory Method, and Abstract Factory?

Factory vs Factory Method vs Abstract Factory: A Clear Distinction

Understanding the Confusion

Design patterns like Factory, Factory Method, and Abstract Factory can be confusing due to their similarities. To clarify, all three patterns involve object creation, but they differ in their implementation and use cases.

Factory: A Simplified Creation Process

The Factory pattern conceals the logic for object instantiation from the client. It provides a common interface for creating objects, simplifying the client's code. Typically, the Factory class serves as a central point for object creation, reducing the need for repetitive instantiation code.

Factory Method: Subclass-Driven Creation

The Factory Method pattern defines an interface for object creation but delegates the actual instantiation to subclasses. This allows for more flexibility and customization, as subclasses can override the base factory method to create different types of objects. The base class manages the creation process, while subclasses define the specific objects to create.

Abstract Factory: Family-Oriented Creation

The Abstract Factory pattern provides an interface for creating a family of related objects. It eliminates the need to specify the concrete classes of the objects to be created. Instead, clients request a factory object specific to the family of objects they want to create. This ensures that all objects created within a family have consistent behavior and are compatible with each other.

When to Use Each Pattern

• Factory: Suitable for simplified object creation when the type of object to be created is fixed or can be easily determined.
• Factory Method: Ideal when you need to create different types of objects based on the context or subclass-specific logic.
• Abstract Factory: Useful when you need to create multiple related objects that must adhere to consistent interfaces or have complex interdependencies.

Java Example

Here is a simple Java example demonstrating the use of each pattern:

<code class="java">// Factory
class ShapeFactory {
  Shape getShape(String type) {
    if (type.equals("circle")) return new Circle();
    else if (type.equals("square")) return new Square();
    else return null;
  }
}

// Factory Method
abstract class VehicleFactory {
  abstract Vehicle createVehicle();
}
class CarFactory extends VehicleFactory {
  @Override
  Vehicle createVehicle() {
    return new Car();
  }
}

// Abstract Factory
interface UIWidgetFactory {
  Button createButton();
  Label createLabel();
}
class WindowsUIWidgetFactory implements UIWidgetFactory {
  @Override
  Button createButton() {
    return new WindowsButton();
  }
  @Override
  Label createLabel() {
    return new WindowsLabel();
  }
}</code>

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