Creational GOF

The Singleton Design Pattern ensures that a class has only one instance and provides a global point of access to it. To achieve thread safety, reflection safety, and serialization safety, you need to handle specific concerns. Let’s explore how to implement a Singleton pattern that addresses these concerns. Key Concepts: Thread Safety: Ensures that the Singleton instance is created in a thread-safe manner, so multiple threads do not create multiple instances. Reflection Safety: Ensures that the Singleton instance cannot be created using reflection, which can bypass the singleton restriction. Serialization Safety: Ensures that the Singleton instance remains a single instance even after deserialization. Implementation Here’s a Singleton implementation that addresses these concerns: ...

The Prototype Design Pattern is a creational pattern that involves creating new objects by copying an existing object, known as the prototype. This pattern is useful when the cost of creating a new object is more expensive than copying an existing one. It allows you to create objects without specifying their exact class and provides a way to clone objects efficiently. Components of the Prototype Design Pattern: Prototype: An interface or abstract class that declares a clone() method for copying itself. ConcretePrototype: Implements the Prototype interface and provides the implementation for the clone() method. Client: Uses the clone() method to create new instances of objects. Simple Example: Let’s create a simple example where we have a Shape interface with a clone() method. We will implement concrete prototypes like Circle and Rectangle that can be cloned. ...

The Factory Design Pattern is a creational pattern that provides a way to create objects without specifying the exact class of the object that will be created. It defines an interface for creating an object, but allows subclasses to alter the type of objects that will be created. Components of the Factory Design Pattern: Product: The interface or abstract class that defines the type of object to be created. ConcreteProduct: Implements the Product interface and defines the specific object to be created. Creator: The interface or abstract class that declares the factory method for creating Product objects. ConcreteCreator: Implements the Creator interface and overrides the factory method to return an instance of ConcreteProduct. Simple Example: Let’s create a simple example where we have a Vehicle interface, and concrete implementations like Car and Bike. We will use a factory to create instances of these vehicles. ...

The Abstract Factory Design Pattern is a creational pattern that provides an interface for creating families of related or dependent objects without specifying their concrete classes. It involves creating an abstract factory interface that defines methods for creating abstract products, and concrete factories that implement this interface to create specific families of products. Components of the Abstract Factory Design Pattern: AbstractFactory: Declares methods for creating abstract product objects. ConcreteFactory: Implements the AbstractFactory interface to create specific products. AbstractProduct: Declares an interface for a type of product object. ConcreteProduct: Implements the AbstractProduct interface. Client: Uses the AbstractFactory to get instances of AbstractProduct. Simple Example: Let’s create a simple example where we have two types of products: Chair and Sofa. We will have two families of products: Modern and Victorian. The Abstract Factory will create the appropriate family of products. ...