What is the difference between the factory pattern and the singleton pattern?

What is the difference between the factory pattern and the singleton pattern?

The factory pattern is used to create objects without specifying the exact class of object that will be created, while the singleton pattern ensures that a class has only one instance and provides a global point of access to it.

Can you give me an example of the factory pattern?

Sure! In a car manufacturing system, a CarFactory class can create different types of cars (like Sedan, SUV) based on input parameters, without the client needing to know the specific classes.

And how does the singleton pattern work?

The singleton pattern restricts a class to a single instance. For example, a ConfigurationManager class can be designed as a singleton to ensure that all parts of an application use the same configuration settings.

When should I use one pattern over the other?

Use the factory pattern when you need to create multiple instances of different classes, and use the singleton pattern when you need to control access to a single instance of a class.