Hi Experts, Please help me to understand the Factory pattern and Singleton pattern, when we need to use Factory pattern and when use Singleton pattern.
What is the main advantage/disadvantage one over other?
Any suggestion(explanation) will help me lot. Thanks Vijendra Singh
They're not very similar, and thus they don't have advantages over one another. If you're confused, read up first:
Use the singleton pattern when you wish to only allow one instance of an object class to be instantiated.
Use the factory pattern when you need to abstract out the details of instantiation of your object's class.
They do two very different things.
A Factory exists to create one or more copies of a class. It, or a method it exposes, can be provided to another class that needs the dependency, and the dependent class can call the factory method to get an instance.
A singleton exists to create one and ONLY one copy of a class. A reference to the class is obtained statically, but that reference can then be passed around as an instance, unlike a purely static class.