Kit

Provide an interface for creating families of related or dependent objects without specifying their concrete classes.

Use the Abstract Factory pattern when

• a system should be independent of how its products are created, composed and represented
• a system should be configured with one of multiple families of products
• a family of related product objects is designed to be used together, and you need to enforce this constraint
• you want to provide a class library of products, and you want to reveal just their interfaces, not their implementations
• the lifetime of the dependency is conceptually shorter than the lifetime of the consumer.
• you need a run-time value to construct a particular dependency
• you want to decide which product to call from a family at runtime.
• you need to supply one or more parameters only known at run-time before you can resolve a dependency.

• Selecting to call the appropriate implementation of FileSystemAcmeService or DatabaseAcmeService or NetworkAcmeService at runtime.
• Unit test case writing becomes much easier

• Dependency injection in java hides the service class dependencies that can lead to runtime errors that would have been caught at compile time.

• javax.xml.parsers.DocumentBuilderFactory
• javax.xml.transform.TransformerFactory
• javax.xml.xpath.XPathFactory

• Design Patterns: Elements of Reusable Object-Oriented Software