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What is assisted injection?
Assisted injection is a dependency injection (DI) pattern that is used to construct an object where some parameters may be provided by the DI framework and others must be passed in at creation time (a.k.a “assisted”) by the user.
Should factory class be static?
No, factory class by default shouldn’t be static. Actually, static classes are not welcomed in OOP world since they can also convey some state and therefore introduce global application state. If you need only one factory object to be present, you can control it’s creation through singleton pattern.
Are factory classes singletons?
Re: should a factory pattern always be implemented as a singleton? They both are different design patterns. Factory pattern delegates the responsibility of creating the instances (objects) to the factory classes. But, singleton pattern ensures the creation of an object should be done only once per application instance.
When to use dependency injection or static factories?
Generally speaking, I’d only use static factories for things you need ubiquitous access to, and that are guaranteed to be available in all environments we could ever want to run the code (such as Logging). For everything else, I’d use plain old dependency injection.
How to inject value into a static variable?
If you print out the GlobalValue.DATABASE, a null will be displayed. To fix it, create a “none static setter” to assign the injected value for the static variable. For example : Founder of Mkyong.com, love Java and open source stuff. Follow him on Twitter.
How to use dependency injection in object oriented?
In the spirit of creativity and future clarity, one might inject a DI instance into a factory class to resolve any dependencies of the desired, potential product instances. Let your conditional inside the Factory control the logic. Allow the DI instance to handle instance creation and dependency resolution.
Why do we use dependency injection in AspectJ?
This can allow you to intercept (or “advise” to use AspectJ terminology) the constructor of the class and inject the relevant properties, maybe given a special attribute. Factories make testing a pain and don’t allow easy swapping of implementations.