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What is constructor injection and setter injection?
When constructor injection is used to inject the dependency, it is done by using constructor on any Spring-managed bean, whereas the Setter injection uses setter methods like set dependency() for the purpose of injecting dependency on any of the bean-managed by the Spring’s IOC container.
When should we go for Setter injection and constructor injection?
Use Setter injection when a number of dependencies are more or you need readability. Use Constructor Injection when Object must be created with all of its dependency.
Why is Autowired null?
The field annotated @Autowired is null because Spring doesn’t know about the copy of MileageFeeCalculator that you created with new and didn’t know to autowire it.
What will happen if setter based and constructor based injection is applied on same class?
Overriding: Setter injection overrides the constructor injection. If we use both constructor and setter injection, IOC container will use the setter injection. Changes: We can easily change the value by setter injection. It doesn’t create a new bean instance always like constructor.
How to inject CAR1 and CAR2 in factory constructor?
First approach that comes to my mind is to inject Car1 and Car2 in factory constructor but it is against factory approach because factory will return always the same object. The second approach is to inject servicelocator but it’s antipattern everywhere.
When to use constructor based injection in spring?
Dependency Injection is a practice to pass dependent object to other objects. Spring has two types of Dependency Injection : Constructor based Injection -When container call the constructor of the class. It should be used for mandatory dependencies.
What is the difference between IOC and dependency injection in spring?
Dependency Injection in Spring 1 6.1. Setter Injection. Setter-based DI is realized by calling setter methods on your beans after invoking a no-argument constructor or no-argument static factory method to instantiate your bean. 2 6.2. Constructor Injection. 3 6.3. Interface Injection.
What’s the difference between constructor injection and setter injection?
Both types of injection has their own pros and cons. Below is a list of some differences − Constructor-based DI fixes the order in which the dependencies need to be injected. Setter-based DI helps us to inject the dependency only when it is required, as opposed to requiring it at construction time.