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Which is better setter injection and constructor injection?
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. Spring code generation library doesn’t support constructor injection so it will not be able to create proxy.
What is the difference between constructor and setter?
The big difference is the constructor is called once and only once right at the start of the object’s life. Setters may be called many times during the life of the object. The job of a constructor is to put a newly created object into a valid initial state before that object is used.
Why constructor based dependency injection is better?
So to keep your code independent of Spring, use constructor arguments for injection. This applies to tests; you’ll have an easier time instantiating and testing the class in a normal unit test, without needing to configure an application context or the complexity that comes along with setting up an integration test.
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.
When to use constructor based Dependency injection in Java?
When constructor is used, setup of this class for testing is much easier, there is no need to analyze how class under test is implemented. To make it simple, let us say that we can use constructor based dependency injection for mandatory dependencies and setter based injection for optional dependencies.
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.
Can a required dependency be instantiated in a constructor?
A class that takes a required dependency as a constructor argument can only be instantiated if that argument is provided (you should have a guard clause to make sure the argument is not null) (or use a non-nullable type in Kotlin).