Difference between Setter Injection and Constructor Injection.When should we go for Setter Injection and Constructor Injection.

Difference Between setter injection and Constructor injection

Setter Injection	Constructor Injection
Setter injection performs injection after creating bean class object so it is bit delayed injection.	Constructor injection perform injection while creating bean class object so no delay in injection.
Supports cyclic dependency.	Doesn’t Supports cyclic dependency.
tag is required.	tag is required.
To perform setter injection on “n-properties” in all angles “n-setter” method are required.	Ton perform constructor injection on n properties in all angle n! Constructor is required.
If all properties are configured for setter injection then container crates bean class object using 0-param constructor.	If any property is configured for constructor injection container class object using parameterized constructor.
Partial dependency can be injected using setter injection.	Partial dependency is Not possible by constructor injection.
Setter injection overrides the constructor injection. If we use both constructor and setter injection, IOC container will use the setter injection.	Vice-versa not possible.
We can easily change the value by setter injection because It doesn't create a new bean instance. So setter injection is flexible.	In case of constructor injection it is not easy because it creates new instance for each. So Constructor injection is not flexible.
Setter injection makes bean class object as mutable [We can change].	Constructor injection makes bean class object as immutable [We cannot change].
In case of setter injection we cannot assigned the value to final field variable.	But in case of Constructor injection we can   assigned the value to final field variable.
One of the drawback of setter injection is that it does not ensures dependency Injection which means you may have an object with incomplete dependency.	On other hand constructor Injection does not allow you to construct object, until your dependencies are ready.

Now when should we go for Setter Injection and Constructor Injection?

1. If bean class contains only one property or if all the properties of bean class should participate in dependency injection then go for constructor injection, because constructor injection is very faster than setter injection.
2. If bean class contains more than one property and there is no need of making all properties participating in dependency injection, then we need to go for setter injection.