One of the most frequently posed Spring core interview questions, be ready for it.   Constructor Injection is better than other patterns from all other patterns. It is advisable to utilize constructor injection for every mandatory collaborator and setter injection for every single other property.  Once more, constructor injection guarantees every required property has been fulfilled, and it is essentially impractical to instantiate an object in an invalid state (not having passed its collaborators). When utilizing constructor injection, you don't need to utilize a dedicated mechanism to guarantee required properties are set (other than typical Java mechanism). In case we are using field injection, which is non-final, they are prone to circular dependencies. However, it exposes coupling if there are more than 3 objects as part of the constructor injection. It is also easy to test if we use constructor injection.