In software engineering, dependency injection is a technique whereby one object (or static method) supplies the dependencies of another object. A dependency is an object that can be used (a service).
In Java, before we can use methods of other classes, we first need to create the object of that class (i.e. class A needs to create an instance of class B).
So, transferring the task of creating the object to someone else and directly using the dependency is called dependency injection.
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