Do I need a framework in order to use Dependency Injection?

Question

I have been reading for and practicing dependency injection for the past two days but nothing is working out, and suddenly I found out that there were some frameworks required in order for dependency injection to work. Is that true? Isnt it a bad practice to make my project depend on some framework? Could it be done without the use of a framework?

EDIT: Im new to programming so I dont understand what is the difference between instatiating a class and using its methods (i dont need a framework for that) and using dependency injection and what is better about it

EDIT: Here is an example of me not using a framework and things not working TestNG @Factory annotation + not enough knowledge on Dependency Injection

Guice is not exactly a framework ... but it is way better than what Spring dependency injection can do. — le-doude, Aug 12 '13 at 11:21
Frameworks does not mean "depending on".By using a framework your project does not depend on anything. Frameworks are examples of reusability.And AFAIK you must use framework for DI. — ihsan kocak, Aug 12 '13 at 11:23
If you don't use a framework/library, you must implements your own dependecy injection system, which may be boring... I advice you to use Guice too, here is the [getting started](https://code.google.com/p/google-guice/wiki/GettingStarted) — NiziL, Aug 12 '13 at 11:24
Using Guice makes sense for me because you can avoid lots of conditional logic when you select what type of implementation to be used in a particular situation — Sebin Eapen George, Aug 13 '13 at 11:27

score 8 · Accepted Answer · answered Aug 12 '13 at 11:24

8

No, you don't have to use a framework:

Dependency Injection

Of course you can use a framework too, As someone said you can use Spring Framework and use their annotations. Here you have a tutorial:

Dependency Injection with the Spring Framework

answered Aug 12 '13 at 11:24

John

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2-3 guys above said that I must use a framework. Im confused. – Kaloyan Roussev Aug 12 '13 at 11:26
@J.Kowalski a framework is code that somebody wrote. You can write that code on your own if you think that those libraries that exist are not good for you. – zapl Aug 12 '13 at 11:27
I dont understand what is the difference between instatiating a class and using its methods (i dont need a framework for that) and using dependency injection and what is better about it. – Kaloyan Roussev Aug 12 '13 at 11:29
Yes, you can use a framework but you don't have to. It simplifies a bit the things. You can read the first article, it is explaining very well what dependency injection means. – John Aug 12 '13 at 11:32
can someone help me out here - http://stackoverflow.com/questions/18183894/testng-factory-annotation-not-enough-knowledge-on-dependency-injection – Kaloyan Roussev Aug 12 '13 at 11:41

score 3 · Answer 2 · edited May 18 '16 at 17:11

You don't have to use a framework but it will help you write cleaner code. For instance, if you want to inject a mock into a class without using a framework, you need some way to to that either by adding getters/setters, pass it to the constructor or use public variables.

public class AClassToTest{
   private A aDependentClass; 

   public void aMethodToTest(){
      int i = aDependentClass.someDependentMethod();
      ..
      ..
   }
}

In the above code, aMethodToTest() is dependent of what aDependentClass.someDependentMethod() returns. This means that you should create a mock of class A and mock what someDependentMethod returns. This is still possible without using a framework, for example by adding a getter and setter so that you can set the object A in your testclass:

@Test
public void testAMethodToTest(){
   //here you must set the object A in your AClassToTest object
   //Create a mock of A with desired values
   //and set it using a setter
}

If you for example use spring for dependency injection, it will allow you to set the mock objects in it's IOC container by using it's @Autowire notation. Then you do not need to have setters/getters for your mocked objects which will give you cleaner code

score 0 · Answer 3 · answered Aug 12 '13 at 11:23

0

For dependency injection Guice is great (personal opinion). At least I find it way better than what Spring provides. It is very lightweight too.

https://code.google.com/p/google-guice/

answered Aug 12 '13 at 11:23

le-doude

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Do I need a framework in order to use Dependency Injection?

3 Answers3