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

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

Answer 1

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

Answer 2

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