What is the better way to avoid using global variables in Android?

To my knowledge, to use global variable can make code smell bad because of its tight coupling or the problem of testing.

And in my situation, I want to use some objects with IOC/DI and these objects might be dependent within any of the activities of fragments.
So I make a class named Global and put static variables.

public class Global {

    private static ConvertStrategy convertStrategy;
    private static EntityController entityController;

    public static void init(ConvertStrategy convertStrategy, EntityController entityController){
        Global.convertStrategy = convertStrategy;
        Global.entityController= entityController;
    }

    public ConvertStrategy getConvertStrategy(){
        return convertStrategy;
    }

    public EntityController getEntityController (){
        return entityController;
    }
}

Then I can init it in the MainActivity,

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(...);


    Global.init(new OfflineConvertStrategy() , new OfflineController()); 
    ...
    ...
}

So obviously now I'm using Offline algorithm, then other days I can create other type of strategy or controller for online version without changing codes within any dependency to fragments or activities, this is how IOC/DI benefits me.

Sorry for my bad description, hope this image concretize it:

But when the IOC/DI object amount growth up, I feel it's start hard to maintain.

For example ...

    public class Global {
    public static Resources resources;
    public static DateConvertStrategy dateConvertStrategy;

    private static MemberController memberController;
    private static ProjectSearcher projectSearcher;
    private static OfficeController officeController;
    private static EntityController<Project> projectController;
    private static EntityController<IssueType> issuetypeController;
    private static EntityController<Issue> issueController;
    private static EntityController<IssueComment> issueCommentController;
    private static EntityController<Timeline> timelineController;
    private static EntityController<MemberIdCardModel> memberIdCardController;
    private static EntityController<TodoTask> todotaskController;
    ...
    ...
}

I think somehow I overdosed using IOC/DI and global variables...

Please share your idea.