Use injectable Navigator instead of callback of ViewModel

[k-kagurazaka]

Issue

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Overview (Required)

This is for suggestion, please close it if you are not a fun of this idea.

The goal of this PR is that remove all callbacks of ViewModel and uses injectable Navigators instead. Currently I completed following tasks:

• Rename AppUtil to WebNavigator and make it injectable.
• Use WebNavigator instead of callback.

I want to get reviews before working remaining tasks, so please don't merge this PR now.

[konifar]

Thanks! WebNavigator seems good. I have a question! 🙋 Do you have any idea other Navigator class for Activity/Dialog?

[k-kagurazaka]

I have two plans:

1. Separate Navigator for each view, like InformationViewNavigator.

Pros.

• Developers cannot dispatch request that navigate to non-reachable view (e.g. dispatch navigateToSponsorsView on SessionsView).

Cons.

• We should create a lot of file (interfaces and Dagger module).

2. Create ViewNavigator that will be used for all transition.

Pros. and Cons. are reverse of plan 1.

Now I think plan 2 is better, what do you think about?

[konifar]

@k-kagurazaka Thanks! I also think 2 is better since this app doesn't have so many views 😃

[k-kagurazaka]

@konifar Thanks for your quick reply. I will try to implement ViewNavigator.

[k-kagurazaka]

I rewrite activity transition by injectable Navigator. Currently some Callback interfaces exist yet, however we should apply MVVM pattern before removing these callbacks. So I changed the focus of PR as changed title.

Would you like to review?

[k-kagurazaka]

I just extract Navigator from BaseActivity 😄

[konifar]

LGTM! :cool: Thanks for great Refactoring! I learned a lot from this