Why should I double declare a variable in a ViewModel class when using LiveData?-CodePudding

Right now I am following a tutorial where I am developing a simple game app trying to understand and use MVVM app architecture. In my ViewModel class I have a field which contains the score of the player.

The score variable is declared like this:

private val _score = MutableLiveData<Int>()
val score: LiveData<Int>
    get() = _score

Now, in my UI Controller class, I observe the score like this:

viewModel.score.observe(this, Observer { newScore ->
        binding.scoreText.text = newScore.toString()
    })

So, my question is why do I need the second declaration of score? Can't I just have a

val score = MutableLiveData<Int>()

and observe it like above? I tried and it works.

CodePudding user response：

It will work. The point of doing that is to make sure that changes to that variable only occurs from one place, being your ViewModel. It's just a pattern people have followed to make it easier for you to debug and ensure that state of your app/view is correct. One source from Google I found here, although I'm sure there are plenty more