当在 MutableLiveData 变量上调用 postValue 时，公开的 LiveData 调度如何变化？

Question

In ViewModel:

private var _someData : MutableLiveData<Boolean> = MutableLiveData()
var someData: LiveData<Boolean> = _someData

public fun someMethod(){
    _someData.postValue(true)
}

In Fragment:

viewModel.someData.observe(this, Observer {
    //change posted on MutableLiveData but this LiveData received the changes.
})

Since someData and _someData are 2 different variables, how the onChanged() method of someData is invoked even if value is posted on _someData and changes are observed for exposed LiveData ?

Answer 1

Both variables reference the same object. The only difference is that you are exposing a LiveData so clients can't modify its value. As it is just one object, when you update _someData , someData is also updated.