androidkotlinandroid-livedatamutablelivedata

Why does LiveData better than MutableLiveData?

In many samples i see that:

 class DataViewModel{
         val data:LivaData<Int>
             get() = _data 

         private val _data = MutableLiveData<Int>()

    }

But more simply looks like this:

 class DataViewModel{
         val data = MutableLiveData<Int>()

    }

so, why need this more complicated code construction with 2 fields?

Solution

  • It's a practice designed to restrict modification of the value from outside the class.

    LiveData is read-only. MutableLiveData, as the name implies, allows one to change the value it holds.

    If you expose a MutableLiveData directly, like in your second example, any code which can access that data field could also modify the value it holds.

    Exposing the ability to change data's content from outside DataViewModel class could make it harder to debug and reason about where data's content is coming from at any given time.