Hey guys, for the sake of studying, I am digging inside the code of the abstract class

LiveData

. I wonder, why can’t I call

postValue

or

setValue

If I subclass a LiveData?

private val someInstanceOfLiveData = object : LiveData<String>(){}

fun test(){
    someInstanceOfLiveData.setValue() // Cannot access 'setValue': it is protected/*protected and package*/ in '<no name provided>'
    someInstanceOfLiveData.postValue() // Cannot access 'postValue': it is protected/*protected and package*/ in '<no name provided>'
}

from my understanding,

object : LiveData<String>(){}

is a subclass of the abstract

LiveData

class. If it is a subclass, why can’t I call

postValue()/setValue()

, which are declared as

protected

inside the

LiveData

?

LiveData is immutable, use

MutableLiveData

@Samme Kleijn This does not answer my question. I know

MutableLiveData

is a subclass of

LiveData

. But why I can’t subclass LiveData and call postValue/setValue on it?

Only the subclass itself can call protected methods. You're trying to call the mutator methods from outside.

Sorry, made a mistake, indeed I meant read-only.

Hey @Adam Powell “Only the subclass itself can call protected methods” Isn’t my anonymous object a subclass of the LiveData too? So do you mean that only the fact that I call it outside of the androidx.lifecycle package is what blocking me?

No, what's blocking you is that you're trying to call it from outside of your subclass declaration - you can only call them inside the

{}

that comes after your

object : LiveData<String>()

. You're trying to call them from outside, which would break encapsulation of

protected

.

Ohhhhh now I get it! so what

MutableLiveData

does is just taking the postValue() and setValue(), and overriding it simply for the sake of making the methods public. I did something similar now:

private val someInstanceOfLiveData = object : LiveData<String>(){

    public override fun setValue(value: String?) {
        super.setValue(value)
    }

    public override fun postValue(value: String?) {
        super.postValue(value)
    }

}

fun test(){
    someInstanceOfLiveData.setValue("")
    someInstanceOfLiveData.postValue("")
}

Thank you my friend 🙂 🍕🍻 @Adam Powell