Convert ArrayList to MutableLiveData> in Kotlin

Question

What i am trying to do is to convert the ArrayList<Model> to MutableLiveData<ArrayList<Model>> to be send as a return value. Though i am getting the ArrayList<Model> result correctly,i failed miserably in posting the value to MutableLiveData<ArrayList<Model>>.

This is what i am trying to do...

suspend fun getSeasonBodyWeight(): MutableLiveData<ArrayList<MSBodyWeight>> {
    val x = MutableLiveData<ArrayList<MSBodyWeight>>()
    val y:ArrayList<MSBodyWeight> = getBWeightCoroutine()
    x.postValue(y)
    Log.i(TAG, "Check ${y.size}")
    Log.i(TAG, "Check ${x.value}")
    return x
}

This is what i getting in Logcat

I/FirebaseConnect: Check 2
I/FirebaseConnect: Check null

So what am i doing wrong. Also how to convert ArrayList<Model> to MutableLiveData<ArrayList<Model>>

I am trying to learn Kotlin.. Please bear with me if its a NOOB question.

Thanks

score 2 · Accepted Answer · answered Jun 15 '20 at 11:15

When using postValue and if you check the source code you will find in the method description:

Posts a task to a main thread to set the given value.

Means that the value will not be immediately set, it starts a task to change it. If you mean to change the value immediately you should use:

x.value = y

The difference between the two is that you cannot call setValue from a background thread, that meaning, if you are in a background thread you should call postValue. If you are in the main thread setValue may be used

score 0 · Answer 2 · answered Jun 15 '20 at 11:36

suspend fun getSeasonBodyWeight(): MutableLiveData<ArrayList<MSBodyWeight>> {
    val x = MutableLiveData<ArrayList<MSBodyWeight>>()
    x.value = arrayListOf();
    val y:ArrayList<MSBodyWeight> = getBWeightCoroutine()
    x.postValue(y)
    Log.i(TAG, "Check ${y.size}")
    Log.i(TAG, "Check ${x.value}")
    return x
}

Convert ArrayList to MutableLiveData> in Kotlin

2 Answers2