由于变量值 kotlin，如何更新 recyclerView 列表？

Question

I'm doing questionnaire which is based on RV with its own adapter. My answers I send to server api. I would like to enable answers options in the list when I receive 200 response. So I added observed variable in adapter:

var foo: Boolean by Delegates.observable(false) { property, oldValue, newValue ->
        if (newValue){
            Handler().postDelayed({
                notifyItemChanged(0,9)
            }, 1000)

        }
    }

and change it when I receive 200 from server:

AnswersAdapter().foo = true

then at onBindViewHolder I try to enable items:

override fun onBindViewHolder(holder: AnswerHolder, position: Int, payloads: MutableList<Any>) {
        if (payloads.isNotEmpty()) {
            when (payloads[0]) {
                ...
                9 -> {
                    itemEnabler(Constants.ENABLE_CHECKBOX_ITEM)
                }

            }
        } else {
            super.onBindViewHolder(holder, position, payloads)
        }
    }

and finally function for enabling:

fun itemEnabler(type: Int) {
        when (type) {
            Constants.ENABLE_CHECKBOX_ITEM -> {
                for (i in 0 until itemCount) {
                    if (i != checkedPosition) {
                        Timber.i("=--==-=-=-=-")
                        notifyItemChanged(i, Constants.ENABLE_CHECKBOX_ITEM)
                    }
                }
            }
            ....
        }


    }

where checkedPosition is equal to selected answer. But my items can't be enabled in this way:( As I see my function also isn't called from foo variable. What I did wrong and how to fix it?

UPDATE

itemEnabler function is called but items as a result aren't enabled at all

Answer 1

Looks like you recreate adapter in line AnswersAdapter().foo = true You should use something like this code:

class Fragment {
    private val answersAdapter = AnswersAdapter()

    override fun onCreate(savedInstanceState: Bundle?) {
        recycler.adapter = answersAdapter
    }

    // When server return 200
    fun onSuccess() {
        answersAdapter.foo = true // Reuse already created adapter
    }
}

Alternate solution is use model with enabled field

data class ListData(val isChecked: Boolean)

And after this you can use diff-util ( https://developer.android.com/reference/androidx/recyclerview/widget/DiffUtil ) to update all changed data at screen.

And your onBindViewHolder function will be much more simpler:

override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int){
    holder.itemView.checkbox.isEnabled = data[position].enabled
}

There are also good libraries like Groupie ( https://github.com/lisawray/groupie ) that reduces RecyclerViews adapters boilerplate code and already have DiffUtil support under the hood.