在 recyclerview kotlin 中加载更多内容时如何不重写项目？

Question

Community.

I face a problem that a level of logic finds me locked

When I scroll brings new data, but when you enter the adapter, the items are rewritten instead of joining the ones that are already there.

in my fragment:

    private fun loadMoreProductList(root: View) {
    val viewModel = ViewModelProvider(this).get(HomeViewModel::class.java)
    viewModel.setCurrentPage().observe(
        viewLifecycleOwner,
            {
                if (it != null) {
                    postListAdapter.setListDataMore(it, type_data, this)
                    postListAdapter.notifyDataSetChanged()
                    notLoading = true
                    progressbarHome.visibility = View.GONE
                }
            })
    viewModel.makeApiCallListPost(
        root.context, _page.toString()
    )
}

    override fun getLoadMore() {
    _page = _page + 1
    type_data = 1
    loadMoreProductList(View(context))
}

............ ............ ............

in the viewmodel

    var recyclerListPostList: MutableLiveData<List<PostData>> = MutableLiveData()


fun getRecyclerListPostObserver(): MutableLiveData<List<PostData>> {
    return recyclerListPostList
}

fun setCurrentPage(): MutableLiveData<List<PostData>> {
    recyclerListPostList.postValue(null)
    return recyclerListPostList
}

fun makeApiCallListPost(context: Context, _page: String) {
    val retroInstance = RetroInstance.getRetroInstance(context).create(
        RetroService::class.java
    )
    val call = retroInstance.getPostData(
        _page
    )

    call.enqueue(object : Callback<List<PostData>> {
        override fun onResponse(call: Call<List<PostData>>, response: Response<List<PostData>>) {
            if (response.isSuccessful) {
                val destination = response.body()
                destination?.let {
                    recyclerListPostList.postValue(response.body()!!)
                }
            } else {
                recyclerListPostList.postValue(null)
            }
        }

        override fun onFailure(call: Call<List<PostData>>, t: Throwable) {
            t.printStackTrace()
            recyclerListPostList.postValue(null)
        }
    })
}

in the adaptador

    fun setListData(
    data: List<PostData>,
    type_data: Int,
    fragmentCallback: FragmentCallBack
) {
    this.items0 = data as ArrayList<PostData>
    this.fragmentCallback = fragmentCallback
}

fun setListDataMore(
    data: List<PostData>,
    type_data: Int,
    fragmentCallback: FragmentCallBack
) {
    items0.addAll(data as ArrayList<PostData>)
    this.fragmentCallback = fragmentCallback
}

................ ................ ................ ................

I can provide more code if needed

Thank you.

Answer 1

The rewrite or bind all item is because you call

postListAdapter.notifyDataSetChanged()

notifyDataSetChanged() will refresh all the ViewHolder

The easiest solution is just change

notifyDataSetChanged() to notifyItemRangeChanged(startPosition, lastPosition(usually adapter size))