Recyclerview notifyDataSetChanged is not working?-CodePudding

I have a checkbox and a recyclerview in a layout. In the adapter I created functions: selectAll & unSelectAll. I expect all items to be checked/unchecked whenever checkbox(in fragment layout) is checked/unchecked respectively. However nothing seems to happen? I am not sure if it's the notifyDataSetChanged() that is not working or if am using it wrongly. I have checked every possible solution here but i unable not to find one. Any help is appreciated.

In adapter:

class DetailRecyclerAdapter :
  RecyclerView.Adapter<DetailRecyclerAdapter.BindingHolder>() {

  var details: List<ApiDetail>? = null
  var isSelectedAll: Boolean = true

  override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): BindingHolder {
    val layoutInflater = LayoutInflater.from(parent.context)
    val binding = ItemDetailBinding.inflate(layoutInflater, parent, false)
    return BindingHolder(binding)
  }

  override fun onBindViewHolder(holder: BindingHolder, position: Int) {
    val detail = details?.get(position)
    holder.binding.detail = detail

    if (isSelectedAll) {
      holder.binding.checkBox.isChecked = true
    } else if(!isSelectedAll) {
      holder.binding.checkBox.isChecked = false
    }
    
  }

  override fun getItemCount(): Int {
    return details?.size ?: 0
  }

  fun selectAll() {
    isSelectedAll = true
    notifyDataSetChanged()
  }

  fun unSelectAll() {
    isSelectedAll = false
    notifyDataSetChanged()
  }

  class BindingHolder(var binding: ItemDetailBinding) : RecyclerView.ViewHolder(binding.root)
}

In fragment:

    val adapter = DetailRecyclerAdapter()
    
    binding?.checkBox?.setOnCheckedChangeListener { _, isChecked ->
      if (isChecked) {
        adapter.selectAll()
      } else {
        adapter.unSelectAll()
      }
    }


binding?.detailsRecyclerview?.apply {
  layoutManager = LinearLayoutManager(context)
  adapter = DetailRecyclerAdapter()
}

In Layout:

<androidx.recyclerview.widget.RecyclerView
          android:id="@ id/details_recyclerview"
          android:layout_width="match_parent"
          android:layout_height="match_parent"
          android:overScrollMode="never"
          app:search_details="@{viewModel.details}"/>

BindingAdapter

  @BindingAdapter(value = ["search_details"])
  @JvmStatic
  fun RecyclerView.setSearchConditionDetails(apiDetails: ObservableField<List<ApiDetail>>) {

    adapter?.apply {
      this as DetailRecyclerAdapter
      this.details = apiDetails.get()
      notifyDataSetChanged()
    }

  }

CodePudding user response：

This is the problematic code:

binding?.detailsRecyclerview?.apply {
  layoutManager = LinearLayoutManager(context)
  adapter = DetailRecyclerAdapter()
}

You are effectively creating a 2nd instance of the DetailRecyclerAdapter, i.e. DetailRecyclerAdapter() instantiated twice.

The code should read:

val detailRecyclerAdapter = DetailRecyclerAdapter()
    
    binding?.checkBox?.setOnCheckedChangeListener { _, isChecked ->
      if (isChecked) {
        detailRecyclerAdapter.selectAll()
      } else {
        detailRecyclerAdapter.unSelectAll()
      }
    }


binding?.detailsRecyclerview?.apply {
  layoutManager = LinearLayoutManager(context)
  adapter = detailRecyclerAdapter
}

You want to set your detailsRecyclerView.adapter to the instance you created earlier, not a new instance. I renamed the var from adapter to detailRecyclerAdapter to make this clearer.

CodePudding user response：

is there is any data in details list? as detail list seems to be null in adapter.

var details: List<ApiDetail>? = null

but in that case list should not be displayed at all. You can check and debug this if onBindViewHolder() method is being called or not.