RecycleView - 没有附加适配器，在 Fragment 中跳过布局

Question

Sup guys,

I am currently implementing the ListAdapter for my RecycleView. While implementing I followed this tutorial: https://medium.com/simform-engineering/listadapter-a-recyclerview-adapter-extension-5359d13bd879

There is a problem with which I am currently struggeling with: Code:

adapter = UsersAdapter()
rvUsers.adapter = adapter

userListLiveData.observe(this, Observer {list->
    adapter.submitList(list)
})

I dont know if I implemented this correctly, because I get the error that the adapter isnt attached.

Here`s my Code:

      class InvoiceListAdapter : ListAdapter<InvoiceModel, InvoiceViewHolder>(InvoiceListDiffCallback()) {
       override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): InvoiceViewHolder {
           return InvoiceViewHolder(LayoutInflater.from(parent.context).inflate(R.layout.fragment_first, parent, false))
       }
   
       override fun onBindViewHolder(holder: InvoiceViewHolder, position: Int) {
           holder.bindTo(position)
       }
   
       override fun getItemCount(): Int {
           val count = super.getItemCount()
           return when(count) {
               0 -> 1
               else -> count
           }
       }
   
   }

class InvoiceListDiffCallback : DiffUtil.ItemCallback<InvoiceModel>() {
   override fun areItemsTheSame(oldItem: InvoiceModel, newItem: InvoiceModel): Boolean {
       return oldItem == newItem
   }

   override fun areContentsTheSame(oldItem: InvoiceModel, newItem: InvoiceModel): Boolean {
       return oldItem == newItem
   }

}

My Fragment:

    class FirstFragment : Fragment() {
    private lateinit var invoiceAdapter: InvoiceListAdapter

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment

        return inflater.inflate(R.layout.fragment_first, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        val items = mutableListOf<InvoiceModel>()
        val layoutManager = LinearLayoutManager(context)

        invoiceAdapter = InvoiceListAdapter()

        invoiceList.layoutManager = layoutManager
        invoiceList.adapter = invoiceAdapter


        for (i in 0..40) {
            print(i)
        }

        items.add(
            InvoiceModel(
                "Einkauf",
                "Digital",
                "27.05.2020 12:00 Uhr",
                "Wasser  gekauft",
                null,
                "Portmonaiee",
                true
            )
        )
        invoiceAdapter.submitList(items)
    }
}




Has anyone an idea how to fix that the adapter isnt attached?

Answer 1

Well you should notify the adapter about the changes in your list. That way they will be shown on the display. You could try with: invoiceAdapter.notifydatasetChanged()

Or this one: invoiceAdapter.notifyItemInserted(items.size - 1)