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kotlin: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.recyclerview.widget.RecyclerView.setAdapter

byMR

January 3, 2023

I tried to make recyclerview on fragment with data from firestore.

I’ve made viewHolder and Adapter.

And all seems fine but I keep facing below issue:

java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.recyclerview.widget.RecyclerView.setAdapter(androidx.recyclerview.widget.RecyclerView$Adapter)' on a null object reference

I know many questions are already asked but I can’t solve this problem with their solution.

Please help me which part cause problem in my code.

Data Class

data class DiaryCard(var name: String, var stepCount: String, var mood: Long? =2131230873, var diary: String? = "" )

Fragement:

class AllDiaryFragment : Fragment() {
private val db = Firebase.firestore
private val userDB = db.collection("users")
private val diaryDB = db.collection("diary")

private val userId = Firebase.auth.currentUser?.uid

private var _binding: FragmentAllDiaryBinding? = null
private val binding get() = _binding!!

private var username: String = "안녕"
private var userStepCount: String = "342"

private var items: ArrayList<DiaryCard> = ArrayList()


override fun onCreateView(
    inflater: LayoutInflater, container: ViewGroup?,
    savedInstanceState: Bundle?
): View? {
    _binding = FragmentAllDiaryBinding.inflate(inflater, container, false)
    val view = binding.root

    userDB
        .document("$userId")
        .get()
        .addOnSuccessListener { document ->
            username = document.data?.getValue("name").toString()
            userStepCount = document.data?.getValue("todayStepCount").toString()
        }


    diaryDB
        .get()
        .addOnSuccessListener { documents ->
            for (document in documents) {
                items.add(
                    DiaryCard(
                        username,
                        userStepCount,
                        (document.data?.getValue("todayMood") as Map<*,*>)["image"] as Long,
                        document.data?.getValue("todayDiary").toString(),
                    )
                )
            }

        }

    var adapter = DiaryCardAdapter(requireContext(), items)
    recyclerDiary.adapter = adapter
    recyclerDiary.layoutManager = LinearLayoutManager(
        context,
        RecyclerView.VERTICAL,
        false
    )

    return view
 }
}

Adapter

class DiaryCardAdapter(val context: Context, items: ArrayList<DiaryCard>) :
    RecyclerView.Adapter<DiaryCardAdapter.CardViewHolder>() {

    var items = items

    inner class CardViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
        var userNameView: TextView = itemView.findViewById<TextView>(R.id.userName)
        var userStepCountView: TextView = itemView.findViewById<TextView>(R.id.userStepCount)
        var userMoodView: ImageView = itemView.findViewById<ImageView>(R.id.userMood)
        var userDiaryView: TextView = itemView.findViewById<TextView>(R.id.userDiary)

        fun bind(position: Int) {
            userNameView.text = items[position].name
            userStepCountView.text = items[position].stepCount
            userMoodView.setImageResource((items[position].mood ?: 2131230873).toInt())
            userDiaryView.text = items[position].diary

        }
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CardViewHolder {
        val v = LayoutInflater.from(parent.context).inflate(R.layout.diary_card, parent, false)
        return CardViewHolder(v)
    }

    override fun onBindViewHolder(holder: CardViewHolder, position: Int) {
        holder.bind(position)
    }

    override fun getItemCount(): Int = items.size
}