从firebase获取数据，但我有错误查看

Question

有人可以帮助我吗？ 我想从firebase获取数据，所有代码已经绿色，但是当我尝试转到我的物联网片段时，它被迫关闭和错误： java.lang.nullpointerexception：itemView.findViewById（r.id.tv_percent）不得null

这是我的IoT fragment

class IOTFragment : Fragment() {

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

    private lateinit var sensorRecyclerView: RecyclerView
    private lateinit var sensorList: ArrayList<Sensor>
    private lateinit var dbRef: DatabaseReference

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View {
        _binding = FragmentIotBinding.inflate(inflater, container, false)
        return binding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        sensorRecyclerView = binding.sensorView
        sensorRecyclerView.layoutManager = LinearLayoutManager(requireActivity())
        sensorRecyclerView.setHasFixedSize(true)

        sensorList = arrayListOf()

        getSensorData()
    }

    private fun getSensorData(){
//        sensorRecyclerView.visibility = View.GONE

        dbRef = FirebaseDatabase.getInstance().getReference("Sensor")

        dbRef.addValueEventListener(object :ValueEventListener{
            override fun onDataChange(snapshot: DataSnapshot) {
                sensorList.clear()
                if (snapshot.exists()){
                    for (sensorSnap in snapshot.children){
                        val sensorData = sensorSnap.getValue(Sensor::class.java)
                        sensorList.add(sensorData!!)
                    }
                    val mAdapter = SensorAdapter(sensorList)
                    sensorRecyclerView.adapter = mAdapter
//
//                    sensorRecyclerView.visibility = View.VISIBLE
                }
            }

            override fun onCancelled(error: DatabaseError) {
                TODO("Not yet implemented")
            }
        })
    }

    override fun onDestroyView() {
        super.onDestroyView()
        _binding = null
    }
}

我的传感器适配器

class SensorAdapter(private val sensorList: ArrayList<Sensor>) :
    RecyclerView.Adapter<SensorAdapter.ViewHolder>() {

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

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        val currentSensor = sensorList[position]
        holder.tvValueSensor.text = currentSensor.data
        holder.tvNameSensor.text = currentSensor.name
    }

    override fun getItemCount(): Int {
        return sensorList.size
    }

    class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
        val tvValueSensor : TextView = itemView.findViewById(R.id.tv_percent)
        val tvNameSensor : TextView = itemView.findViewById(R.id.tittle_parameter)
    }
}

我的数据类传感器

@Parcelize
data class Sensor(
    var data:String? = "",
    var name:String? = ""
):Parcelable

最后我的firebase 在此处输入映像

这就是我的代码

Answer 1

从错误中，我认为您的布局fragment_iot不包含具有ID tv_percent的视图。如果是这样，您也应该添加布局代码。