使用来自 Firebase 的 LivaData 填充 Android Spinner

如何解决使用来自 Firebase 的 LivaData 填充 Android Spinner

如何使用已保存在 Firebase RTDB 中的数据加载微调器？

我在想这样的事情可能会奏效

    viewModel.liveCharacterModel.observe(this,Observer { spinnerData ->
            val spinnerAdapter =  ArrayAdapter(this,android.R.layout.simple_spinner_item,spinnerData)
            select_character.adapter = spinnerAdapter
        })

但我在 ArrayAdapter 上遇到错误 “不能使用提供的参数调用以下任何函数。”

如果相关，这是我的 characterViewModel 代码

class CharacterViewModel : ViewModel() {

    private val dbCharacterModels = FirebaseDatabase.getInstance().getReference(NODE_CHARACTERS)

    //add data from db to this list for use in the
    // characterModelAdapter class for the recycler view
    private val _characters = MutableLiveData<List<CharacterModel>>()
    val characterModel: LiveData<List<CharacterModel>>
        get() = _characters

    //live data for new data added
    private val _liveCharacters = MutableLiveData<CharacterModel>()
    val liveCharacterModel: LiveData<CharacterModel>
        get() = _liveCharacters

    private val _result = MutableLiveData<Exception?>()
    val result: LiveData<Exception?>
        get() = _result

    private val childEventListener = object : ChildEventListener {

        override fun onChildAdded(snapshot: DataSnapshot,previousChildName: String?) {
            val liveCharacterModel = snapshot.getValue(CharacterModel::class.java)
            liveCharacterModel?.id = snapshot.key
            _liveCharacters.value = liveCharacterModel
        }

        override fun onChildChanged(snapshot: DataSnapshot,previousChildName: String?) {
            val liveCharacterModel = snapshot.getValue(CharacterModel::class.java)
            liveCharacterModel?.id = snapshot.key
            _liveCharacters.value = liveCharacterModel
        }

        override fun onChildRemoved(snapshot: DataSnapshot) {
            val liveCharacterModel = snapshot.getValue(CharacterModel::class.java)
            liveCharacterModel?.id = snapshot.key
            liveCharacterModel?.charDeleted = true
            _liveCharacters.value = liveCharacterModel
        }

        override fun onChildMoved(snapshot: DataSnapshot,previousChildName: String?) {
            TODO("Not yet implemented")
        }

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

    }

    /*
        Add character to DB,save a character under the characters node in the DB with a
        unique key id.

     */
    fun addCharacter(character: CharacterModel) {

        character.id = dbCharacterModels.push().key
        character.id?.let {
            dbCharacterModels.child(it).setValue(character).addOnCompleteListener {
                if (it.isSuccessful) {
                    _result.value = null
                } else {
                    _result.value = it.exception
                }
            }
        }

    }

    fun getDBUpdates() {
        dbCharacterModels.addChildEventListener(childEventListener)
    }

    /*
     Fetch data from the db,make sure the data is not null,add it to a list and assign
     it to the mutable list which gets displayed in the fragment
     */
    fun getCharacters() {
        dbCharacterModels.addListenerForSingleValueEvent(object : ValueEventListener {
            override fun onDataChange(snapshot: DataSnapshot) {
                if (snapshot.exists()) {
                    val characters = mutableListOf<CharacterModel>()
                    for (characterSnapshot in snapshot.children) {
                        val character = characterSnapshot.getValue(CharacterModel::class.java)
                        character?.id = characterSnapshot.key
                        character?.let { characters.add(it) }
                    }
                    _characters.value = characters
                }
            }

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

        })
    }

    //overrite existing character with new values
    fun editCharacter(character: CharacterModel) {
        dbCharacterModels.child(character.id!!).setValue(character)
            .addOnCompleteListener {
                if (it.isSuccessful) {
                    _result.value = null
                } else {
                    _result.value = it.exception
                }
            }
    }

    fun deleteCharacter(character: CharacterModel) {
        dbCharacterModels.child(character.id!!).setValue(null)
            .addOnCompleteListener {
                if (it.isSuccessful) {
                    _result.value = null
                } else {
                    _result.value = it.exception
                }
            }
    }

    //remove the event listener when fragment is destroyed
    override fun onCleared() {
        super.onCleared()
        dbCharacterModels.removeEventListener(childEventListener)
    }
}

这是我的 CharacterModelAdapter 代码，我用于在回收站视图中显示数据，以防其相关

class CharacterModelAdapter: RecyclerView.Adapter<CharacterModelAdapter.CharacterViewModel>() {

    private var characters = mutableListOf<CharacterModel>()
     var listener: CharacterRecyclerViewListener? = null

    override fun onCreateViewHolder(parent: ViewGroup,viewType: Int) = CharacterViewModel (
        LayoutInflater.from(parent.context)
            .inflate(R.layout.recycler_view_character,parent,false))


    override fun getItemCount() = characters.size

    override fun onBindViewHolder(holder: CharacterModelAdapter.CharacterViewModel,position: Int) {
        holder.view.text_view_name.text = characters[position].name
        holder.view.text_view_race.text = characters[position].race
        holder.view.text_view_class.text = characters[position].classType

        holder.view.edit_character.setOnClickListener {
            listener?.onRecyclerViewButtonClick(it,characters[position]) 
        }
        holder.view.delete_character.setOnClickListener {
            listener?.onRecyclerViewButtonClick(it,characters[position])
        }
    }

    fun setCharcaters(characters: List<CharacterModel>) {
        this.characters = characters as MutableList<CharacterModel>
        notifyDataSetChanged()
    }

    /*
    function that checks if a character is already in the list before adding
    checks if charDeleted is true or false for deleting and also checks which index the character
    is at for editing. notifyDatasetChaged is then called so the recycler view updates and displays
    the changes

     */
    fun addCharacter(character: CharacterModel) {
        if(!characters.contains(character)) {
            characters.add(character)
            notifyDataSetChanged()
        } else {
            val index = characters.indexOf(character)
            if(character.charDeleted) {
                characters.removeAt(index)
            }else {
                characters[index] = character
            }
        }
        notifyDataSetChanged()
    }

    class CharacterViewModel(val view: View): RecyclerView.ViewHolder(view)
}

这是我想在里面实现微调器的弹出片段

class CreateRaidPopupFragment: DialogFragment(),AnkoLogger {
    private lateinit var viewModel: CharacterViewModel
    private val adapter = CharacterModelAdapter()

    override fun onCreateView(
        inflater: LayoutInflater,container: ViewGroup?,savedInstanceState: Bundle?
    ): View? {
        return inflater.inflate(R.layout.fragment_create_raid_popup,container,false)
    }


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

        viewModel.liveCharacterModel.observe(this,spinnerData)
            select_character.adapter = spinnerAdapter
        })
    }
}

解决方法

修复它，我需要改变我的功能

viewModel.characterModel.observe(this,Observer {
        val spinnerAdapter =
            ArrayAdapter(requireContext(),android.R.layout.simple_spinner_item,it)
        select_character.adapter = spinnerAdapter
    })

而且我还需要在此之前调用 getCharacters 函数