Question

我正在尝试将 RecyclerView 放在 Fragment 中。该回收器视图从 Firebase 获取所有数据并将数据放置在适当的位置。我已经尝试过使用不同的方法，但它们都没有奏效，我不知道该尝试什么…… 我使用了一些代码，但它一直说我的 RecyclerView 不能为空。这是我现在使用的代码。我在 youtube 上看到过，但它使用了一个根本不存在的功能。

class InboxFragment : Fragment() {
    lateinit var mRecyclerView: RecyclerView
    lateinit var mDatabase: DatabaseReference

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)


    }

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val view =  inflater.inflate(R.layout.fragment_inbox, container, false)

        mRecyclerView = view.findViewById(R.id.rcView)
        mRecyclerView.setHasFixedSize(true)
        mRecyclerView.layoutManager = LinearLayoutManager(context)
        mDatabase = FirebaseDatabase.getInstance().getReference("notifications")

        logRecyclerView()

        return view
    }

    private fun logRecyclerView(){
        var FirebaseRecyclerAdapter = object : FirebaseRecyclerAdapter<Notifications, viewHolder>(
            Notifications::class.java,
            R.layout.inforow,
            viewHolder::class.java,
            mDatabase
        ){
            fun populateViewHolder(viewHolder: viewHolder, model: Notifications, position: Int){
                viewHolder.itemView.txtTitle.text = model.titulo
                viewHolder.itemView.txtDescription.text = model.descricao
                Picasso.get().load(model.img).into(viewHolder.itemView.imageItem)
            }
        }

        mRecyclerView.adapter = FirebaseRecyclerAdapter
    }


    class viewHolder(itemView: View) : RecyclerView.ViewHolder(itemView){

    }
}

这是我的inforow：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    android:orientation="vertical"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/imageItem"
        android:layout_width="96dp"
        android:layout_height="96dp"
        tools:layout_editor_absoluteX="16dp"
        tools:layout_editor_absoluteY="16dp"
        tools:srcCompat="@tools:sample/avatars"
        android:layout_marginTop="15dp"
        android:layout_marginStart="15dp"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"/>

    <TextView
        android:id="@+id/txtTitle"
        android:layout_width="286dp"
        android:layout_height="39dp"
        android:text="Title"
        android:textColor="#000000"
        android:textSize="24sp"
        android:textStyle="bold"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintLeft_toRightOf="@id/imageItem"
        app:layout_constraintRight_toRightOf="parent"
        android:layout_marginEnd="5dp"
        android:layout_marginTop="15dp"
        android:layout_marginStart="8dp"/>

    <TextView
        android:id="@+id/txtDescription"
        android:layout_width="286dp"
        android:layout_height="53dp"
        android:layout_marginTop="3dp"
        android:layout_marginStart="2.6dp"
        android:text="Description"
        app:layout_constraintLeft_toRightOf="@id/imageItem"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@id/txtTitle" />
</androidx.constraintlayout.widget.ConstraintLayout>

类Notification

class Notifications {
     //Nome do evento
     var titulo: String? = null

     //Sítio onde se realiza
     var localizacao: String? = null

     //URL que redireciona para a página específica
     var urlPag: String? = null

     //Descição do evento
     var descricao: String? = null

     //Imagem
     var img: String? = null

     constructor(){

     }

     constructor(titulo: String?, localizacao: String?, urlPag: String?, descricao: String?, img: String?) {
          this.titulo = titulo
          this.localizacao = localizacao
          this.urlPag = urlPag
          this.descricao = descricao
          this.img = img
     }
}

Answer 1

您的代码中的问题在于，您在数据库中的属性名称与 Notifications 类中的名称不同。基本上，这些是数据库中属性的葡萄牙语版本，这是不正确的。名称必须匹配。要解决此问题，您应该为每个属性使用注释，如以下代码行所示：

@get:PropertyName("title")
@set:PropertyName("title")
@PropertyName("title")
var titulo: String? = null,

RecyclerView 不适用于 Fragment |科特林 |火力基地

1 个答案: