Android RecyclerView使用入门介绍

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:paddingTop="10dp"
    android:paddingBottom="10dp"
    android:paddingRight="20dp"
    android:paddingLeft="20dp">
    <TextView
        android:id="@+id/item_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginEnd="8dp"
        android:padding="15dp"
        android:text="tools"
        android:textColor="#353434"
        android:textSize="20sp"/>
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</LinearLayout>

class RecyclerAdapter(val context: Context) : RecyclerView.Adapter<RecyclerAdapter.MyViewHolder>() {
    inner class MyViewHolder(view: View) : RecyclerView.ViewHolder(view) {
        val textView: TextView = view.findViewById(R.id.item_text)
    }
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
        val itemView = LayoutInflater.from(context).inflate(R.layout.items, parent, false)
        return MyViewHolder(itemView)
    }
    override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
        holder.textView.text = "this is $position"
    }
    override fun getItemCount(): Int {
        return 40
    }
}

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        initRecycler()
    }
    fun initRecycler() {
        val adapter = RecyclerAdapter(this)
        val recyclerView = findViewById<RecyclerView>(R.id.recyclerView)
        recyclerView.adapter = adapter
        val layoutManager = LinearLayoutManager(this)
        layoutManager.orientation = RecyclerView.VERTICAL
        recyclerView.layoutManager = layoutManager
    }
}