二十二、Kotlin进阶学习：简单学习RecyclerView实现列表展示；

1、首先加入RecyclerView依赖包

implementation 'androidx.recyclerview:recyclerview:1.1.0'

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2、项目列表

 

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3、activity_main文件；

 

<androidx.constraintlayout.widget.ConstraintLayout 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"
    tools:context=".MainActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

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4、添加列表子布局文件 list_view；

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">
    <TextView
        android:id="@+id/tv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="a"
        android:padding="10dp"
        android:textSize="20dp"/>
</LinearLayout>

 

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5、添加适配器类 MyAdaptec.kt；

class MyAdapter(var context: Context,var items:List<String>) : RecyclerView.Adapter<MyAdapter.ViewHolder>() {

    // 在此进行布局id的绑定
    class ViewHolder(view: View): RecyclerView.ViewHolder(view) {
        val tv=view.findViewById<TextView>(R.id.tv)
    }

    // 绑定 子布局
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyAdapter.ViewHolder {
        val inflate = LayoutInflater.from(context).inflate(R.layout.list_view, parent, false)
        return ViewHolder(inflate)
    }

    // 列表展示列数
    override fun getItemCount(): Int =items.size

    // 进行数据赋值
    override fun onBindViewHolder(holder: MyAdapter.ViewHolder, position: Int) {
        holder.tv.text=items.get(position)
    }

}

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6、MainActivity.kt

class MainActivity : AppCompatActivity() {

    lateinit var recyclerView: RecyclerView

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        var items=ArrayList<String>()

        for (item in 1..20){
            items.add("Kotlin学习"+item)
        }

        recyclerView=findViewById(R.id.recyclerView)

        recyclerView.adapter=MyAdapter(this,items)

        recyclerView.layoutManager=LinearLayoutManager(this)
    }

}

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7、运行效果；