RecyclerView高级控件

RecyclerView是Android 及其重要的一个高级UI控件，使用频率及其的高，APP的90%以上的页面都会使用的到。由于其出色的性能和插拔式的架构设计，被全世界广大开发者一致称赞。

LinerLayoutManager列表布局

纵向列表

recyclerView.layoutManager =LinearLayoutManager(context, VERTICAL, false)
recyclerView.adapter = MyAdapter()

横向列表

recyclerView.layoutManager =LinearLayoutManager(context, HORIZONTAL, false)
recyclerView.adapter = MyAdapter()

数据源适配器

inner class MyAdapter : RecyclerView.Adapter<ViewHolder>() {
        // 【必须复写】创建ItemView的ViewHolder，用于后续的数据绑定
        override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
          val view =LayoutInflater.from(context).inflate(R.layout.item_view_staggered, parent, false)  
          return ViewHolder(view)
        }

        // 【必须复写】告诉RecyclerView列表上item的条数
        override fun getItemCount(): Int {
            return 20
        }

        // 【必须复写】item的数据绑定
        override fun onBindViewHolder(holder: ViewHolder, position: Int) {
            holder.itemView.item_head.setImageResource(R.drawable.icon_jetpack)
            holder.itemView.item_name.text = "【${position}】移动端架构师体系课"
            holder.itemView.item_message.text =
                "移动开发“两极分化”，没有差不多的“中间层,唯有尽早成长为架构师，你的职业道路才能走的更远更稳"
        }
    }

    // 创建一个ViewHolder 必须继承自 RecyclerView.ViewHolder。用于后续的数据绑定
    inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {

    }

案例

代码结构：

MainActivity.kt

package com.example.listexample

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
val list=listOf<String>("first","second","thrid","etc...")
        var recyclerView=findViewById<RecyclerView>(R.id.recyclerView)
        recyclerView.layoutManager=LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false)
        recyclerView.adapter=ItemAdapter(list)
    }
}

ItemAdapter.kt

package com.example.listexample

import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import androidx.appcompat.view.menu.ActionMenuItemView
import androidx.recyclerview.widget.RecyclerView

class ItemAdapter(val items:List<String>) : RecyclerView.Adapter<ItemAdapter.ViewHolder>(){



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

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.bindView(items[position])
    }

    override fun getItemCount()=items.size
    inner  class  ViewHolder(itemView: View): RecyclerView.ViewHolder(itemView  ){

fun bindView(item: String){


     val textView= itemView.findViewById<TextView>(R.id.textView)


    textView.text=item
}
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<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="409dp"
        android:layout_height="729dp"
        android:layout_marginStart="20dp"
        android:layout_marginTop="20dp"
        android:layout_marginEnd="20dp"
        android:layout_marginBottom="13dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

item_list.xml

<?xml version="1.0" encoding="utf-8"?>
<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="wrap_content">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="TextView"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

运行效果