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
