RecyclerView学习之应用

代码
RecyclerView.ViewHolder
RecyclerView.Adapater

getItemCount
getItemViewType
onCreateViewHolder
onBindViewHolder

RecyclerView应用

LinearLayoutManager

VERTICAL
HORIZONTAL

GridLayoutManager
StaggeredGridLayoutManager

学而不思则罔，思而不学则殆

相关文档：
RecyclerView学习（一）之应用
RecyclerView学习（二）之缓存探索
RecyclerView学习（三）之缓存原理分析
平时项目中使用RecyclerView机会特别多，列表展示是很好的工具，本篇文章就先来讲解一些使用心得，可能会不全，但是会慢慢增加他的使用方法

代码

https://github.com/aJanefish/RecyclerViewStudy

RecyclerView.ViewHolder

ViewHolder 是视图的载体，设计到数据绑定，视图展示，复用等功能

//用Kotlin实现    class TestHolder(itemView: View) : ViewHolder(itemView) {        //findViewById 获取View,在复用的时候就不用每次都去findView,增加开销        private val mTitle: TextView = itemView.findViewById(R.id.activity_study_one_item_tv)        //... 更多View        // 数据对象        private var mBean: Bean? = null              //绑定数据        fun onBind(bean: Bean?) {            if (bean == null) {                return            }            //数据操作，视图展示等            mBean = bean            mTitle.text = mBean?.mTitle ?: "我是小可爱"            mIndex.text = mBean?.index.toString() ?: "我是小可爱"            mDes.text = "$lastPosition -> $newPosition"            mImageView.setImageResource(mBean!!.imageId)            lastPosition = newPosition        }        init {        //对象初始化操作等        }    }

RecyclerView.Adapater

Adapater非常重要，是数据和RecyclerVeiw之间的桥梁，主要有几个方法比较重要
整体结构如下

class StudyOneAdapter(list: List<Bean?>) : RecyclerView.Adapter<StudyOneAdapter.TestHolder>() {    private val sTAG = "zy.StudyOneAdapter"    private var mList: List<Bean?> = mutableListOf<Bean?>()    init {        mList = list    }    //创建Holder    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): TestHolder {...}    //绑定数据，如果有复用会直接返回复用的Holder    override fun onBindViewHolder(holder: TestHolder, position: Int) {...}    //返回数据个数，会根据这个生成视图    override fun getItemCount(): Int {...}    //返回ItemType,用来展示不同的是同一个RecyclerView，最常见的就是对话形式的展示    override fun getItemViewType(position: Int): Int {...}    class TestHolder(itemView: View) : ViewHolder(itemView) {...}    //数据类    class Bean(val index: Int, val imageId: Int, val mTitle: String, val itemType: Int = 0)}

getItemCount

返回数据个数，会根据这个生成视图

    override fun getItemCount(): Int {        return mList.size    }

getItemViewType

返回ItemType,用来展示不同的是同一个RecyclerView，最常见的就是对话形式的展示，一左一右两种不同的View

    //根据数据不同得到不同的type    override fun getItemViewType(position: Int): Int {        return mList[position]?.itemType ?: 0    }

onCreateViewHolder

创建Holder

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): TestHolder {        Log.d(sTAG, "onCreateViewHolder")        mCreateNum++        val view = LayoutInflater.from(parent.context).inflate(R.layout.activity_study_one_item, parent, false)        when (viewType) {            0 -> return TestHolder1(view)            1 -> return TestHolder2(view)            else -> return TestHolder3(view)        }    }

onBindViewHolder

绑定数据，如果有复用会直接返回复用的Holder

    override fun onBindViewHolder(holder: TestHolder, position: Int) {        holder.onBind(mList[position])    }

RecyclerView应用

LinearLayoutManager

线性流展示

VERTICAL

val recyclerView = findViewById<RecyclerView>(R.id.test_rv)recyclerView.layoutManager = LinearLayoutManager(context) //默认是竖直视图+mReverseLayout = falserecyclerView.layoutManager = LinearLayoutManager(context, RecyclerView.VERTICAL, false)recyclerView.layoutManager = LinearLayoutManager(context, RecyclerView.VERTICAL, true)

HORIZONTAL

val recyclerView = findViewById<RecyclerView>(R.id.test_rv)recyclerView.layoutManager = LinearLayoutManager(context, RecyclerView.HORIZONTAL, false)recyclerView.layoutManager = LinearLayoutManager(context, RecyclerView.HORIZONTAL, true)

GridLayoutManager

表格流视图

val recyclerView = findViewById<RecyclerView>(R.id.test_rv)recyclerView.layoutManager = GridLayoutManager(context, 3, GridLayoutManager.HORIZONTAL, false)recyclerView.layoutManager = GridLayoutManager(context, 3, GridLayoutManager.HORIZONTAL, true)recyclerView.layoutManager = GridLayoutManager(context, 3, GridLayoutManager.VERTICAL, false)recyclerView.layoutManager = GridLayoutManager(context, 3, GridLayoutManager.VERTICAL, true)

StaggeredGridLayoutManager

瀑布流视图

val recyclerView = findViewById<RecyclerView>(R.id.test_rv)recyclerView.layoutManager = StaggeredGridLayoutManager(3,StaggeredGridLayoutManager.HORIZONTAL)recyclerView.layoutManager = StaggeredGridLayoutManager(3,StaggeredGridLayoutManager.VERTICAL)

RecyclerView学习（一）之应用