Android RecyclerView AsyncListDiffer DiffUtil,Kotlin(b)

Android RecyclerView AsyncListDiffer DiffUtil,Kotlin(b)

Kotlin 复制代码
import android.graphics.Color
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
import androidx.recyclerview.widget.AsyncListDiffer
import androidx.recyclerview.widget.DiffUtil
import androidx.recyclerview.widget.GridLayoutManager
import androidx.recyclerview.widget.RecyclerView
import java.util.UUID
import kotlin.random.Random

const val ITEM_COUNT = 30

class MainActivity : AppCompatActivity() {
    private var mAdapter: MyAdapter? = null

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

        val rv = findViewById<RecyclerView>(R.id.rv)
        val layoutManager = GridLayoutManager(this, 3)
        rv.layoutManager = layoutManager

        mAdapter = MyAdapter()
        rv.adapter = mAdapter
    }

    override fun onResume() {
        super.onResume()

        val newList = mutableListOf<MyItem>()
        for (i in 0 until ITEM_COUNT) {
            val item = MyItem()
            item.pos = i
            item.change = Random.Default.nextBoolean()
            item.data = System.currentTimeMillis()
            item.contentId = UUID.randomUUID()
            newList.add(item)
        }
        mAdapter?.onChange(newList)
    }

    class MyAdapter : RecyclerView.Adapter<MyVH> {
        private val mDiffer = AsyncListDiffer(this, object : DiffUtil.ItemCallback<MyItem>() {
            override fun areItemsTheSame(oldItem: MyItem, newItem: MyItem): Boolean {
                return oldItem.pos == newItem.pos
            }

            override fun areContentsTheSame(oldItem: MyItem, newItem: MyItem): Boolean {
                return oldItem.contentId == newItem.contentId
            }

            override fun getChangePayload(oldItem: MyItem, newItem: MyItem): Any? {
                return super.getChangePayload(oldItem, newItem)
            }
        })

        constructor() {
            val list = mutableListOf<MyItem>()
            for (i in 0 until ITEM_COUNT) {
                val item = MyItem(i)
                item.data = 0L
                item.change = false
                list.add(item)
            }

            onChange(list)
        }

        fun onChange(list: MutableList<MyItem>) {
            mDiffer.submitList(list)
        }

        override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyVH {
            val view = LayoutInflater.from(parent.context).inflate(android.R.layout.simple_list_item_2, parent, false)
            return MyVH(view)
        }

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

        override fun onBindViewHolder(holder: MyVH, position: Int) {
            holder.text1.text = "pos=${mDiffer.currentList[position].pos}"
            holder.text2.text = "data=${mDiffer.currentList[position].data}"

            if (mDiffer.currentList[position].change) {
                holder.text1.setTextColor(Color.RED)
                holder.text2.setTextColor(Color.RED)
            } else {
                holder.text1.setTextColor(Color.BLACK)
                holder.text2.setTextColor(Color.BLACK)
            }
        }
    }

    class MyVH(itemView: View) : RecyclerView.ViewHolder(itemView) {
        val text1: TextView = itemView.findViewById(android.R.id.text1)
        val text2: TextView = itemView.findViewById(android.R.id.text2)
    }

    class MyItem {
        var pos = 0
        var data = 0L
        var contentId = UUID.randomUUID()
        var change = false

        constructor(pos: Int) {
            this.pos = pos
        }

        constructor() : this(0) {
        }
    }
}
相关推荐
Propeller27 分钟前
【Android】View 交互的事件处理机制
android·java
吴Wu涛涛涛涛涛Tao29 分钟前
Flutter 实现「可拖拽评论面板 + 回复输入框 + @高亮」的完整方案
android·flutter·ios
小孔龙31 分钟前
02.Kotlin Serialization 属性序列化控制
kotlin·json
雨声不在33 分钟前
使用android studio分析cpu开销
android·ide·android studio
程序leo源2 小时前
Linux_基础指令(二)
android·linux·运维·服务器·青少年编程
雨白4 小时前
Android 两种拖拽 API 详解:ViewDragHelper 和 OnDragListener 的原理与区别
android
元亓亓亓4 小时前
JavaWeb--day3--Ajax&Element&路由&打包部署
android·ajax·okhttp
居然是阿宋4 小时前
Android XML属性与Jetpack Compose的对应关系(控件基础属性篇)
android
GoatJun4 小时前
Android ScrollView嵌套RecyclerView 导致RecyclerView数据展示不全问题
android