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
爬虫程序猿8 小时前
利用爬虫按关键字搜索淘宝商品实战指南
android·爬虫
顾北川_野8 小时前
Android ttyS2无法打开该如何配置 + ttyS0和ttyS1可以
android·fpga开发
wzj_what_why_how11 小时前
Android网络层架构:统一错误处理的问题分析到解决方案与设计实现
android·架构
千里马学框架12 小时前
User手机上如何抓取界面的布局uiautomatorviewer
android·智能手机·aosp·uiautomator·布局抓取·user版本
阿巴~阿巴~12 小时前
操作系统核心技术剖析:从Android驱动模型到鸿蒙微内核的国产化实践
android·华为·harmonyos
hsx66613 小时前
使用 MaterialShapeDrawable 自定义各种形状的 View
android
用户20187928316713 小时前
滑动城堡的奇妙管家 ——ViewPager故事
android
用户20187928316713 小时前
📜 童话:魔法卷轴与 ScrollView 的奥秘
android
hsx66614 小时前
Kotlin 协程中的 Dispatchers
kotlin
??? Meggie15 小时前
【SQL】使用UPDATE修改表字段的时候,遇到1054 或者1064的问题怎么办?
android·数据库·sql