class DiffCallBack(val oldList: ArrayList<Person>, val newList: ArrayList<Person>) :DiffUtil.Callback() {

    //判斷兩個(gè)對(duì)象是否相同
    override fun areItemsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
        
        return oldList[oldItemPosition].id == newList[newItemPosition].id
    }

    override fun getOldListSize(): Int {
        return oldList.size
    }

    override fun getNewListSize(): Int {
        return newList.size
    }

    //判斷兩個(gè)對(duì)象內(nèi)容是否相同
    override fun areContentsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
        val newItem = newList[newItemPosition]
        val oldItem = oldList[oldItemPosition]

        //如果新數(shù)據(jù)和舊數(shù)據(jù)的名稱和年齡相同,則視為兩個(gè)item的內(nèi)容相同
        return oldItem.age == newItem.age && oldItem.name == newItem.name
    }

}

val oldList = adapter.getData()
//深拷貝oldList得到newList,然后對(duì)newList按照業(yè)務(wù)進(jìn)行增刪改的操作,這里代碼就省略了..

//計(jì)算不同之處
val diffResult = DiffUtil.calculateDiff(DiffCallBack(oldList,newList))
//adapter設(shè)置新數(shù)據(jù)
adapter.setData(newList)
//將變更操作分發(fā)給adapter
diffResult.dispatchUpdatesTo(adapter)

class RvAdapter() : ListAdapter<Person, RvAdapter.ViewHolder>(diffCallback) {

    companion object {
        val diffCallback = object : DiffUtil.ItemCallback<Person>() {
            override fun areItemsTheSame(oldItem: Person, newItem: Person): Boolean {
                return oldItem.id == newItem.id
            }

            override fun areContentsTheSame(oldItem: Person, newItem: Person): Boolean {
                //如果新數(shù)據(jù)和舊數(shù)據(jù)的名稱和年齡相同,則視為兩個(gè)item的內(nèi)容相同
                return oldItem.age == newItem.age && oldItem.name == newItem.name
            }

        }
    }

    class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
        var tvAge: TextView = itemView.findViewById(R.id.tvAge)
        var tvName: TextView = itemView.findViewById(R.id.tvUserName)
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val itemView = View.inflate(parent.context, R.layout.rv_item_person, null)
        return ViewHolder(itemView)
    }


    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        val item = getItem(position)
        holder.tvName.text = item.name
        holder.tvAge.text = item.age.toString()
    }
}

val oldList = adapter.currentList

val newList = oldList.map { it }.toMutableList()
newList.removeAt(10)
//下標(biāo)2加個(gè)新數(shù)據(jù)
newList.add(2, Person(90, "我的", 72))
adapter.submitList(list)