java - 如何在 RecyclerView 中居中选定项目 - Kotlin

Question

我正在尝试将 RecyclerView 中的选定项目居中

我有来自 Fragment 的代码来调用 API 接口和 recyclerView

val recyclerView3: RecyclerView = view.findViewById(R.id.list_recycler3)
    recyclerView3.layoutManager = LinearLayoutManager(
        requireContext(),
        LinearLayoutManager.HORIZONTAL,
        false


    )
val findercatService = findercatService.create().getServices()
    findercatService.enqueue(object : Callback<List<ilmcategoriesData>> {
        override fun onResponse(
            call: Call<List<ilmcategoriesData>>?,
            response: Response<List<ilmcategoriesData>>?
        ) {
            var list = response?.body()!!
            val arrayList = ArrayList<ilmcategoriesData>()
            arrayList.addAll(list)
            list = arrayList



            recyclerView3.adapter =
                ilmcategoriesAdapter(
                    list,
                    MainActivity(),
                    object : ilmcategoriesAdapter.OnClickRecyclerChild {
                        override fun myCallback(s: String?) {

                            

                            when (s.toInt()) {
                                26 -> {
                                    AppPreferences.heightInCentimeters =
                                        1; AppPreferences.birthdayInMilliseconds = "none"
                                }
                                27 -> {
                                    AppPreferences.heightInCentimeters =
                                        2; AppPreferences.birthdayInMilliseconds = "none"
                                }
                                28 -> {
                                    AppPreferences.heightInCentimeters =
                                        3; AppPreferences.birthdayInMilliseconds = "none"
                                }
                                29 -> {
                                    AppPreferences.heightInCentimeters =
                                        4; AppPreferences.birthdayInMilliseconds = "none"
                                }
                                30 -> {
                                    AppPreferences.heightInCentimeters =
                                        5; AppPreferences.birthdayInMilliseconds = "none"
                                }
                                31 -> {
                                    AppPreferences.heightInCentimeters =
                                        6; AppPreferences.birthdayInMilliseconds = "none"
                                }
                                32 -> {
                                    AppPreferences.heightInCentimeters =
                                        7; AppPreferences.birthdayInMilliseconds = "none"
                                }
                                33 -> {
                                    AppPreferences.heightInCentimeters =
                                        8; AppPreferences.birthdayInMilliseconds = "none"
                                }
                                34 -> {
                                    AppPreferences.heightInCentimeters =
                                        9; AppPreferences.birthdayInMilliseconds = "none"
                                }
                                35 -> {
                                    AppPreferences.heightInCentimeters =
                                        10; AppPreferences.birthdayInMilliseconds = "none"
                                }
                                36 -> {
                                    AppPreferences.heightInCentimeters =
                                        11; AppPreferences.birthdayInMilliseconds = "none"
                                }
                                37 -> {
                                    AppPreferences.heightInCentimeters =
                                        12; AppPreferences.birthdayInMilliseconds = "none"
                                }
                                38 -> {
                                    AppPreferences.heightInCentimeters =
                                        13; AppPreferences.birthdayInMilliseconds = "none"
                                }
                                39 -> {
                                    AppPreferences.heightInCentimeters =
                                        14; AppPreferences.birthdayInMilliseconds = "none"
                                }


                                else -> { // Note the block
                                    AppPreferences.heightInCentimeters = 0
                                }
                            }

                            
                            if (AppPreferences.birthdayInMilliseconds == "fav") {
                                getToken()
                                val finderService = finderService.create().getServices(token)
                                finderService.enqueue(object : Callback<List<IlmFinders>> {
                                    override fun onResponse(
                                        call: Call<List<IlmFinders>>?,
                                        response: Response<List<IlmFinders>>?

                                    ) {

                                        if (response != null) {

                                            if (response.isSuccessful) {
                                                val arrayList = ArrayList<IimfinderData>()
                                                val allfinders = response.body()?.get(0)
                                                for (fav in allfinders?.ilmFinders!!) {
                                                    if (fav.isFavourite)
                                                        arrayList.add(fav)
                                                }
                                                Log.d(
                                                    TAG,
                                                    "onResponse: favorite size = ${arrayList.size}"
                                                )
                                                var newAdapter =
                                                    FavoriteAdapter(
                                                        arrayList,
                                                        MainActivity()
                                                    )

                                                recyclerView6.adapter =
                                                    newAdapter

                                                newAdapter.notifyDataSetChanged()
                                            }

                                        }


                                    }

                                    override fun onFailure(
                                        call: Call<List<IlmFinders>>?,
                                        t: Throwable?
                                    ) {
                                        
                                    }
                                })
                            } else {
                                val finderService = finderService.create().getServices()
                                finderService.enqueue(object : Callback<List<IlmFinders>> {
                                    override fun onResponse(
                                        call: Call<List<IlmFinders>>?,
                                        response: Response<List<IlmFinders>>?
                                    ) {

                                        val list = response?.body()!!
                                        val newAdapter =
                                            IimfinderAdapter(list, MainActivity())

                                        recyclerView6.adapter =
                                            IimfinderAdapter(list, MainActivity())


                                        newAdapter.notifyDataSetChanged()
                                    }

                                    override fun onFailure(
                                        call: Call<List<IlmFinders>>?,
                                        t: Throwable?
                                    ) {
                                        
                                    }
                                })
                            }

                        }
                    })
        }

        override fun onFailure(call: Call<List<ilmcategoriesData>>?, t: Throwable?) {
      
        }
    })

适配器：

class ilmcategoriesAdapter(
var countryList: List<ilmcategoriesData>,
var activity: MainActivity,

var listener: OnClickRecyclerChild
) : RecyclerView.Adapter<ilmcategoriesAdapter.ViewHolder>() {
var prevIndex = -1


init {
    val arrayList = ArrayList<ilmcategoriesData>()
    arrayList.addAll(countryList)
    arrayList.add(0, ilmcategoriesData(41, "All Categories"))
    arrayList.add(1, ilmcategoriesData(42, "Favorite"))
    countryList = arrayList
}

lateinit var context: Context

override fun onCreateViewHolder(
    parent: ViewGroup,
    viewType: Int
): ViewHolder {
    context = parent.context!!
    val view = LayoutInflater.from(context).inflate(R.layout.list_item3, parent, false)
    return ViewHolder(view)

}

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

override fun onBindViewHolder(holder: ViewHolder, position: Int) {
    holder.eventName.text = countryList[position].name

    holder.eventName.setOnClickListener {
        notifyDataSetChanged()
        prevIndex = position
        var CategoryID = countryList[position].id
        var CategoryIdStr = CategoryID.toString()


        when (CategoryID) {
            41 -> {
                AppPreferences.birthdayInMilliseconds = "all"
            }
            42 -> {
                AppPreferences.birthdayInMilliseconds = "fav"
            }
            else -> AppPreferences.birthdayInMilliseconds = "none"
        }



        listener.myCallback(CategoryIdStr)


        if (position == prevIndex) {

            holder.eventName.background =
                ContextCompat.getDrawable(context, R.drawable.iimfinder_selector)
            holder.eventName.setTypeface(null, Typeface.BOLD)
        } else {
            holder.eventName.background = ContextCompat.getDrawable(context, R.color.white)
            holder.eventName.setTypeface(null, Typeface.NORMAL)
        }
    }

    if (position == prevIndex) {
        holder.eventName.setTypeface(null, Typeface.BOLD)
        holder.eventName.background =
            ContextCompat.getDrawable(context, R.drawable.iimfinder_selector)
    }
    else if(position == 0) {
        holder.eventName.setTypeface(null, Typeface.BOLD)
        holder.eventName.background =
            ContextCompat.getDrawable(context, R.drawable.iimfinder_selector)
    }
    else {
        holder.eventName.setTypeface(null, Typeface.NORMAL)
        holder.eventName.background = ContextCompat.getDrawable(context, R.color.white)
    }

}

class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
    val eventName: TextView = itemView.findViewById(R.id.cat_title)


}


interface OnClickRecyclerChild {
    fun myCallback(s: String?)


}



}

从 API 显示这些项目，一旦用户点击一个项目，该项目将自动在屏幕中居中

我试图在片段中添加 snaphelper 但它不起作用

标签： javaandroidapikotlinandroid-recyclerview