Question

在RecyclerView适配器中为项目创建点击侦听器的正确方法是什么？ This tutorial说应该在onBindViewHolder中完成，但是其他人在onCreateViewHolder中说过，而且我还没有看到任何有关后者的教程，因此感到困惑。

class MyRVAdapter(private val myList: ArrayList<Item>) : RecyclerView.Adapter<MyRVAdapter.ViewHolder>() {
    override fun getItemCount(): Int {
        return myList.size
    }

    class ViewHolder (itemView : View):RecyclerView.ViewHolder(itemView) {
        // val myButton = itemView.findViewById<Button>(R.id.btn_A)!!
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        holder.myButton.text = (myList[position].btnTitle)
     }

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

        val myButton = v.findViewById<Button>(R.id.btn_A)!!

        myButton.setOnClickListener {
            customView = View.inflate(holder.itemView.context, R.layout.fragment_dialog, null)

                val builder = AlertDialog.Builder(holder.itemView.context)
                builder.setIconAttribute(R.attr.imgInfo)
                builder.setTitle(R.string.dialog_title)
                builder.setView(customView)
                builder.setPositiveButton(android.R.string.ok){ dialog, _ -> dialog.dismiss() }
                builder.show()
        }
    }
}

Answer 1

正确的方法是使其以最简单的形式工作。
您可以从onCreateViewHolder分配侦听器“提前”吗？如果可以，为什么不呢？
考虑一下onBindViewHolder将被重复执行的事实。
除非在创建视图持有者之后获得新的数据，否则将没有理由在循环onBindViewHolder调用中更改“在执行期间”的侦听器。

Answer 2

在科特林

在Kotlin中，您不能直接在ViewHolderClass中实现onClickListener。在Kotlin中要实现相同的目的，您必须在onBindViewHolder

内执行onClickListener

holder.myButton.setOnClickListener {
            //do your stuff here
}

或使用init函数

// I'm not sure this is a correct method or not

class MyRVAdapter : RecyclerView.Adapter<MyRVAdapter.ViewHolder>() {


    override fun getItemCount(): Int {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }


    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }


    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyRVAdapter.ViewHolder {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }

    class ViewHolder(itemView: View): RecyclerView.ViewHolder(itemView) {
        var myButton = itemView.findViewById(R.id.button) as Button

         // use any of the following declaratons
         // val myButton = itemView.findViewById(R.id.button) as Button
         // val myButton = itemView.findViewById<Button>(R.id.button)
         // var myButton = itemView.findViewById<Button>(R.id.button)
         // var myButton:Button = itemView.findViewById(R.id.button)
         // val myButton:Button = itemView.findViewById(R.id.button)


        // to avoid Expecting Member Declaration is showing in kotlin  use constructor
       // Expecting Member Declaration is showing because kotlin allows null declaration so a constructor or init is required to avoid this
        init {
            myButton.setOnClickListener{
                //do your stuff here
            }
        }

    }
}

在Java中

onBindViewHolder将在数据发生更改时执行。因此，最好将onClickListener写在ViewHolderClass中。

myButton.setOnClickListener {
            //do your stuff here
}

Answer 3

onBindViewHolder()会在您的“视图”出现在屏幕上时始终被调用，因此它的调用次数超过了项目数。滚动时，您将创建很多重复的侦听器。在ViewHolder中设置侦听器将为每个所有者创建一个侦听器。这是代码：

class MyRVAdapter() : RecyclerView.Adapter<MyRVAdapter.ViewHolder>() {

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        holder.myButton.text = "set here all except listener"
    }

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

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

    class ViewHolder (itemView: View) : RecyclerView.ViewHolder(itemView) {

        var myButton: Button = itemView.findViewById(R.id.btn_A)

        init {
            myButton.setOnClickListener {
                val customView = View.inflate(itemView.context, R.layout.fragment_dialog, null)

                val builder = AlertDialog.Builder(itemView.context)
                builder.setIconAttribute(R.attr.imgNight)
                builder.setTitle(R.string.dialog_title)
                builder.setView(customView)
                builder.setPositiveButton(android.R.string.ok){ dialog, _ -> dialog.dismiss() }
                builder.show()

                val tabLayout = customView.findViewById(R.id.mTabLayout)
                val viewPager = customView.findViewById(R.id.mViewPager)

                val adapter = TabbedDialogAdapter(childFragmentManager)//i dont understand how you get this but it is another question
                adapter.addFragment("Tab A", TabbedDialogFragment.createInstance("Description A"))
                adapter.addFragment("Tab B", TabbedDialogFragment.createInstance("Description B"))
                adapter.addFragment("Tab C", TabbedDialogFragment.createInstance("Description C"))

                viewPager.adapter = adapter
                tabLayout.setupWithViewPager(viewPager)
            }
        }
    }
}

正确实现RecyclerView适配器的Click侦听器

3 个答案: