在RecyclerView
适配器中为项目创建单击侦听器的正确方法是什么? This tutorial说它应该在onBindViewHolder
完成,但其他人在onCreateViewHolder
说,我没有看到后者的任何教程因此我感到困惑。
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()
}
}
}
在科特林
在Kotlin中,您无法直接在ViewHolderClass中实现onClickListener。在Kotlin中实现同样的目标,你必须在onBindViewHolder
中做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
只要数据发生变化,就会执行onBindViewHolder
。所以在onClickListener
写ViewHolderClass
是好的。
myButton.setOnClickListener {
//do your stuff here
}
正确的方法是使其以最简单的形式工作。
你能否从onCreateViewHolder
“提前”分配听众,如果是这样,为什么不呢?
考虑onBindViewHolder
将被重复执行的事实。
除非您在创建视图后获得影响视图的新数据,否则没有理由在“执行期间”从经常性的onBindViewHolder
调用中更改您的侦听器。
当您的视图出现在屏幕上时,将始终调用onBindViewHolder()
,以便更多地调用您的项目。滚动时,您将创建许多重复的侦听器。在ViewHolder中设置监听器将为每个持有者创建一个监听器。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)
}
}
}
}