Kotlin中的RecyclerView itemClickListener [英] RecyclerView itemClickListener in Kotlin
问题描述
经过3年的Android使用经验，我正在Kotlin编写我的第一个应用程序. 只是对如何在Kotlin中将itemClickListener与RecyclerView一起使用感到困惑.
我已经尝试过特质(edit:now interface)方法，非常类似于Java
public class MainActivity : ActionBarActivity() {
protected override fun onCreate(savedInstanceState: Bundle?) {
// set content view etc go above this line
class itemClickListener : ItemClickListener {
override fun onItemClick(view: View, position: Int) {
Toast.makeText(this@MainActivity, "TEST: " + position, Toast.LENGTH_SHORT).show()
}
}
val adapter = DrawerAdapter(itemClickListener())
mRecyclerView.setAdapter(adapter)
}
trait ItemClickListener {
fun onItemClick(view: View, position: Int)
}
}
这似乎很多余，所以我尝试了内部类方法:
inner class ItemClickListener {
fun onItemClick(view: View, position: Int) {
startActivityFromFragmentForResult<SelectExerciseActivity>(SELECT_EXERCISES)
}
}
然后像这样设置适配器的点击监听器:
val adapter = WorkoutsAdapter(ItemClickListener())
但是我对此仍然不满意，因为我认为可能会有更好，更清洁的方法.我试图从根本上实现这样的事情: RecyclerView onClick
有什么建议吗?
最终得到了批准答案的变体
在活动中定义功能:
val itemOnClick: (View, Int, Int) -> Unit = { view, position, type ->
Log.d(TAG, "test")
}
将函数本身传递给适配器，如下所示:
class ExercisesAdapter(val itemClickListener: (View, Int, Int) -> Unit) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
// other stuff up here
val vhExercise = ExerciseVH(view) // view holder
// on to the view holder through the extension function
vhExercise.onClick(itemClickListener)
}
}
在下面批准的答案中通过循环扩展功能.
fun <T : RecyclerView.ViewHolder> T.onClick(event: (view: View, position: Int, type: Int) -> Unit): T {
itemView.setOnClickListener {
event.invoke(it, getAdapterPosition(), getItemViewType())
}
return this
}
我有一些不同的方法.您可以为ViewHolder创建扩展名
fun <T : RecyclerView.ViewHolder> T.listen(event: (position: Int, type: Int) -> Unit): T {
itemView.setOnClickListener {
event.invoke(getAdapterPosition(), getItemViewType())
}
return this
}
然后像这样在适配器中使用它
class MyAdapter : RecyclerView.Adapter<MyAdapter.MyViewHolder>() {
val items: MutableList<String> = arrayListOf()
override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): MyViewHolder? {
val inflater = LayoutInflater.from(parent!!.getContext())
val view = inflater.inflate(R.layout.item_view, parent, false)
return MyViewHolder(view).listen { pos, type ->
val item = items.get(pos)
//TODO do other stuff here
}
}
override fun onBindViewHolder(holder: MyViewHolder?, position: Int) {
}
override fun getItemCount(): Int {
return items.size()
}
class MyViewHolder(view: View) : RecyclerView.ViewHolder(view) {
}
}
我正在与同事一起在图书馆中提供此类扩展名. >
I'm writing my first app in Kotlin after 3 years of experience with Android. Just confused as to how to utilize itemClickListener with a RecyclerView in Kotlin.
I have tried the trait (edit: now interface) approach, very Java-like
public class MainActivity : ActionBarActivity() {
protected override fun onCreate(savedInstanceState: Bundle?) {
// set content view etc go above this line
class itemClickListener : ItemClickListener {
override fun onItemClick(view: View, position: Int) {
Toast.makeText(this@MainActivity, "TEST: " + position, Toast.LENGTH_SHORT).show()
}
}
val adapter = DrawerAdapter(itemClickListener())
mRecyclerView.setAdapter(adapter)
}
trait ItemClickListener {
fun onItemClick(view: View, position: Int)
}
}
That seemed very redundant so I tried the inner class approach:
inner class ItemClickListener {
fun onItemClick(view: View, position: Int) {
startActivityFromFragmentForResult<SelectExerciseActivity>(SELECT_EXERCISES)
}
}
And then just setting the adapter's click listener like this:
val adapter = WorkoutsAdapter(ItemClickListener())
But I'm still not satisfied with this because I think there might be a better, cleaner way. I'm trying to essentially achieve something like this: RecyclerView onClick
Any suggestions?
Ended up going with a variation of the approved answer
Defined the function in the activity:
val itemOnClick: (View, Int, Int) -> Unit = { view, position, type ->
Log.d(TAG, "test")
}
Passed the function itself on to the adapter like this:
class ExercisesAdapter(val itemClickListener: (View, Int, Int) -> Unit) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
// other stuff up here
val vhExercise = ExerciseVH(view) // view holder
// on to the view holder through the extension function
vhExercise.onClick(itemClickListener)
}
}
Extension function by Loop in the approved answer below.
fun <T : RecyclerView.ViewHolder> T.onClick(event: (view: View, position: Int, type: Int) -> Unit): T {
itemView.setOnClickListener {
event.invoke(it, getAdapterPosition(), getItemViewType())
}
return this
}
I have a little bit different approach. You can create an extension for your ViewHolder
fun <T : RecyclerView.ViewHolder> T.listen(event: (position: Int, type: Int) -> Unit): T {
itemView.setOnClickListener {
event.invoke(getAdapterPosition(), getItemViewType())
}
return this
}
Then use it in adapter like this
class MyAdapter : RecyclerView.Adapter<MyAdapter.MyViewHolder>() {
val items: MutableList<String> = arrayListOf()
override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): MyViewHolder? {
val inflater = LayoutInflater.from(parent!!.getContext())
val view = inflater.inflate(R.layout.item_view, parent, false)
return MyViewHolder(view).listen { pos, type ->
val item = items.get(pos)
//TODO do other stuff here
}
}
override fun onBindViewHolder(holder: MyViewHolder?, position: Int) {
}
override fun getItemCount(): Int {
return items.size()
}
class MyViewHolder(view: View) : RecyclerView.ViewHolder(view) {
}
}
I am working with my colleagues on library providing such extensions.
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