我有一個 RecyclerView 并且我試圖將位置從我的配接器傳遞回主要活動，但到目前為止沒有成功?。
我認為配接器中的代碼正在將資料傳回作業，但不幸的是我無法弄清楚如何在 MainActivity 的 onCreate 中設定初始化作業？我不確定如何使用“ lazy ”（即 mainactivity 中的“private val itemAdapter by lazy”）來呼叫它？
我對解決此問題感到沮喪，因此感謝任何幫助。
主活動.kt
class MainActivity : AppCompatActivity(), ItemAdapter.OnItemClickListener {
private val itemAdapter by lazy {
ItemAdapter { position: Int, item: Item ->
Toast.makeText(this@MainActivity, "Pos ${position}", Toast.LENGTH_LONG).show()
item_list.smoothScrollToPosition(position)
} }
private val possibleItems = listOf(
Item("Plane 1", R.drawable.ic_airplane),
Item("Car 2", R.drawable.ic_car),
Item("Meals 3", R.drawable.ic_food),
Item("Fuel 4", R.drawable.ic_gas),
Item("Home 5 ", R.drawable.ic_home)
)
fun onImageClick(imageData: String?) {
// handle image data
}
override fun onCreate(savedInstanceState: Bundle?) {
var position: Int
val thisitem: Item
var thisunit: Unit
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
// var itemAdapter = ItemAdapter(possibleItems)
// var thisitemAdapter = ItemAdapter((position, thisitem) -> thisunit)
// Toast.makeText(this@MainActivity, "Pos ${position}", Toast.LENGTH_LONG).show()
// item_list.smoothScrollToPosition(position) //CAN'T GET THIS TO COMPILE
item_list.initialize(itemAdapter)
itemAdapter.setOnItemClickListener(this) // Added this
ItemSnapHelper().attachToRecyclerView(item_list)
item_list.setViewsToChangeColor(listOf(R.id.list_item_background, R.id.list_item_text))
item_list.scrollToPosition(Int.MAX_VALUE/2)
itemAdapter.setItems(possibleItems)
}
override
public fun getAdapterPosition(position : Int ){
Toast.makeText(this,"this is toast message" position,Toast.LENGTH_SHORT).show()
}
private fun getLargeListOfItems(): List<Item> {
val items = mutableListOf<Item>()
(0..40).map { items.add(possibleItems.random()) }
return items
}
}
data class Item(
val title: String,
@DrawableRes val icon: Int
)
專案配接器.kt
class ItemAdapter(val itemClick: (position:Int,item:Item) -> Unit) : RecyclerView.Adapter<ItemViewHolder>() {
private var items: List<Item> = listOf()
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ItemViewHolder =
ItemViewHolder(LayoutInflater.from(parent.context).inflate(R.layout.list_item, parent, false))
override fun onBindViewHolder(holder: ItemViewHolder, position: Int) {
val pos = position % items.size
holder.bind(items[pos]) // bind the actual item
Log.d("xx position= ", pos.toString())
}
override fun getItemCount(): Int = Int.MAX_VALUE
fun setItems(newItems: List<Item>) {
items = newItems
notifyDataSetChanged()
}
lateinit var listener: OnItemClickListener
public interface OnItemClickListener {
fun getAdapterPosition(position : Int )
}
public fun setOnItemClickListener(listener: OnItemClickListener) {
this.listener= listener
}
}
class ItemViewHolder(private val view: View) : RecyclerView.ViewHolder(view) {
fun bind(item: Item) {
view.list_item_text.text = "${item.title}"
view.list_item_icon.setImageResource(item.icon)
}
}
uj5u.com熱心網友回復：
你有一個聽眾，所以你可以這樣寫
class MainActivity : AppCompatActivity(), ItemAdapter.OnItemClickListener {
private lateinit var itemAdapter: ItemAdapter
private val possibleItems = listOf(
Item("Plane 1", R.drawable.ic_airplane),
Item("Car 2", R.drawable.ic_car),
Item("Meals 3", R.drawable.ic_food),
Item("Fuel 4", R.drawable.ic_gas),
Item("Home 5 ", R.drawable.ic_home)
)
fun onImageClick(imageData: String?) {
// handle image data
}
override fun onCreate(savedInstanceState: Bundle?) {
var position: Int
val thisitem: Item
var thisunit: Unit
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
itemAdapter = ItemAdapter()
itemAdapter.listener = this
item_list.initialize(itemAdapter)
ItemSnapHelper().attachToRecyclerView(item_list)
item_list.setViewsToChangeColor(listOf(R.id.list_item_background, R.id.list_item_text))
item_list.scrollToPosition(Int.MAX_VALUE/2)
itemAdapter.setItems(possibleItems)
}
override
public fun getAdapterPosition(position : Int ){
Toast.makeText(this,"this is toast message" position,Toast.LENGTH_SHORT).show()
}
private fun getLargeListOfItems(): List<Item> {
val items = mutableListOf<Item>()
(0..40).map { items.add(possibleItems.random()) }
return items
}
}
專案配接器.kt
class ItemAdapter : RecyclerView.Adapter<ItemViewHolder>() {
private var items: List<ClipData.Item> = listOf()
var listener: OnItemClickListener? = null
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ItemViewHolder = ItemViewHolder(LayoutInflater.from(parent.context).inflate(R.layout.list_item, parent, false))
override fun onBindViewHolder(holder: ItemViewHolder, position: Int) {
holder.bind(items[position], position)
}
override fun getItemCount(): Int = Int.MAX_VALUE
fun setItems(newItems: List<ClipData.Item>) {
items = newItems
notifyDataSetChanged()
}
}
class ItemViewHolder(val view: View) : RecyclerView.ViewHolder(view) {
fun bind(item: ClipData.Item, position: Int) {
view.list_item_text.text = "${item.title}"
view.list_item_icon.setImageResource(item.icon)
view.list_item_text.setOnClickListener {
listener?.getAdapterPosition(position)
}
}
}
interface OnItemClickListener {
fun getAdapterPosition(position: Int)
}
uj5u.com熱心網友回復：
您還可以將 lambda 函式作為回呼傳遞給配接器，而不是創建介面。
基本結構將是這樣的：
class MainActivity: AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
...
val itemAdapter = ItemAdapter { position ->
// do whatever you wish with this position
}
recyclerView.adapter = itemAdapter
...
}
}
class ItemAdapter(private val onClick: (Int) -> Unit) {
...
inner class ItemViewHolder(val view: View) : RecyclerView.ViewHolder(view) {
fun bind(item: ClipData.Item, position: Int) {
...
view.setOnClickListener {
onClick(position)
}
}
}
}
如果您不想創建ItemViewHolder為內部類，則可以onClick在其建構式中接受lambda 并將其從onCreateViewHolder.
轉載請註明出處，本文鏈接：https://www.uj5u.com/qianduan/357549.html