无法为 RecyclerView 项目添加 setOnClickListener

Question

此应用程序使用 sharedPreferences 来填充 MainActivity.kt 中的回收器查看器。然后我想在每个回收器项目中有两个按钮，以便有一个事件侦听器将转到另一个活动。但是我一直无法这样做，试图操纵适配器和 MainActivity.kt。

MainActivity.kt：

import android.app.Activity
import android.content.Context
import android.content.Intent
import android.content.SharedPreferences
import android.os.Bundle
import android.view.View
import androidx.appcompat.app.AppCompatActivity
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import kotlinx.android.synthetic.main.activity_main.*
import java.io.File

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        populateRecycler()



        //Pressing GPS icon will go to adding a new location
        fabAddLocation.setOnClickListener { view -> addLocation(view) }
        }

    fun addLocation(x:View?){
        val locationIntent: Intent = Intent(this,AddLocation::class.java)
        startActivity(locationIntent)
    }

    fun createRecyclerContent(list :Array<String>): ArrayList<LocationItem> {

        //Get the shared preference file data
        var size = list.size
        val itemList = ArrayList<LocationItem>()
        for (i in 0 until size){
            val name = list[i].substring(0, list[i].length -4)
            lateinit var prefs:SharedPreferences

            prefs = getSharedPreferences(name,Context.MODE_PRIVATE)

            val getTitle = prefs.getString("Title","")
            val getDescription = prefs.getString("Description","")
            val getGps = prefs.getString("Longitude","")+","+prefs.getString("Latitude","")
            val listItem = LocationItem(R.drawable.ic_location_icon,getTitle.toString(),getDescription.toString(),getGps)

            itemList += listItem

        }
        return itemList

    }
    fun populateRecycler(){
        val sharedPrefsDir = File(applicationInfo.dataDir, "shared_prefs")
        if(sharedPrefsDir.exists() && sharedPrefsDir.isDirectory()){
            //verifying that the directory is found and that it has the names
            val locateList = sharedPrefsDir.list();
            //This should be sending the number of recycler items to my createRecyclerContent function, to populate the recycler

            val locationsList = createRecyclerContent(locateList)

            recycler_view.adapter=LocationsAdapter(locationsList)
            (recycler_view.adapter as LocationsAdapter).notifyDataSetChanged()
            recycler_view.layoutManager= LinearLayoutManager(this)
            recycler_view.setHasFixedSize(true)


        }
    }

适配器（LocationsAdapter）：

import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Button
import android.widget.ImageButton
import android.widget.TextView
import android.widget.Toast
import androidx.recyclerview.widget.RecyclerView
import kotlinx.android.synthetic.main.saved_location_layout.view.*

class LocationsAdapter(private val locationList:List<LocationItem>):RecyclerView.Adapter<LocationsAdapter.LocationViewHolder>() {

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): LocationViewHolder {
        //passes the layout to the recycler
        val itemView = LayoutInflater.from(parent.context).inflate(R.layout.saved_location_layout, parent, false)

        return LocationViewHolder(itemView)
    }

    override fun onBindViewHolder(holder: LocationViewHolder, position: Int) {
        val currentItem = locationList[position]

        holder.imageButton.setImageResource(currentItem.image)

        holder.textView1.text = currentItem.text1
        holder.textView2.text = currentItem.text2
        holder.textView3.text = currentItem.text3


    }
    //sets the count to the number of locations in the list
    override fun getItemCount() = locationList.size

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

        val imageButton: ImageButton = itemView.btn_location
        val textView1: TextView = itemView.text_view_1
        val textView2: TextView = itemView.text_view_2
        val textView3: TextView = itemView.text_view_3
        val editButton:Button = itemView.btn_edit
    }
}

有两个按钮，btn_edit 和 btn_location，我需要每个按钮去另一个活动。非常感谢任何有关如何做到这一点的帮助。

Answer 1

您可以为您的适配器创建一个简单的 ClickListener，例如像这样

class LocationsAdapter(private val locationList:List<LocationItem>, private val listener: OnLocationButtonClickListener):RecyclerView.Adapter<LocationsAdapter.LocationViewHolder>() {

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): LocationViewHolder {
        //passes the layout to the recycler
        val itemView = LayoutInflater.from(parent.context).inflate(R.layout.saved_location_layout, parent, false)

        return LocationViewHolder(itemView)
    }

    override fun onBindViewHolder(holder: LocationViewHolder, position: Int) {
        val currentItem = locationList[position]
        holder.bind(currentItem)
    }
    //sets the count to the number of locations in the list
    override fun getItemCount() = locationList.size

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

        val imageButton: ImageButton = itemView.btn_location
        val textView1: TextView = itemView.text_view_1
        val textView2: TextView = itemView.text_view_2
        val textView3: TextView = itemView.text_view_3
        val editButton:Button = itemView.btn_edit

        fun bind(item: LocationItem) {

           imageButton.setImageResource(item.image)
           imageButton.setOnClickListener {
              listener.onImageClick(item)
           }
           textView1.text = item.text1
           textView2.text = item.text2
           textView3.text = item.text3
           editButton.setOnClickListener {
              listener.onEditClick(item)
           }
        }

    }


    interface OnLocationButtonClickListener {
       fun onEditClick(item: LocationItem)
       fun onImageClick(item: LocationItem)
    }

}

在您的活动中，您只需实现侦听器，覆盖方法并将其传递给您的适配器

class MainActivity : AppCompatActivity(), OnLocationButtonClickListener {

   ...


    fun populateRecycler(){
        val sharedPrefsDir = File(applicationInfo.dataDir, "shared_prefs")
        if(sharedPrefsDir.exists() && sharedPrefsDir.isDirectory()){
            //verifying that the directory is found and that it has the names
            val locateList = sharedPrefsDir.list();
            //This should be sending the number of recycler items to my createRecyclerContent function, to populate the recycler

            val locationsList = createRecyclerContent(locateList)

            recycler_view.adapter=LocationsAdapter(locationsList, this)
            (recycler_view.adapter as LocationsAdapter).notifyDataSetChanged()
            recycler_view.layoutManager= LinearLayoutManager(this)
            recycler_view.setHasFixedSize(true)


        }

        override fun onImageClick(item: LocationItem) {
           ...
        }

        override fun onEditClick(item: LocationItem) {
           ...
        }

    }

希望这会有所帮助！

Answer 2

在 YourActivity 类（您想从回收站视图项按钮单击中打开）和伴随对象内部使用

    companion object {

       fun start(context: Context) {
            val intent = Intent(context, "YourActivity"::class.java)
            context.startActivity(intent)
        } 
    }

在onBindViewHolder里面使用下面的代码调用

   override fun onBindViewHolder(holder: LocationViewHolder, position: Int) {
        val currentItem = locationList[position]

        holder.imageButton.setImageResource(currentItem.image)

        holder.textView1.text = currentItem.text1
        holder.textView2.text = currentItem.text2
        holder.textView3.text = currentItem.text3
       // you can use like this to visit your activity
        holder.editButton.setOnClickListener{
                     YourActivity.start(itemView.context)
             }
    }

Answer 3

我在这里找到了解决问题的方法：Access application context in companion object in kotlin

问题主要在于从传递给适配器的主要活动中获取正确的上下文。这是我现在正在运行的实现： MainAcitivity.kt：

open class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        LocationsAdapter.setContext(this)
        populateRecycler()


        //Pressing GPS icon will go to adding a new location
        fabAddLocation.setOnClickListener { view -> addLocation(view) }
    }

    fun addLocation(x: View?) {
        val locationIntent: Intent = Intent(this, AddLocation::class.java)
        startActivity(locationIntent)
        overridePendingTransition(R.anim.slide_in, R.anim.fade_out)

    }

    fun createRecyclerContent(list: Array<String>): ArrayList<LocationItem> {

        //Get the shared preference file data
        var size = list.size
        val itemList = ArrayList<LocationItem>()
        for (i in 0 until size) {
            val name = list[i].substring(0, list[i].length - 4)
            lateinit var prefs: SharedPreferences

            prefs = getSharedPreferences(name, Context.MODE_PRIVATE)

            val getTitle = prefs.getString("Title", "")
            val getDescription = prefs.getString("Description", "")
            val getGps = prefs.getString("Longitude", "") + "," + prefs.getString("Latitude", "")
            val listItem = LocationItem(
                R.drawable.ic_location_icon,
                getTitle.toString(),
                getDescription.toString(),
                getGps
            )

            itemList += listItem

        }
        return itemList

    }


    fun populateRecycler() {
        val sharedPrefsDir = File(applicationInfo.dataDir, "shared_prefs")
        if (sharedPrefsDir.exists() && sharedPrefsDir.isDirectory()) {
            //verifying that the directory is found and that it has the names
            val locateList = sharedPrefsDir.list();
            //This should be sending the number of recycler items to my createRecyclerContent function, to populate the recycler

            val locationsList = createRecyclerContent(locateList)

            recycler_view.adapter = LocationsAdapter(locationsList)
            (recycler_view.adapter as LocationsAdapter).notifyDataSetChanged()
            recycler_view.layoutManager = LinearLayoutManager(this)
            recycler_view.setHasFixedSize(true)


        }

    }
}
*

*LocationsAdapter 类文件：**

class LocationsAdapter(private val locationList:List<LocationItem>):RecyclerView.Adapter<LocationsAdapter.LocationViewHolder>() {

    companion object {
        private lateinit var context: Context

        fun setContext(con:Context){
            context=con
        }
    }
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): LocationViewHolder {

        //passes the layout to the recycler

        val itemView = LayoutInflater.from(parent.context).inflate(R.layout.saved_location_layout, parent, false)

        return LocationViewHolder(itemView)
    }

    override fun onBindViewHolder(holder: LocationViewHolder, position: Int) {



            fun EditALocation(context: Context) {
                val intent = Intent(context, EditLocation::class.java).apply {
                    putExtra("TITLE_DATA",holder.textView1.text.toString())
                }
                context.startActivity(intent)
            }

        val currentItem = locationList[position]


        holder.imageButton.setImageResource(currentItem.image)

        holder.textView1.text = currentItem.text1
        holder.textView2.text = currentItem.text2
        holder.textView3.text = currentItem.text3
        holder.editButton.setOnClickListener {
           EditALocation(context)
        }


    }

    //sets the count to the number of locations in the list
    override fun getItemCount() = locationList.size

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


        val imageButton: ImageButton = itemView.btn_location
        val textView1: TextView = itemView.text_view_1
        val textView2: TextView = itemView.text_view_2
        val textView3: TextView = itemView.text_view_3
        val editButton:Button = itemView.btn_edit

        }

    }