android - 如何在 androidx.recyclerview.widget 中使用 androidx.recyclerview.selection。或者如何在 android 中使用 kotlin 在 recyclerview 中选择一个项目？

Question

我创建了一个水平回收器 View ，其中加载了项目。之后，我需要选择该项目并执行点击事件。到这个存档(代码在下面可用)，现在我想改变点击项目的颜色，剩下的项目应该被取消选择。如果我没有正确查询，请道歉。

这一切都是使用 Kotlin 的 Androidx Recyclerview 构建的。这是 sample code !我正在寻找一个解决方案来扩展它以选择项目并更改其颜色。

使用 kotlin 编码的 Android Activity

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.view.WindowManager
import androidx.recyclerview.widget.LinearLayoutManager
import kotlinx.android.synthetic.main.activity_sample.*
import androidx.recyclerview.widget.RecyclerView



class SampleActivity : AppCompatActivity() {

    val bottle_name: ArrayList<String> = ArrayList()
    val bottle_img: ArrayList<Int> = ArrayList()
    val bottle_type: ArrayList<String> = ArrayList()

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

        addBottles()


        val adptr = BottlesAdaptor(bottle_name, bottle_img, bottle_type);
        bottles_list.adapter = adptr

        val layoutManager = LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false)
        val recyclerView = bottles_list
        recyclerView.setLayoutManager(layoutManager)

    }

    override fun onWindowFocusChanged(hasFocus: Boolean) {
        super.onWindowFocusChanged(hasFocus)
        if (hasFocus) {
            hideSystemUI()
        }
    }

    private fun hideSystemUI() {
        val decorView = window.decorView
        decorView.systemUiVisibility = (
                View.SYSTEM_UI_FLAG_IMMERSIVE
                        or View.SYSTEM_UI_FLAG_LAYOUT_STABLE
                        or View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
                        or View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
                        or View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
                        or View.SYSTEM_UI_FLAG_FULLSCREEN
                )
        window.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

    }

    fun addBottles(){
        bottle_name.add("Coca1");
        bottle_name.add("Coca2");
        bottle_name.add("Coca3");
        bottle_name.add("Coca4");
        bottle_name.add("Coca5");
        bottle_name.add("Coca6");
        bottle_name.add("Coca7");
        bottle_name.add("Coca8");
        bottle_type.add("cooldrink");
        bottle_type.add("cooldrink");
        bottle_type.add("cooldrink");
        bottle_type.add("cooldrink");
        bottle_type.add("cooldrink");
        bottle_type.add("wine");
        bottle_type.add("wine");
        bottle_type.add("wine");
        bottle_img.add(R.drawable.coca1);
        bottle_img.add(R.drawable.coca2);
        bottle_img.add(R.drawable.coca3);
        bottle_img.add(R.drawable.coca4);
        bottle_img.add(R.drawable.coca5);
        bottle_img.add(R.drawable.coca6);
        bottle_img.add(R.drawable.coca7);
        bottle_img.add(R.drawable.coca8);


    }

使用 Kotlin 编码的 Bottles 适配器

import android.content.Context
import android.util.Log
import android.view.LayoutInflater
import android.view.ViewGroup
import android.view.View
import android.widget.ArrayAdapter
import android.widget.ImageView
import android.widget.TextView
import androidx.recyclerview.widget.LinearLayoutManager
import kotlinx.android.synthetic.main.bottle_list_item.view.*
import androidx.recyclerview.widget.RecyclerView


class BottlesAdaptor(private val dataSet: ArrayList<String>, private val dataSet2: ArrayList<Int>, private val dataSet3: ArrayList<String>) :
    RecyclerView.Adapter<BottlesAdaptor.ViewHolder>() {

    /**
     * Provide a reference to the type of views that you are using (custom ViewHolder)
     */
    class ViewHolder(v: View) : RecyclerView.ViewHolder(v) {
        val textView: TextView
        val imageView: ImageView
        val textView2:TextView

        init {
            // Define click listener for the ViewHolder's View.
            v.setOnClickListener {
                Log.d(TAG, "Element $adapterPosition clicked.")
// I have tried this but it is not giving me the opportunity to select a color for the selected item 
                if (v.id==adapterPosition){
                    v.setBackgroundResource(R.drawable.bottle_card_selected);
                }
                else{
                    v.setBackgroundResource(R.drawable.bottle_card);
                }
            }
            textView = v.findViewById(R.id.bottle_list_text)
            imageView = v.findViewById(R.id.bottle_list_img)
            textView2 = v.findViewById(R.id.bottle_list_subtext)
        }
    }

    // Create new views (invoked by the layout manager)
    override fun onCreateViewHolder(viewGroup: ViewGroup, viewType: Int): ViewHolder {
        // Create a new view.
        val v = LayoutInflater.from(viewGroup.context)
            .inflate(R.layout.bottle_list_item, viewGroup, false)

        return ViewHolder(v)
    }

    // Replace the contents of a view (invoked by the layout manager)
    override fun onBindViewHolder(viewHolder: ViewHolder, position: Int) {
        Log.d(TAG, "Element $position set.")

        // Get element from your dataset at this position and replace the contents of the view
        // with that element
        viewHolder.textView.text = dataSet[position]
        viewHolder.textView2.text = dataSet3[position]
        viewHolder.imageView.setImageResource(dataSet2[position])
    }

    // Return the size of your dataset (invoked by the layout manager)
    override fun getItemCount() = dataSet.size


    companion object {
        private val TAG = "CustomAdapter"
    }
}

我期待一种更好的解决方案。如果可能的话，还希望禁用特定按钮。它应该给recyclerview的可选项目的选项

Answer 1

首先，将以下内容添加到您的 build.gradle(应用级):

implementation "androidx.recyclerview:recyclerview-selection:1.0.0

在 RecyclerView Adapter BottlesAdaptor 中设置选择跟踪器:

private var tracker: SelectionTracker<Long>? = null

    fun setTracker(tracker: SelectionTracker<Long>?) {
        this.tracker = tracker
    }

在您的 Activity SampleActivity 中使用以下方法来实现选择跟踪器:

private fun trackSelectedItems() {
        tracker = SelectionTracker.Builder<Long>(
                "selection-1",
                bottles_list,
                ItemIdKeyProvider(bottles_list),
                ItemLookup(bottles_list),
                StorageStrategy.createLongStorage()
        ).withSelectionPredicate(SelectionPredicates.createSelectAnything())
                .build()

        adptr?.setTracker(tracker)

        tracker?.addObserver(object: SelectionTracker.SelectionObserver<Long>() {
            override fun onSelectionChanged() {
                //handle the selected according to your logic
            }
        })
}

像这样添加 ItemIdKeyProvider():

inner class ItemIdKeyProvider(private val recyclerView: RecyclerView)
        : ItemKeyProvider<Long>(SCOPE_MAPPED) {

        override fun getKey(position: Int): Long? {
            return recyclerView.adapter?.getItemId(position)
                    ?: throw IllegalStateException("RecyclerView adapter is not set!")
        }

        override fun getPosition(key: Long): Int {
            val viewHolder = recyclerView.findViewHolderForItemId(key)
            return viewHolder?.layoutPosition ?: RecyclerView.NO_POSITION
        }
}

添加 ItemLookup，如下所示:

inner class ItemLookup(private val rv: RecyclerView)
        : ItemDetailsLookup<Long>() {
        override fun getItemDetails(event: MotionEvent)
                : ItemDetails<Long>? {

            val view = rv.findChildViewUnder(event.x, event.y)
            if(view != null) {
                return (rv.getChildViewHolder(view) as BottlesAdaptor.ViewHolder)
                        .getItemDetails()
            }
            return null
        }
}

由于您还提到 现在我想更改被点击项目的颜色并且应该取消选择剩余项目，因此在您的 Adapter 的onBindViewHolder()` 中添加以下代码:

tracker?.let {
    if (it.isSelected(position.toLong()) )  {
        it.select(position.toLong())
        //changing the  color of the clicked/selected item to light gray
        //parent.setBackgroundColor( ContextCompat.getColor(context, R.color.extra_light_gray))
    } else {
        it.deselect(position.toLong())
        // set color white
        //parent.setBackgroundColor( ContextCompat.getColor(context, R.color.white))
    }
}