Question

我正在实施RecyclerView，并想获得所选项目的详细信息。我正在按照给定here的教程进行操作。但是我想获取一些字符串键而不是项目位置。

例如，如果我这样做：

for (selection in selectionTracker?.selection!!)
    Log.e("tag", selection.toString())

我将索引作为输出，但是我想在这里获取字符串键。

但是我不知道如果我这样做，应该做哪些进一步的改变：

fun getItemDetails() = object: ItemDetailsLookup.ItemDetails<Long>() {
    override fun getSelectionKey() = itemId
    override fun getPosition() = adapterPosition
}

并将其更改为：

fun getItemDetails() = object: ItemDetailsLookup.ItemDetails<Long>() {
    override fun getSelectionKey() = myData[adapterPosition].myKey // a string
    override fun getPosition() = adapterPosition
}

----编辑---- 这些是我的代码：

适配器类：

class AdapterSubjectsIndexRV (
    private val indexList: ArrayList<ModelSubjectsIndex>,
    val itemClick: (String) -> Unit
): RecyclerView.Adapter<AdapterSubjectsIndexRV.MyViewHolder>() {

    // every recycler view item has unique id
    init {
        setHasStableIds(true)
    }

    // Provide a reference to the views for each data item
    // Complex data items may need more than one view per item, and
    // you provide access to all the views for a data item in a view holder.
    inner class MyViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
        val courseValue = itemView.findViewById<TextView>(R.id.course_value)!!
        val courseCode = itemView.findViewById<TextView>(R.id.course_code)!!
        val courseName = itemView.findViewById<TextView>(R.id.course_name)!!
        val progressValue = itemView.findViewById<TextView>(R.id.progress_value)!!
        val progressBar = itemView.findViewById<ProgressBar>(R.id.progress_bar)!!
        val selectedOverlay = itemView.findViewById<View>(R.id.subjects_card_view_selected)!!

        // set click events
        init {
            itemView.setOnClickListener {
                itemClick(courseCode.text.toString())
            }
        }

        // get item details
        fun getItemDetails() = object: ItemDetailsLookup.ItemDetails<String>() {
            // override fun getSelectionKey() = itemId
            override fun getSelectionKey() = indexList[adapterPosition].courseCode
            override fun getPosition() = adapterPosition
        }

    }

    // lookup class
    class MyItemDetailsLookup(private val rv: RecyclerView): ItemDetailsLookup<String>() {
        override fun getItemDetails(e: MotionEvent): ItemDetails<String>? {
            val v = rv.findChildViewUnder(e.x, e.y)
            return if (v != null) {
                (rv.getChildViewHolder(v) as MyViewHolder).getItemDetails()
            } else null
        }
    }

    // set tracker
    var tracker: SelectionTracker<Long>? = null

    // Create new views (invoked by the layout manager)
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): AdapterSubjectsIndexRV.MyViewHolder {
        // create a new view
        val itemView = LayoutInflater.from(parent.context).inflate(R.layout.subjects_card, parent, false)
        return MyViewHolder(itemView)
    }

    // Replace the contents of a view (invoked by the layout manager)
    override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
        holder.courseValue.text = indexList[position].courseValue
        holder.courseCode.text = indexList[position].courseCode
        holder.courseName.text = indexList[position].courseName
        holder.progressValue.text = "${indexList[position].progress}%"
        holder.progressBar.progress = indexList[position].progress

        // Highlight the item if it's selected
        holder.selectedOverlay.visibility = if (tracker!!.isSelected(position.toLong())) View.VISIBLE else View.INVISIBLE
    }

    // Return the size of your data set (invoked by the layout manager)
    override fun getItemCount() = indexList.size

    override fun getItemId(position: Int): Long {
        return position.toLong()
    }
}

这就是我设置片段的方式：

val rvAdapter = AdapterSubjectsIndexRV(getSubjectsIndexList(subjectsList)) {
    // if not in selection mode
    if (selectionTracker?.selection?.size() == 0) {
        listener.showSubjectDetails(it)
    }
}

// set recycler view
val recyclerView = theView.findViewById<RecyclerView>(R.id.subjects_recycler_view)
recyclerView.apply {
    setHasFixedSize(true)
    layoutManager = LinearLayoutManager(activity)

    adapter = rvAdapter
}

// set selection tracker
selectionTracker = SelectionTracker
     .Builder<Long>(
        "subjects_index_selection",
        recyclerView,
        StableIdKeyProvider(recyclerView),
       AdapterSubjectsIndexRV.MyItemDetailsLookup(recyclerView),
        StorageStrategy.createLongStorage()
   ).withSelectionPredicate(
        SelectionPredicates.createSelectAnything()
   ).build()

rvAdapter.tracker = selectionTracker

if(savedInstanceState != null)
       selectionTracker?.onRestoreInstanceState(savedInstanceState)

return theView

Answer 1

将通用类型从testDB更改为<Long>，然后您将可以返回字符串键。

<String>

Answer 2

我对您的代码有些困惑，但是获取详细信息的最佳方法是在onBindViewHolder方法上进行操作。调用on click方法，然后在其中执行您的方法以获取字符串。

如何在Android的recyclerview-selection中设置String键？

2 个答案: