Question

当我单击项目时，没有任何反应我尝试更改颜色，以显示所选元素的数量，以显示日志什么都没发生

MyViewHolder

class MyViewHolder(view: View) : RecyclerView.ViewHolder(view) {

val name: TextView = view.list_item_name
val phone: TextView = view.list_item_phone

// More code here
fun getItemDetails(): ItemDetailsLookup.ItemDetails<Long> =
    object : ItemDetailsLookup.ItemDetails<Long>() {
        override fun getSelectionKey(): Long? = itemId

        override fun getPosition(): Int = adapterPosition

    }

}

我的ItemDetailsLookup

class MuLookup(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 MyViewHolder)
                .getItemDetails()
        }
        return null
    }
}

我的适配器

class PersonAdapter(
    private val listItems: List<Person>,
    private val context: Context
) : RecyclerView.Adapter<MyViewHolder>() {

    init {
        setHasStableIds(true)
    }

    private var tracker: SelectionTracker<Long>? = null

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
        return MyViewHolder(
            LayoutInflater.from(context)
                .inflate(R.layout.list_item_jf, parent, false)
        )
    }

    override fun getItemCount(): Int {
        return listItems.size
    }

    override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
        holder.name.text = listItems[position].name
        holder.phone.text = listItems[position].phone

        val parent = holder.name.parent as LinearLayout

        if (tracker!!.isSelected(position.toLong())) {
            parent.background = ColorDrawable(
                Color.parseColor("#80deea")
            )
        } else {
            Timber.i("zeze ${tracker!!.selection}")
            // Reset color to white if not selected
            parent.background = ColorDrawable(Color.WHITE)
        }

    }

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

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

}

我的活动

class MainActivity : AppCompatActivity() {

    private var tracker: SelectionTracker<Long>? = null

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

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

        val myList = listOf(
            Person("Alice", "555-0111"),
            Person("Bob", "555-0119"),
            Person("Carol", "555-0141"),
            Person("Dan", "555-0155"),
            Person("Eric", "555-0180"),
            Person("Craig", "555-0145")
        )

        my_rv.layoutManager = LinearLayoutManager(this)
        my_rv.setHasFixedSize(true)

        val adapter = PersonAdapter(myList, this)
        my_rv.adapter = adapter

        tracker = SelectionTracker.Builder<Long>(
            "selection-1",
            my_rv,
            StableIdKeyProvider(my_rv),
            MuLookup(my_rv),
            StorageStrategy.createLongStorage()
        ).withSelectionPredicate(
            SelectionPredicates.createSelectAnything()
        ).build()

        tracker?.addObserver(
            object : SelectionTracker.SelectionObserver<Long>() {
                override fun onSelectionChanged() {
                    val nItems: Int? = tracker?.selection?.size()

                    if (nItems != null && nItems > 0) {

                        // Change title and color of action bar

                        title = "$nItems items selected"
                        supportActionBar?.setBackgroundDrawable(
                            ColorDrawable(Color.parseColor("#ef6c00"))
                        )
                    } else {

                        // Reset color and title to default values

                        title = "RVSelection"
                        supportActionBar?.setBackgroundDrawable(
                            ColorDrawable(Color.parseColor("#126c00"))
                        )
                    }
                }
            })

        adapter.setTracker(tracker)


    }

    override fun onSaveInstanceState(outState: Bundle) {
        super.onSaveInstanceState(outState)

        tracker?.onSaveInstanceState(outState)
    }
}

谢谢

解决方案：Tracker的工作原理是像Khaled Qasem建议一样在视图上添加了setOnClickListener

override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
    holder.name.text = listItems[position].name
    holder.phone.text = listItems[position].phone

    val parent = holder.name.parent as LinearLayout

    holder.name.setOnClickListener {
        Timber.i("zeze ici")
        if (tracker!!.isSelected(position.toLong())) {
            Timber.i("zeze la")
            parent.background = ColorDrawable(
                Color.parseColor("#80deea")
            )
        } else {
            Timber.i("zeze ${tracker!!.selection}")
            // Reset color to white if not selected
            parent.background = ColorDrawable(Color.WHITE)
        }
    }
}

颜色变化和项目数显示在supportActionBar

Answer 1

代替此操作，您只需要在创建视图持有者时添加一个Click Listener：

override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {

    val myViewHolder = MyViewHolder(
        LayoutInflater.from(context)
            .inflate(R.layout.list_item_jf, parent, false)
    )
    myViewHolder.setOnClickListener {
        // Add what you what you need here
    }
    return myViewHolder
}

Answer 2

在我的情况下，解决方案是告诉用户长按第一个选择：

长按可进行第一个设置，然后点击其他设置进行多次选择

我的实现方式有所不同，但是我还观察到SelectionTracker从我的RecyclerView中什么也没选择。我从某些SelectionTracker example code中无法理解它应该如何工作。该示例显示了ViewHolder回收后如何设置高光：

override fun onBindViewHolder(holder: ViewHolder, position: Int) {
    val number = list[position]
    tracker?.let {
        holder.bind(number, it.isSelected(position.toLong()))
    }
}

fun bind(value: Int, isActivated: Boolean = false) {
    text.text = value.toString()
    itemView.isActivated = isActivated
}

但是当用户点击该行时，isActivated应该如何设置为true？

答案是用户不应该点击；用户应该长按：

要开始选择项目，我们必须先长按任意一个项目以激活多重选择模式。

Answer 3

问题在于，只有当最初选择一项时，才激活Recyclerview选择，然后您只需轻按即可选择其他项。

如果您始终需要用户选择一个项目或选择一个项目，则可以使用selectionTracker最初从recyclerview中选择一个项目：

selectionTracker.select(someItemId)

现在，您只需单击列表即可从列表中选择其他项目。

SelectionTracker在我的Recyclerview中未选择任何内容

3 个答案: