android - Kotlin 中的 RecyclerView itemClickListener

Question

在拥有 3 年的 Android 经验后，我正在使用 Kotlin 编写我的第一个应用程序。只是对如何在 Kotlin 中使用带有 RecyclerView 的 itemClickListener 感到困惑。

我已经尝试过 trait (edit: now interface) 方法，非常类似于 Java

public class MainActivity : ActionBarActivity() {

  protected override fun onCreate(savedInstanceState: Bundle?) {

    // set content view etc go above this line

    class itemClickListener : ItemClickListener {
      override fun onItemClick(view: View, position: Int) {
        Toast.makeText(this@MainActivity, "TEST: " + position, Toast.LENGTH_SHORT).show()
      }
    }

    val adapter = DrawerAdapter(itemClickListener())
    mRecyclerView.setAdapter(adapter)
 }

  trait ItemClickListener {
    fun onItemClick(view: View, position: Int)
  }
}

这似乎很多余，所以我尝试了内部类方法:

inner class ItemClickListener {
    fun onItemClick(view: View, position: Int) {
        startActivityFromFragmentForResult<SelectExerciseActivity>(SELECT_EXERCISES)
    }
}

然后像这样设置适配器的点击监听器:

val adapter = WorkoutsAdapter(ItemClickListener())

但我仍然对此不满意，因为我认为可能有更好、更清洁的方法。我试图从本质上实现这样的目标: RecyclerView onClick

有什么建议吗？

最终选择了批准答案的变体

在activity中定义函数:

val itemOnClick: (View, Int, Int) -> Unit = { view, position, type ->
    Log.d(TAG, "test")
}

像这样将函数本身传递给适配器:

class ExercisesAdapter(val itemClickListener: (View, Int, Int) -> Unit) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
      // other stuff up here
      val vhExercise = ExerciseVH(view) // view holder
      // on to the view holder through the extension function
      vhExercise.onClick(itemClickListener)
    }
}

在下面批准的答案中通过 Loop 扩展功能。

fun <T : RecyclerView.ViewHolder> T.onClick(event: (view: View, position: Int, type: Int) -> Unit): T {
    itemView.setOnClickListener {
        event.invoke(it, getAdapterPosition(), getItemViewType())
    }
    return this
}

Answer 1

我的解决方案就像以前的解决方案与来自 Activity 的 super 干净调用的组合。

ContactAdapter:

class ContactAdapter @Inject constructor() : RecyclerView.Adapter<ContactAdapter.ViewHolder>() {

    var onItemClick: ((Contact) -> Unit)? = null
    var contacts: List<Contact> = emptyList()

    ...

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        val contact = contacts[position]

        holder.email.text = contact.email
    }

    inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
        val email: TextView = itemView.email

        init {
            itemView.setOnClickListener {
                onItemClick?.invoke(contacts[adapterPosition])
            }
        }
    }
}

联系 Activity :

override fun setupRecyclerAdapter() {
    recyclerView.adapter = contactAdapter
    recyclerView.layoutManager = LinearLayoutManager(this)

    contactAdapter.onItemClick = { contact ->

        // do something with your item
        Log.d("TAG", contact.email)
    }
}