Kotlin 在片段中显示类型不匹配

Question

我有一个片段，里面有 RecyclerAdapter。我想在 onCreateView 方法中初始化适配器，但它在这个语句

中抛出 "Type mismatch. Required : Context , Found : FragmentActivity" 的错误

我不知道为什么第一个显示这个错误而第二个不包含编译时错误。

显示错误

recyclerView!!.adapter = RestaurantMenuAdapter(activity)

没有显示错误

recyclerView!!.layoutManager = LinearLayoutManager(activity)

Fragment.kt

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
                          savedInstanceState: Bundle?): View? {
    // Inflate the layout for this fragment
    val view = inflater.inflate(R.layout.fragment_restaurant_menu, container, false)
    recyclerView = view.findViewById(R.id.restaurant_container)
    recyclerView!!.adapter = RestaurantMenuAdapter(activity)
    recyclerView!!.layoutManager = LinearLayoutManager(activity)

RecyclerAdapter.kt

class RestaurantMenuAdapter  (val context : Context) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
        val inflater = parent.context.getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater
        return object : RecyclerView.ViewHolder(inflater.inflate(R.layout.item_menu1, parent, false)) {

        }
    }

    override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {

    }

    override fun getItemCount(): Int {
        return 10
    }
}

Answer 1

将此更改为-：

recyclerView!!.adapter = RestaurantMenuAdapter(activity)

收件人-:

recyclerView!!.adapter = RestaurantMenuAdapter(activity.applicationContext)

Answer 2

回收器适配器的变化从上下文到 Activity.

class RestaurantMenuAdapter  (val context : Activity) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
        val inflater = parent.context.getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater
        return object : RecyclerView.ViewHolder(inflater.inflate(R.layout.item_menu1, parent, false)) {

        }
    }

    override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {

    }

    override fun getItemCount(): Int {
        return 10
    }
}

Answer 3

保持适配器原样，只在初始化适配器的地方使用"activity!!"。

recyclerView.adapter = RestaurantMenuAdapter(activity!!)

您的适配器将保持不变。

class RestaurantMenuAdapter  (val context : Context) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
    val inflater = parent.context.getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater
    return object : RecyclerView.ViewHolder(inflater.inflate(R.layout.item_menu1, parent, false)) {

    }
}

override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {

}

override fun getItemCount(): Int {
    return 10
}
}

Answer 4

recyclerView!!.adapter = RestaurantMenuAdapter(this)

到

recyclerView!!.adapter = RestaurantMenuAdapter(this.requireActivity())

Kotlin 在片段中显示类型不匹配

Kotlin showed type mismatch in fragment

android

android-context

android-fragments

kotlin