kotlin 中的 SectionedRecyclerViewAdapter

Question

任何人都可以將 java 代碼重構為 kotlin 代碼？

這是我的代碼

FoodListAdapter.kt

class FoodListAdapter: StatelessSection(SectionParameters.builder()
    .itemResourceId(R.layout.content_food_list)
    .headerResourceId(R.layout.header_food_list)
    .build()) {

    val itemList = arrayListOf<Int>(1, 2, 3 ,4)

    override fun getContentItemsTotal(): Int {
        return itemList.size
    }

    override fun onBindItemViewHolder(holder: RecyclerView.ViewHolder?, position: Int) {
        val itemHolder = holder as MyItemViewHolder

        // bind your view here
        itemHolder.tvItem.setText(itemList[position])
    }

    override fun getItemViewHolder(view: View?): RecyclerView.ViewHolder {
        return MyItemViewHolder(view!!)
    }
}

class MyItemViewHolder(itemView: View): RecyclerView.ViewHolder(itemView) {
    lateinit var tvItem: TextView
    init {
        tvItem = itemView.findViewById(R.id.txtItem) as TextView
    }
}

FoodListActivity.kt

class FoodActivity : AppCompatActivity() {

private var context: Context? = null

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

    context = this
    val sectionAdapter = SectionedRecyclerViewAdapter()

// Add your Sections
        sectionAdapter.addSection(FoodListAdapter())

// Set up your RecyclerView with the SectionedRecyclerViewAdapter
        val recyclerView = findViewById(R.id.foodList) as RecyclerView
        recyclerView.setLayoutManager(LinearLayoutManager(context))
        recyclerView.adapter(sectionAdapter)
    }
}

我遇到的問題是“'RecyclerView.Adapter<(raw) RecyclerView.ViewHolder!> 類型的表達式'適配器'？” 不能作為函數調用。在 recyclerView.adapter(sectionAdapter) 之后找不到函數“invoke()”“有人請指導我解決這個問題。 抱歉我英語不好

Answer 1

class FoodListAdapter(val itemList): StatelessSection(SectionParameters.builder()
    .itemResourceId(R.layout.content_food_list)
    .headerResourceId(R.layout.header_food_list)
    .build()) {

    override fun getContentItemsTotal(): Int {
        return itemList.size
    }

    override fun onBindItemViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
        val itemHolder = holder as MyItemViewHolder
        itemHolder.tvItem.setText(itemList[position])
    }

    override fun getItemViewHolder(view: View?): RecyclerView.ViewHolder {
        return MyItemViewHolder(view!!)
    }
}

class MyItemViewHolder(itemView: View): RecyclerView.ViewHolder(itemView) {
    internal val tvItem: TextView =itemView.findViewById(R.id.txtItem)
}

對於您的活動，您不需要上下文變量 Activity extends Context

class FoodActivity : AppCompatActivity() {

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

    val sectionAdapter = SectionedRecyclerViewAdapter()

        val itemList = arrayListOf<Int>(1, 2, 3 ,4)
        sectionAdapter.addSection(FoodListAdapter(itemList))

        val recyclerView:RecyclerView = findViewById(R.id.foodList)
        recyclerView.layoutManager = LinearLayoutManager(context)
        recyclerView.adapter = sectionAdapter
    }
}

正如@CampbellMG 提到的，您需要使用recyclerView.adapter = sectionAdapter或recyclerView.setAdapter(sectionAdapter)

recyclerView.adapter=sectionAdapter更慣用

Answer 2

您正在嘗試將類屬性作為函數訪問

在 Java 中，您可以使用以下內容設置適配器：

recyclerView.setAdapter(sectionAdapter)

在 Kotlin 中，這看起來像：

recyclerView.adapter = sectionAdapter

在這里查看更多信息。