kotlin 中的 SectionedRecyclerViewAdapter

Question

Anyone can refactor java code to kotlin code ?

this is my code

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)
    }
}

I got a problem is "Expression 'adapter' of type 'RecyclerView.Adapter<(raw) RecyclerView.ViewHolder!>?' cannot be invoked as a function. The function 'invoke()' is not found" after recyclerView.adapter(sectionAdapter) Someone please guide me to fix this. sorry i not good at english

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)
}

And for your activity you don't need context variable 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
    }
}

as @CampbellMG mentioned you need to either use recyclerView.adapter = sectionAdapter or recyclerView.setAdapter(sectionAdapter)

recyclerView.adapter=sectionAdapter is more idiomatic

Answer 2

You are trying to access a class property as a function

In Java you would set the adapter with:

recyclerView.setAdapter(sectionAdapter)

In Kotlin this looks like:

recyclerView.adapter = sectionAdapter

Have a look here for more information.