Prosto: hapus boilerplate saat bekerja dengan RecyclerView

Untuk menampilkan daftar data yang kami gunakan RecyclerView(- Terima kasih, cap!). Dia tahu banyak hal dari kotak dan blablab terkenal lainnya. Tapi ada banyak rasa sakit dengannya. Tidak ada yang suka menulis kode boilerplate yang sama. Dan aku tidak benar-benar ...

Sejarah singkat plot "Kurangi kode sedikit"

Misalnya, Orang kelas data sederhana () dibuat: dengan nama depan, nama belakang, email. ketersediaan surat dan anjing.

Untuk menampilkan daftar orang, Anda harus membuat RecyclerView.Adapterdan RecyclerView.ViewHolder, sebagian besar kode + yang sama.

Adapter ViewHolder-, . , , ViewHolder, .

Adapter ViewHolder, .

RecyclerView.Adapter<RecyclerView.ViewHolder>

class ClassicAdapter : RecyclerView.Adapter<ClassicHolder>() {

    private val viewModel = PersonItemViewModel()

    private val data: List<Person>
        get() = viewModel.data

    fun setData(persons: List<Person>) {
        viewModel.data = persons
        notifyDataSetChanged()
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ClassicHolder =
        ClassicHolder.create(parent)

    override fun getItemCount(): Int = data.size

    override fun onBindViewHolder(holder: ClassicHolder, position: Int) {
        holder.bind(viewModel, position)
    }
}

class ClassicHolder(private val binding: ItemPersonBinding) : RecyclerView.ViewHolder(binding.root) {
    fun bind(viewModel: PersonItemViewModel, position: Int) {
        binding.setVariable(BR.viewModel, viewModel)
        binding.setVariable(BR.position, position)
        binding.executePendingBindings()
    }

    companion object {
        fun create(parent: ViewGroup): ClassicHolder {
            val inflater = LayoutInflater.from(parent.context)
            val binding: ItemPersonBinding =
                DataBindingUtil.inflate(inflater, R.layout.item_person, parent, false)
            return ClassicHolder(binding)
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<layout>
    <data>
        <variable
            name="position"
            type="Integer" />

        <variable
            name="viewModel"
            type="plus.yeti.prostoadapter.ui.main.PersonItemViewModel" />
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout>

        <TextView
            android:text="@{viewModel.getName(position)}"
            ... />

        <TextView
            android:text="@{viewModel.getEmail(position)}"
            .../>

        <ImageView
            app:visible="@{viewModel.hasDog(position)}" 
            .../>

    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

class PersonItemViewModel : ProstoViewModel<Person>() {
    override var data: List<Person> = emptyList()

    fun getName(position: Int) = data[position].lastName + ", " + data[position].firstName
    fun getEmail(position: Int) = data[position].email
    fun hasDog(position: Int): Boolean = data[position].hasDog
}

ProstoAdapter ProstoHolder

, Adapter ViewHolder , .

ProstoViewModel. , ProstoViewModel, , , . ViewModel -:

abstract class ProstoViewModel<T>: ViewModel() {
    abstract var data: List<T>
}

ProstoHolder

open class ProstoHolder<TBinding : ViewDataBinding>(val binding: TBinding) : RecyclerView.ViewHolder(binding.root) {
    open fun <TData, TViewModel : ProstoViewModel<TData>> bind(viewModel: TViewModel, position: Int) {
        binding.setVariable(BR.viewModel, viewModel)
        binding.setVariable(BR.position, position)
        binding.executePendingBindings()
    }

    companion object {
        fun <TBinding : ViewDataBinding> create(parent: ViewGroup, layoutId: Int): ProstoHolder<TBinding> {
            val inflater = LayoutInflater.from(parent.context)
            val binding: TBinding = DataBindingUtil.inflate(inflater, layoutId, parent, false)
            return ProstoHolder(binding)
        }
    }
}

, , ProstoAdapter:

abstract class ProstoAdapter<TBinding : ViewDataBinding, TData> : RecyclerView.Adapter<ProstoHolder<TBinding>>() {

    abstract val viewModel: ProstoViewModel<TData>
    abstract val layoutId: Int

    private var dataSize: Int = 0

    open fun setData(data: List<TData>) {
        this.dataSize = data.size
        viewModel.data = data
        notifyDataSetChanged()
    }

    open var onBind: ((ProstoHolder<TBinding>) -> Unit)? = null

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ProstoHolder<TBinding> =
        ProstoHolder.create(parent, layoutId)

    override fun getItemCount(): Int = dataSize

    override fun onBindViewHolder(holder: ProstoHolder<TBinding>, position: Int) {
        holder.bind(viewModel, position)
        onBind?.invoke(holder)
    }
}

Adapter-a ViewModel c , item's layout id Binding-, layout-, item-.

, :)

class MainFragment : Fragment() {
    private val adapter =
        object : ProstoAdapter<ItemPersonBinding, Person>() {
            override val viewModel = PersonItemViewModel()
            override val layoutId = R.layout.item_person
        }

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        mainRecyclerView.adapter = adapter
    }

    fun setNewPersonList(persons: List<Person>){
        adapter.setData(personList)
    }
}

4 .

github.com/klukwist/Prosto

ViewHolder-.

:)