使用MVVM在RecyclerView的网格和线性之间切换的更好方法是什么?

Question

我有一个RecyclerView和一个片段中的FAB。 FAB在网格和线性之间切换回收器视图的布局。

我在视图模型中有一个枚举类。

enum class LAYOUT { GRID, LINEAR }
private val _layout = MutableLiveData<LAYOUT>()
val layout: LiveData<LAYOUT>
get() = _layout

并且片段观察视图模型中布局值的可变实时数据。

我现在通过拥有 2 个 ListAdapter 来让它工作，一个用于网格，一个用于线性。 下面是我的片段代码。

val gridAdapter = MovieGridAdapter()
viewModel.layout.observe(viewLifecycleOwner, Observer {
if (it == GRID) {
binding.recyclerViewMovie.adapter = gridAdapter
binding.recyclerViewMovie.layoutManager = GridLayoutManager(context, 3)
} else {
binding.recyclerViewMovie.adapter = linearAdapter
binding.recyclerViewMovie.layoutManager = LinearLayoutManager(context)
}
})
viewModel.trendingMovies.observe(viewLifecycleOwner, Observer {
it?.let {
gridAdapter.submitList(it)
linearAdapter.submitList(it)
}
})

我觉得这不是最好的方法，因为我现在在片段中有 2 个适配器，我需要为两个适配器提交列表。

如果有更好的方法，请让我知道，谢谢！

Answer 1

您不需要使用两个适配器，一个适配器可以完成工作

class ProductListAdapter(
private val listener: OnProductListener) : PagedListAdapter<Product, ProductViewHolder>( PRODUCT_COMPARATOR ) {
var layoutId: Int = R.layout.list_item_product
override fun onBindViewHolder(holder: ProductViewHolder, position: Int) {
val product = getItem(position)
with(holder) {
bindTo(product,true)
product.let { product ->
itemView.setOnClickListener {
product.product_id?.let { it1 -> listener.onProductSelected(it1) }
}
}
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ProductViewHolder {
val view =
LayoutInflater.from(parent.context)
.inflate(layoutId, parent, false)
return ProductViewHolder(view)
}
override fun getItemViewType(position: Int): Int {
return position
}
fun setLayoutResourceId(layoutId: Int) {
this.layoutId = layoutId
}

companion object {
private val PRODUCT_COMPARATOR = object : DiffUtil.ItemCallback<Product>() {
override fun areItemsTheSame(oldItem: Product, newItem: Product): Boolean =
TextUtils.equals(
oldItem.product_id,
newItem.product_id
) 
override fun areContentsTheSame(
oldItem: Product,
newItem: Product
): Boolean =
oldItem == newItem
}
}
}

---

在片段中定义适配器

private var productsAdapter: ProductListAdapter = ProductListAdapter(this)
viewModel.trendingMovies.observe(viewLifecycleOwner, Observer {
it?.let {
productsAdapter.submitList(it)
}
})

---

显示列表

private fun showList() {
rv_products.layoutManager = LinearLayoutManager(activity, RecyclerView.VERTICAL, false)
productsAdapter.setLayoutResourceId(R.layout.list_item_list_product)
rv_products.adapter = productsAdapter
}

---

显示网格

private fun showGrid() {
rv_products.layoutManager = GridLayoutManager(activity, 3)
productsAdapter.setLayoutResourceId(R.layout.list_item_grid_product)
rv_products.adapter = productsAdapter
}