在 kotlin android 项目中更新另一个类的视图的最佳设计模式是什么？

Question

我有一个用电容器构建的混合应用程序，但是我需要实现一些本机代码以使用 android 演示类来使用辅助显示器。我需要根据从电容器接收到的数据更新我的演示视图，实现此目的的最佳设计模式是什么？

这是我的适配器

class CartItemAdapter(context: Context, private val cartItems: List<CartItem>) : ArrayAdapter<CartItem>(context, 0, cartItems) {
  override fun getView(position: Int, convertView: View?, parent: ViewGroup): View {
    val view = convertView ?: LayoutInflater.from(context).inflate(R.layout.customer_list_item, parent, false)

    val item = getItem(position) ?: return view // Safely unwrapping

    // Bind the view elements to your data
    view.findViewById<TextView>(R.id.itemDescription).text = item.description

    return view
  }
}

这是我的电容器插件方法，它被调用并从电容器接收数据：

  @PluginMethod
  fun transactionChange(call: PluginCall){
    val itemsJson = call.getString("items")
    println(itemsJson)

    val transaction = itemsJson?.let { Json.decodeFromString<Transaction>(it) }
    transaction?.let {

    }
    val ret = JSObject()
    ret.put("items", transaction)
    call.resolve(ret)
  }
  suspend fun login(): User {
    val credentials = Credentials.anonymous()
    return app.login(credentials)
  }
}```

What is the best way to update my view in the seperate class?


I have tried calling a companion method, however that requires a context and I understand that passing that context in is an anti pattern, I'm just trying to find the correct design pattern for this.

Answer 1

这不是一个很好的答案，因为我从未使用过Presentation，也没有测试过它。但我认为就像使用 Activity 或 Fragment 一样，您设置内容视图，然后获取对其中所需视图的引用并对它们执行操作。

不幸的是，

lifecycleScope

（在 UI 层中运行协程的典型方法）将不可用，因为它不是 Activity 或 Fragment。因此，您需要为此创建一个 CoroutineScope，并在演示文稿被销毁时将其取消，以避免泄漏。

所以我认为你的代码看起来大概是这样的：

class MyPresentation(
    display: Display,
    context: Context
) : Presentation(context, display) {

    private val scope = MainScope()
    init {
        setOnDismissListener { scope.cancel() }
    }

    // ...

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

        val recyclerView = findViewById(R.id.recycler_view)
        val adapter = CartItemAdapter(context, emptyList())
        recyclerView.adapter = adapter

        // I don't know anything about Capacitor but let's assume you have some
        // sort of reference to it here.

        scope.launch {
            val loginResult = capacitorPlugin.login()
            // do something with login result, maybe update some views?
            val dataList = capacitorPlugin.getSomeData()
            adapter.cartItems = dataList // you'll have to make cartItems a public var
            adapter.notifyDataSetChanged()
        }
    }

}