AppWidget 中的 ListView 不显示来自 firebase 的数据

如何解决AppWidget 中的 ListView 不显示来自 firebase 的数据

我有一个带有 ListView 的 AppWidget。当使用一个虚拟的arrayList exampleData 时，ListView 会显示它的数据。但是当我尝试从 firebase RD 检索数据到 todayList 时，我的 ListView 不显示数据。当我检查 todayList 的大小时，它不是 0，这意味着 todayList 成功检索到数据。你能帮我吗？

ListView 使用 todayList

ListView 使用虚拟 exampleData

这是我的 ExampleWidgetItemFactory 课：

internal class ExampleWidgetItemFactory(private val context: Context,intent: Intent) :
    RemoteViewsFactory {
    private lateinit var database: DatabaseReference
    private lateinit var preferences: Preferences
    private val mGoogleSignInClient: GoogleSignInClient? = null
    private lateinit var auth: FirebaseAuth
    private lateinit var user: FirebaseUser

    private lateinit var userId: String
    private lateinit var userName:String

    private var todayList: ArrayList<Task> = arraylistof()
    private val appWidgetId: Int
    private val exampleData = arraylistof(
        "one","two","three","four","five","six","seven","eight","nine","ten"
    )

    override fun onCreate() {
        //connect to data source
        //Initialize
        database = FirebaseDatabase.getInstance().reference
        auth = Firebase.auth

        //User
        user = auth.currentUser
        userId = user.uid.toString()

        //Calendar
        val calendar = Calendar.getInstance()
        val year = calendar.get(Calendar.YEAR)
        val month = calendar.get(Calendar.MONTH) + 1
        val day = calendar.get(Calendar.DAY_OF_MONTH)
        val date = String.format("%02d/%02d/%04d",day,month,year)

        database
                .child("users")
                .child(userId)
                .child("tasks")
                .addValueEventListener(object : ValueEventListener {
                    override fun onDataChange(snapshot: DataSnapshot) {
                        //Hapus data dalam arraylist agar tidak jadi penumpukan data
                        todayList.clear()

                        //Ambil semua child dalam goal dan masukan ke items
                        var items = snapshot.children
                        //Lakukan iterasi pada setiap item lalu buat class dan tambahkan ke list
                        items.forEach {
                            var task = it.getValue(Task::class.java)
                            todayList.add(task!!)
                        }
                        Log.v("gal",todayList.size.toString())
                        Log.v("gal",todayList[0].title.toString())
                        SystemClock.sleep(3000)
                    }

                    override fun onCancelled(error: DatabaseError) {
                        Todo("Not yet implemented")
                    }

                })
    }

    override fun onDataSetChanged() {

    }
    override fun onDestroy() {
        //close data source
    }

    override fun getCount(): Int {
        return exampleData.size
    }

    override fun getViewAt(position: Int): RemoteViews {
        val views = RemoteViews(context.packageName,R.layout.example_widget_item)
        views.setTextViewText(R.id.example_widget_item_text,todayList[position].title)
        val fillIntent = Intent()
        fillIntent.putExtra(ExampleWidgetProvider().EXTRA_ITEM_POSITION,position)
        views.setonClickFillInIntent(R.id.example_widget_item_text,fillIntent)
        SystemClock.sleep(500)
        return views
    }

    override fun getLoadingView(): RemoteViews? {
        return null
    }

    override fun getViewTypeCount(): Int {
        return 1
    }

    override fun getItemId(position: Int): Long {
        return position.toLong()
    }

    override fun hasstableIds(): Boolean {
        return true
    }

    init {
        appWidgetId = intent.getIntExtra(
            AppWidgetManager.EXTRA_APPWIDGET_ID,AppWidgetManager.INVALID_APPWIDGET_ID
        )
    }
}

**ExampleWidgetProvider **

class ExampleWidgetProvider : appwidgetprovider() {
    val ACTION_TOAST = "actionToast"
    val EXTRA_ITEM_POSITION = "extraItemPosition"

    override fun onUpdate(
        context: Context,appWidgetManager: AppWidgetManager,appWidgetIds: IntArray
    ) {
        super.onUpdate(context,appWidgetManager,appWidgetIds)
        for (appWidgetId in appWidgetIds) {
            val buttonIntent = Intent(context,HomeActivity::class.java)
            val buttonPendingIntent = PendingIntent.getActivity(
                context,buttonIntent,0
            )
            val prefs = context.getSharedPreferences(
                ExampleAppWidgetConfig().SHARED_PREFS,Context.MODE_PRIVATE
            )
            val buttonText = prefs.getString(
                ExampleAppWidgetConfig().KEY_BUTTON_TEXT + appWidgetId,"Press me"
            )
            val serviceIntent = Intent(context,ExampleWidgetService::class.java)
            serviceIntent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID,appWidgetId)
            serviceIntent.data = Uri.parse(serviceIntent.toUri(Intent.URI_INTENT_SCHEME))

            val clickIntent =
                Intent(
                    context,ExampleWidgetProvider::class.java
                )
            clickIntent.action = ACTION_TOAST

            val clickPendingIntent = PendingIntent.getbroadcast(
                context,clickIntent,0
            )

            val views = RemoteViews(context.packageName,R.layout.example_widget)
            views.setRemoteAdapter(R.id.example_widget_stack_view,serviceIntent)
            views.setEmptyView(R.id.example_widget_stack_view,R.id.example_widget_empty_view)
            views.setPendingIntentTemplate(R.id.example_widget_stack_view,clickPendingIntent)
            
            val appWidgetoptions = appWidgetManager.getAppWidgetoptions(appWidgetId)
            resizeWidget(appWidgetoptions,views)
            appWidgetManager.updateAppWidget(appWidgetId,views)
        }
    }

    override fun onAppWidgetoptionsChanged(
        context: Context,appWidgetId: Int,newOptions: Bundle
    ) {
        val views = RemoteViews(context.packageName,R.layout.example_widget)
        resizeWidget(newOptions,views)
        appWidgetManager.updateAppWidget(appWidgetId,views)
    }

    private fun resizeWidget(appWidgetoptions: Bundle,views: RemoteViews) {
        val minWidth = appWidgetoptions.getInt(AppWidgetManager.OPTION_APPWIDGET_MIN_WIDTH)
        val maxWidth = appWidgetoptions.getInt(AppWidgetManager.OPTION_APPWIDGET_MAX_WIDTH)
        val minHeight = appWidgetoptions.getInt(AppWidgetManager.OPTION_APPWIDGET_MIN_HEIGHT)
        val maxHeight = appWidgetoptions.getInt(AppWidgetManager.OPTION_APPWIDGET_MAX_HEIGHT)
    }

    override fun onDeleted(context: Context?,appWidgetIds: IntArray?) {
        Toast.makeText(context,"onDeleted",Toast.LENGTH_SHORT).show()
    }

    override fun onEnabled(context: Context?) {
        Toast.makeText(context,"onEnabled",Toast.LENGTH_SHORT).show()
    }

    override fun ondisabled(context: Context?) {
        Toast.makeText(context,"ondisabled",Toast.LENGTH_SHORT).show()
    }

    override fun onReceive(context: Context?,intent: Intent) {
        if (ACTION_TOAST == intent.action) {
            val clickedPosition = intent.getIntExtra(EXTRA_ITEM_POSITION,0)
            Toast.makeText(context,"Clicked position: $clickedPosition",Toast.LENGTH_SHORT).show()
        }
        super.onReceive(context,intent)
    }

}

**When I try getting size and element in `todayList`:**

    Log.v("gal",todayList.size.toString())
    Log.v("gal",todayList[0].title.toString())

**The logcat result:**

    2021-04-15 11:57:41.554 8756-8756/com.giftech.taskmastertest V/gal: 4
    2021-04-15 11:57:41.554 8756-8756/com.giftech.taskmastertest V/gal: vv

解决方法

为什么您认为您的项目应该显示在列表中？您正在从数据库中获取项目，在 todayList 中完成 forEach 和...仅此而已。你永远不会在任何地方返回这个 ArrayList，尤其是它没有设置到某个附加​​到 ListView 的适配器。看起来您已经剥离了很多代码，发布了整个课程 - 我敢打赌您的问题与异步数据库读取有关，onDataChange 的调用晚于绘图适配器/ListView，在此方法结束时，您应该可能调用 notifyDataSetChanged()

编辑：在发布整个类之后现在一切都清楚了：RemoteViewsFactory 正在根据传递给此类的数据生成视图，与适配器类似的工作。这不是从网络获取数据的时刻，因为这是异步操作，创建 RemoteViewsFactory 是一种同步方式，用于获取现有项目的视图。您应该在 extends AppWidgetProvider 类中（在 onUpdate() 方法中）获取数据，可能需要启动一些 Service 以进行异步数据获取并在存储整个数组刷新小部件 GUI 之后