无法在 kotlin 的 firebase 实时数据库中读取嵌套子节点

Question

我想读取 location 中的值并将其存储在数组中。但是当我运行代码时，我在数组中得到空值。在这里，我试图读取 -MgvP468FQ-jclZWHC5S 节点中的值。如何读取值并将其存储在数组中。我在 lat1、long1.

中没有得到任何值

var ref1= FirebaseDatabase.getInstance().getReference("location").child("oBwEgUfhMbQoPPovRXkgWJcHz6B2")

ref1.addValueEventListener(object : ValueEventListener{
    override fun onDataChange(p0: DataSnapshot) {
        if (p0.exists()){
            for (idsnapshot in p0.children){
                for (locsnapshot in idsnapshot.child("-MgvP468FQ-jclZWHC5S").children){

                    val lat1 = locsnapshot.child("latitude").value as Double
                    val long1 = locsnapshot.child("longitude").value as Double

                    Log.d("TAG", "$locsnapshot")

                    Toast.makeText(requireContext() ,"success$locsnapshot", Toast.LENGTH_SHORT).show()


                    Toast.makeText(requireContext() ,"success$lat1,$long1", Toast.LENGTH_SHORT).show()


                    lat = lat1.toDouble()
                    val LatLng = LatLng(lat1, long1)
                    list.add(LatLng)


                }
            }
        }

    }

    override fun onCancelled(p0: DatabaseError) {

    }

})

Answer 1

据我所知，您在处理数据时存在一些错误。

这应该更接近：

ref1.addValueEventListener(object : ValueEventListener{
  override fun onDataChange(snapshot: DataSnapshot) {
    if (snapshot.exists()){
      for (childsnapshot in snapshot.child("-MgvP468FQ-jclZWHC5S").children){  //  children location8 and location9
        for (locsnapshot in childsnapshot.children){ //  children 0..4
          val lat1 = locsnapshot.child("latitude").value as Double
          val long1 = locsnapshot.child("longitude").value as Double
          ...
        }
      }
    }

无法在 kotlin 的 firebase 实时数据库中读取嵌套子节点

Failure to read nested child node in firebase realtime database in kotlin

arrays

kotlin

firebase-realtime-database

children