Android-在我从Firebase Storage获取所有下载链接后，无法更新RecyclerView

Question

我想从Firebase Storage获取所有视频文件，并将其显示在RecyclerView中。我已经设法获取了所有文件，但一旦检索到所有文件，我就无法更新RecyclerView。这是代码

recyclerViewVideoList.setHasFixedSize(true)
recyclerViewVideoList.layoutManager = LinearLayoutManager(this)
recyclerViewVideoList.adapter = VideoListRecyclerViewAdapter(applicationContext,videoList, this)
getVideos()
private fun getVideos() {
val listRef = firebaseStorage.reference.child("videos")
listRef.listAll()
.addOnSuccessListener { listResult ->
listResult.items.forEach { item ->
item.downloadUrl.addOnSuccessListener {
videoList.add(Video(item.name, it.toString(), "565656"))
}
}
recyclerViewVideoList.adapter!!.notifyDataSetChanged()
}
.addOnFailureListener {
Toast.makeText(applicationContext, "Something went wrong. Please try again", Toast.LENGTH_SHORT).show()
}
}

这里有一个解决方案，但它多次调用notifyDataSetChanged((。我想避免那样做。

Answer 1

更有效的解决方案是仅对列表项的最后一个元素调用notifyDataSetChanged((函数。通过这样做，只对最后一个元素执行notifyDataSetChanged((函数，并更新所有回收器视图。

更改此项：

.addOnSuccessListener { listResult ->
listResult.items.forEach { item ->
item.downloadUrl.addOnSuccessListener {
videoList.add(Video(item.name, it.toString(), "565656"))
}
}
recyclerViewVideoList.adapter!!.notifyDataSetChanged()
}

这个

//Declare one integer count variable var count = 0
.addOnSuccessListener { listResult ->
listResult.items.forEach { item ->
item.downloadUrl.addOnSuccessListener {
videoList.add(Video(item.name, it.toString(), "565656"))
count++
if(count == listResult.items.size)
recyclerViewVideoList.adapter!!.notifyDataSetChanged()  
}
}
}

Answer 2

更改此项：

.addOnSuccessListener { listResult ->
listResult.items.forEach { item ->
item.downloadUrl.addOnSuccessListener {
videoList.add(Video(item.name, it.toString(), "565656"))
}
}
recyclerViewVideoList.adapter!!.notifyDataSetChanged()
}

进入这个：

.addOnSuccessListener { listResult ->
listResult.items.forEach { item ->
item.downloadUrl.addOnSuccessListener {
videoList.add(Video(item.name, it.toString(), "565656"))
recyclerViewVideoList.adapter!!.notifyDataSetChanged()
}
}