android - 在 pagedListAdaper 中添加边界回调

Question

我正在使用房间和实时数据在适配器中显示数据，但我想在 dB 中没有旧消息时从服务器下载数据。我想知道如何在实时数据或 pagedList 中添加 setBoundryCallback

Answer 1

您可能已经解决了它，但这里有一个可能的解决方案:

1. 为列表的元素定义一个 BoundaryCallback(在本例中我将其命名为 Object)

MyBoundaryCallback.kt

class MyBoundaryCallback(val context: Context): PagedList.BoundaryCallback<Object>(){

   // This is called when you reach the end of the list currently in the database.
   // You should make the call to the server here
   override fun onItemAtEndLoaded(itemAtEnd: Object) {
        Toast.makeText(context, "Reached the end of the list", Toast.LENGTH_SHORT).show()
   }

   // This is called when no data is in the database
   override fun onZeroItemsLoaded() {

      Toast.makeText(context, "0 items loaded", Toast.LENGTH_SHORT).show()
   }
}

1. 在您的存储库中，或在您定义分页列表的任何地方，将 setBoundary 添加到您的调用中

你的 repository.kt

// somewhere in the code
val factory: DataSource.Factory<Int, Object> = myDao.getObjects()

val pagedListBuilder: LivePagedListBuilder<Int, Object> = LivePagedListBuilder<Int, Object>(factory, 10)
              .setBoundaryCallback(JokeBoundaryCallback(context!!))
              .build()