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Android Studio – How to refresh list item after sorting immediately

I have a music list obtained from:

MusicDatabase.kt

override fun getContentProviderValue(): MutableList<Songs> {

    val songList =  mutableListOf<Songs>()
    val collection = sdk29AndUp {
        MediaStore.Audio.Media.getContentUri(MediaStore.VOLUME_EXTERNAL)
    } ?:  MediaStore.Audio.Media.EXTERNAL_CONTENT_URI

    //Get songs from provider
    context.contentResolver.query(
        collection,
        projection,
        selection,
        null,
        PreferenceHelper.storeAllSongsSortOrder //Sort order.
    ).use { cursor -> 
    ............
 }
}

Using SharedPreference, I am storing and obtaining sort order like this:

PreferenceHelper.kt

//store allSongs sort order
var storeAllSongsSortOrder: String?
    get() = preferences.getString(allSongSortOrder.first, allSongSortOrder.second)
    set(value) = preferences.edit {
        if (value != null) {
          it.putString(allSongSortOrder.first, value)
    }
}

I obtain the songList like this:

SongsFragment.kt

 mainViewModel.mediaItems.observe(viewLifecycleOwner){ result->
 when(result.status) {
 Status.SUCCESS -> {
 result.data?.let { songs ->        
 allSongsAdapter.songs = songs
 ........
 }

In my songs fragment, when user clicks "Sort", a dropdown will appear with 2 options:

  1. Sort by name
  2. Sort by date

When user clicks sort by name, I do this:

SongsFragment.kt

PreferenceHelper.storeAllSongsSortOrder = Constants.SORT_TITLE
binding.rcvAllSongs.invalidate()
allSongsAdapter.notifyDataSetChanged()

When user clicks sort by date, I do this:

 PreferenceHelper.storeAllSongsSortOrder = Constants.SORT_LAST_ADDED
 binding.rcvAllSongs.invalidate()
 allSongsAdapter.notifyDataSetChanged()

PROBLEM: The list is not updating real time as I select, I have to close the app and open before my list gets the selected sort order.

I want – when I click e.g "Sort by date" – The list should update immediately and display songs based on date added.

Tags:

2

Answers


  1. 0

    You are not assigning the updated list to allSongsAdapter after user presses a button.

     PreferenceHelper.storeAllSongsSortOrder = Constants.SORT_LAST_ADDED | Constants.SORT_TITLE
 binding.rcvAllSongs.invalidate()
 allSongsAdapter.songs = songs         // You have to update the Adapter data set with sorted list
 allSongsAdapter.notifyDataSetChanged()

    So either you make sure that mainViewModel.mediaItems.observe is invoked when user selects sort, which is only possible if MusicTable is updated or you save the list received in mainViewModel.mediaItems.observe in a variable and then sort and reassign it when user wants to sort the list

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  2. 0

    You can propably do something like this:

    class YourFragment : Fragment {
 
  private val allSongsAdapter = SongsAdapter()

  override fun onCreateView(
    inflater: LayoutInflater,
    container: ViewGroup?,
    savedInstanceState: Bundle?
  ): View {
    //init your views, bindins, view model and your recycler view adapter
    //...
    binding.recyclerView.adapter = allSongsAdapter
  }
  
  //...
  override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    mainViewModel.songList.observe(viewLifecycleOwner, { result ->
      when (result.status) {
        Status.SUCCESS -> {
          allSongsAdapter.updateList(result.data)
        }
      }
    })
    
    //or whatever you have on your UI to change your filter
    binding.sortFilter.setOnClickListener { filter ->
      mainViewModel.updateSortFilter(filter)
    }
    
    //....
    viewModel.initList()
  }
}

    class YourViewModel() : ViewModel() {

  private var _unsortedSongList: List<String> = emptyList()
  
  private val _songList = MutableLiveData<Songs>()
  val songList: LiveData<Songs> = _songList

  private lateinit var musicDatabase: MusicDatabase

  init {
    musicDatabase = //get the dependency or inject it from constructor
    _unsortedSongList = musicDatabase.getContentProviderValue()
  }

  fun initList() {
    _songList.value = sortSongs(PreferencesHelper.storeAllSongsSortOrder)
  }

  fun updateSortFilter(sortFilter: String) {
    PreferencesHelper.storeAllSongsSortOrder = sortFilter
    _songList.value = sortSongs(sortFilter)
  }

  private fun sortSongs(sortFilter: String): List<Songs> {
    var sortedList: List<Songs> = emptyList()
    switch (sortFilter) {
      Constants.SORT_LAST_ADDED -> {
        sortedList = _unsortedSongList.sortedBy { it.createdMillis }
      }
      Constants.SORT_LAST_ADDED -> {
        sortedList = _unsortedSongList.sortedBy { it.name }
      }
    }
    return sortedList
  }


}

    class SongsAdapter : RecyclerView.Adapter<SongItemAdapter.ViewHolder> {
  private val songsList = mutableListOf<Songs>()

  fun updateList(list: List<Songs>) {
    songsList.clear()
    songsList.addAll(list)
    notifyDataSetChanged()
  }

  //.... the rest of your adapter and viewholder
}
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