why progress bar loading not showing actual data in fragment android?

Question

I am developing music app but when I run project only progressbar loading in my fragment not showing actual data I want to know exactly where I am making mistake

below my HomeFragment.kt

@AndroidEntryPoint
class HomeFragment : Fragment() {

    lateinit var mainViewModel: MainViewModel
    private var _binding: FragmentHomeBinding? = null
    private val binding get() = _binding!!

    @Inject
    lateinit var songAdapter: SongAdapter

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View {

        // inflate the layout and bind to the _binding
        _binding = FragmentHomeBinding.inflate(inflater, container, false)

        return binding.root
    }


    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        mainViewModel = ViewModelProvider(requireActivity())[MainViewModel::class.java]
        setupRecyclerView()
        subscribeToObservers()

        songAdapter.setOnItemClickListener {
            mainViewModel.playOrToggleSong(it)
        }
    }

    private fun setupRecyclerView() = binding.rvAllSongs.apply {
        adapter = songAdapter
        layoutManager = LinearLayoutManager(requireContext())
    }

    private fun subscribeToObservers() {
        mainViewModel.mediaItems.observe(viewLifecycleOwner) { result ->
            when(result.status) {
                Status.SUCCESS -> {
                    binding.allSongsProgressBar.isVisible = false
                    result.data?.let { songs ->
                        songAdapter.songs = songs
                    }
                }
                Status.ERROR -> Unit
                Status.LOADING -> binding.allSongsProgressBar.isVisible = true
            }
        }

    }

}

below my fragment_home.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ui.MainActivity">

    <ProgressBar
        android:id="@+id/allSongsProgressBar"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:visibility="gone"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rvAllSongs"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

below list_item.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <ImageView
        android:id="@+id/ivItemImage"
        android:layout_width="75dp"
        android:layout_height="75dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <com.google.android.material.textview.MaterialTextView
        android:id="@+id/tvPrimary"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginLeft="16dp"
        android:layout_marginRight="16dp"
        android:gravity="center|left"
        android:text="Playlist Title"
        android:layout_marginTop="8dp"
        android:textSize="20sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/ivItemImage"
        app:layout_constraintTop_toTopOf="parent" />

    <com.google.android.material.textview.MaterialTextView
        android:id="@+id/tvSecondary"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:text="100 Songs"
        android:textSize="14sp"
        android:layout_marginLeft="16dp"
        android:layout_marginRight="16dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/ivItemImage"
        app:layout_constraintTop_toBottomOf="@+id/tvPrimary" />

</androidx.constraintlayout.widget.ConstraintLayout>

below my Songadapter class

class SongAdapter @Inject constructor(
    private val glide: RequestManager
) : RecyclerView.Adapter<SongAdapter.SongViewHolder>() {

    //private lateinit var binding:ListItemBinding

    inner class SongViewHolder(val binding: ListItemBinding) : RecyclerView.ViewHolder(binding.root)

    private val diffCallback = object : DiffUtil.ItemCallback<Song>() {
        override fun areItemsTheSame(oldItem: Song, newItem: Song): Boolean {
            return oldItem.mediaId == newItem.mediaId
        }

        override fun areContentsTheSame(oldItem: Song, newItem: Song): Boolean {
            return oldItem.hashCode() == newItem.hashCode()
        }
    }

    private val differ = AsyncListDiffer(this, diffCallback)

    var songs: List<Song>
    get() = differ.currentList
    set(value) = differ.submitList(value)

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): SongViewHolder {
       val binding =  ListItemBinding.inflate(LayoutInflater.from(parent.context), parent, false)

        return SongViewHolder(binding)

    }

    override fun onBindViewHolder(holder: SongViewHolder, position: Int) {
        val song = songs[position]
        holder.binding.apply {
            tvPrimary.text = song.title
            tvSecondary.text = song.subtitle
            glide.load(song.imageUrl).into(ivItemImage)

            holder.binding.root.setOnClickListener {
                onItemClickListener?.let { click ->
                    click(song)
                }
            }
        }
    }

    private var onItemClickListener: ((Song) -> Unit)? = null

    fun setOnItemClickListener(listener: (Song) -> Unit) {
        onItemClickListener = listener
    }

    override fun getItemCount(): Int {
        return songs.size
    }
}

below my MainViewModel.kt class

@HiltViewModel
class MainViewModel @Inject constructor(
    private val musicServiceConnection: MusicServiceConnection
) : ViewModel() {
    
        private val _mediaItems = MutableLiveData<Resource<List<Song>>>()
        val mediaItems: LiveData<Resource<List<Song>>> = _mediaItems
        val isConnected = musicServiceConnection.isConnected
        val networkError = musicServiceConnection.networkError
        val curPlayingSong = musicServiceConnection.curPlayingSong
        val playbackState = musicServiceConnection.playbackState
    
        init {
            _mediaItems.postValue(Resource.loading(null))
            musicServiceConnection.subscribe(
                MEDIA_ROOT_ID,
                object : MediaBrowserCompat.SubscriptionCallback() {
                    override fun onChildrenLoaded(
                        parentId: String,
                        children: MutableList<MediaBrowserCompat.MediaItem>
                    ) {
                        super.onChildrenLoaded(parentId, children)
                        val items = children.map {
                            Song(
                                it.mediaId!!,
                                it.description.title.toString(),
                                it.description.subtitle.toString(),
                                it.description.mediaUri.toString(),
                                it.description.iconUri.toString()
    
    
                            )
                        }
                        _mediaItems.postValue(Resource.success(items))
                    }
                })
    
    
        }
    
        fun skipToNextSong() {
            musicServiceConnection.transportControls.skipToNext()
        }
    
        fun skipToPreviousSong() {
            musicServiceConnection.transportControls.skipToPrevious()
        }
    
        fun seekTo(pos: Long) {
            musicServiceConnection.transportControls.seekTo(pos)
        }
    
        fun playOrToggleSong(mediaItem: Song, toggle: Boolean = false) {
            val isPrepared = playbackState.value?.isPrepared ?: false
            if (isPrepared && mediaItem.mediaId == curPlayingSong.value?.getString(METADATA_KEY_MEDIA_ID)) {
                playbackState.value?.let { playbackState ->
                    when {
                        playbackState.isPlaying -> if (toggle) musicServiceConnection.transportControls.pause()
                        playbackState.isPlayEnabled -> musicServiceConnection.transportControls.play()
                        else -> Unit
                    }
    
                }
            } else {
                musicServiceConnection.transportControls.playFromMediaId(mediaItem.mediaId, null)
            }
        }
    
        override fun onCleared() {
            super.onCleared()
            musicServiceConnection.unsubscribe(
                MEDIA_ROOT_ID,
                object : MediaBrowserCompat.SubscriptionCallback() {})
        }

}

Below MusicServiceConnection.kt

class MusicServiceConnection(
    context: Context
) {

    private val _isConnected = MutableLiveData<Event<Resource<Boolean>>>()
    val isConnected: LiveData<Event<Resource<Boolean>>> = _isConnected
    private val _networkError = MutableLiveData<Event<Resource<Boolean>>>()
    val networkError: LiveData<Event<Resource<Boolean>>> = _networkError
    private val _playbackState = MutableLiveData<PlaybackStateCompat?>()
    val playbackState: LiveData<PlaybackStateCompat?> = _playbackState
    private val _curPlayingSong = MutableLiveData<MediaMetadataCompat?>()
    val curPlayingSong: LiveData<MediaMetadataCompat?> = _curPlayingSong
    lateinit var mediaController: MediaControllerCompat

    private val mediaBrowserConnectionCallback = MediaBrowserConnectionCallback(context)
    private val mediaBrowser = MediaBrowserCompat(
        context,
        ComponentName(
            context,
            MusicService::class.java
        ),
        mediaBrowserConnectionCallback,
        null

    ).apply {
        connect()
    }
    val transportControls: MediaControllerCompat.TransportControls
        get() = mediaController.transportControls


    fun subscribe(parentId:String, callback: MediaBrowserCompat.SubscriptionCallback){
        mediaBrowser.subscribe(parentId, callback)
    }

    fun unsubscribe(parentId:String, callback: MediaBrowserCompat.SubscriptionCallback){
        mediaBrowser.unsubscribe(parentId, callback)
    }

    private inner class MediaBrowserConnectionCallback(
        private val context: Context
    ) : MediaBrowserCompat.ConnectionCallback() {
        override fun onConnected() {
            mediaController = MediaControllerCompat(context, mediaBrowser.sessionToken).apply {
                registerCallback(MediaControllerCallback())
            }
            _isConnected.postValue(Event(Resource.success(true)))
        }

        override fun onConnectionSuspended() {
            _isConnected.postValue(
                Event(
                    Resource.error(
                        "The connection was suspended",
                        false
                    )
                )
            )
        }

        override fun onConnectionFailed() {
            _isConnected.postValue(
                Event(
                    Resource.error(
                        "Could connect media browser",
                        false
                    )
                )
            )
        }
    }

    private inner class MediaControllerCallback : MediaControllerCompat.Callback() {
        override fun onPlaybackStateChanged(state: PlaybackStateCompat?) {
            _playbackState.postValue(state)
        }


        override fun onMetadataChanged(metadata: MediaMetadataCompat?) {
            _curPlayingSong.postValue(metadata)
        }

        override fun onSessionEvent(event: String?, extras: Bundle?) {
            super.onSessionEvent(event, extras)
            when (event) {

                NETWORK_ERROR -> _networkError.postValue(
                    Event(
                        Resource.error(
                            "Could not connect to the server. Please check your internet connection",
                            null
                        )
                    )
                )

            }
        }

        override fun onSessionDestroyed() {
            mediaBrowserConnectionCallback.onConnectionSuspended()
        }
    }

}

what I have tried I have done debugging it is not coming till on status== success and onerror it skipping success and onerror in debug mode it is only showing what is happening in onloading

I want to know where exactly I am making mistake and why data not showing

Answer 1

problem was in my musicservice in onloadchildren previously it was written like this

override fun onLoadChildren(
        parentId: String,
        result: Result<MutableList<MediaBrowserCompat.MediaItem>>
    ) {
        when (parentId) {
            MEDIA_ROOT_ID -> {
                val resultsSent = firebaseMusicSource.whenReady { isInitialized ->
                    if (isPlayerInitialized) {
                        result.sendResult(firebaseMusicSource.asMediaItems())
                        if (!isInitialized && firebaseMusicSource.songs.isNotEmpty()) {
                            preparePlayer(
                                firebaseMusicSource.songs,
                                firebaseMusicSource.songs[0],
                                false
                            )
                            isPlayerInitialized = true
                        }
                    } else {
                        mediaSession.sendSessionEvent(NETWORK_ERROR, null)
                        result.sendResult(null)

                    }

                }
                if (!resultsSent) {
                    result.detach()
                }
            }
        }
    }
}

bt I changed inside if block like this if (isInitialized) then it solved my problem