Android Studio Java Recycler View problem.

int[] first_playlist_order = {1,2,5};

public class MainActivity extends AppCompatActivity {
    private Spinner spinner;
    public MediaPlayer mp;
    public ArrayList<Song> songs;
    private MusicAdapter mainAdapter;
    private RecyclerView rvPlayList;
    private Button playOrPauseButton, nextButton, previousButton, editButton;
    public SongArchive songArchive;
    private String[] active_playlist;
    private int selectedSong, selectedPlayList;
    private int[] playlist_song_order;
    private String[] playListNames;
    public List<String> playListList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        playListList = new ArrayList<String>();
        spinner = findViewById(R.id.playListSpinner);
        songArchive = new SongArchive();
        songArchive.setSongTitles();
        playListList.add("Playlist 1");
        playListList.add("Playlist 2");
        selectedSong = 0;
        int[] first_playlist_order = {1,2,5};
        updatePlayList(first_playlist_order);
        addListener();
        mpPlayer(selectedSong);
        spinner();
        setUpRecyclerView();
        addRecyclerViewListener();
    }

    private void updatePlayList(int[] setPlayListOrder){
        playlist_song_order = new int[setPlayListOrder.length];
        for(int i = 0; i < setPlayListOrder.length; i++){
            playlist_song_order[i] = setPlayListOrder[i];
        }
        active_playlist = songArchive.getPlayList(playlist_song_order);
    }

    private void addNewPlayList(){
        playListList.add("Create new playlist");
    }

    private void setUpRecyclerView(){
        int size = playlist_song_order.length;
        rvPlayList = findViewById(R.id.mainPlayListRecyclerView);
        songs = Song.createPlayList(0);
        for(int i = 0; i < size; i++){
            songs.add(new Song(songArchive.getPrettySongTitles(playlist_song_order[i]), songArchive.getPrettySongLength(playlist_song_order[i])));
        }
        mainAdapter = new MusicAdapter(songs);
        mainAdapter.setSmallOrLarge("large");
        rvPlayList.setAdapter(mainAdapter);
        rvPlayList.setLayoutManager(new LinearLayoutManager(this));
    }

    private void playOrPause(String buttonTag){
        if(buttonTag.equals("play")){
            System.out.println("Song playing: "+ active_playlist.length);

            playOrPauseButton.setTag("pause");
            playOrPauseButton.setText(getString(R.string.pauseStr));
            mp.start();
        }if(buttonTag.equals("pause")){
            playOrPauseButton.setTag("play");
            playOrPauseButton.setText(getString(R.string.playStr));
            mp.pause();
        }
    }

    private void mpPlayer(int selected){
        try{
            if(mp.isPlaying()) {
                mp.pause();
            }
        }catch(NullPointerException error){
            System.out.println("NullPointerException");
        }
        mp = MediaPlayer.create(getApplicationContext(), getResources().getIdentifier(active_playlist[selected], "raw",getPackageName()));
        selectedSong = selected;
    }

    private void nextOrPrevious(String buttonTag){
        try{
            if(mp.isPlaying()) {
                mp.pause();
            }
        }catch(NullPointerException error){
            System.out.println("NullPointerException");
        }
        if(buttonTag.equals("next")){
            if(selectedSong < songArchive.getNumberOfSongsInPlayList()){
                selectedSong++;
                mpPlayer(selectedSong);
            }
        }if(buttonTag.equals("previous")){
            if(selectedSong > 0){
                selectedSong--;
                mpPlayer(selectedSong);
            }
        }
    }

    public void addListener() {
        playOrPauseButton = findViewById(R.id.playOrPauseButton);
        editButton = findViewById(R.id.editButton);
        nextButton = findViewById(R.id.nextButton);
        previousButton = findViewById(R.id.previousButton);
        playOrPauseButton.setOnClickListener(new InterfaceListener());
        nextButton.setOnClickListener(new InterfaceListener());
        previousButton.setOnClickListener(new InterfaceListener());
        editButton.setOnClickListener(new InterfaceListener());
    }

    private void addRecyclerViewListener(){
        Context context = null;
        rvPlayList.addOnItemTouchListener(
                new RecyclerViewItemClickListener(null, rvPlayList, new RecyclerViewItemClickListener.OnItemClickListener() {
                    @Override
                    public void onItemClick(View view, int position) {
                    System.out.println("Fast click");
                    mpPlayer(position);
                    }
                    @Override
                    public void onLongItemClick(View view, int position) {
                        view.setBackgroundColor(Color.GRAY);
                        System.out.println("Long click");
                    }
                })
        );
    }

    private class InterfaceListener implements View.OnClickListener{
        public void onClick(View caller){
            String buttonTag = caller.getTag().toString();
            if(buttonTag.equals("edit")){
                openEditPlayList();
            }
            nextOrPrevious(buttonTag);
            playOrPause(buttonTag);
        }
    }

    public void spinner(){
    playListNames = new String[playListList.size()];
        playListList.toArray(playListNames);
        ArrayAdapter<String> arrayAdapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_item, playListNames);
        arrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(arrayAdapter);
        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                selectedPlayList = position;
                setUpRecyclerView();
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {
            }
        });
    }

    public void openEditPlayList(){
        String plTitle = "Playlist "+String.valueOf(playListNames.length);
        Intent intent = new Intent(this, com.example.mediaplayertesting.EditPlayList.class);
        intent.putExtra(EditPlayList.PARAM_PLAY_LIST_TITLE, plTitle);
        intent.putExtra(EditPlayList.PARAM_PLAYLIST, playlist_song_order);
        startActivityForResult(intent, 0);
    }

    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        String returnTitle = data.getStringExtra(EditPlayList.RETURN_VALUE);
        int[] returnPLayListOrder = data.getIntArrayExtra(EditPlayList.RETURN_PLAY_LIST);
        for(int i = 0; i < returnPLayListOrder.length; i++){
            System.out.println("Return play list order "+i+" "+returnPLayListOrder[i]);
        }
        updatePlayList(returnPLayListOrder);
        spinner();
        System.out.println("Return test: "+ returnTitle);
    }
}

public class SongArchive {

    private final String Bensound_Epic = "bensoundepic";
    private final String Bensound_Sunny = "bensoundsunny";
    private final String Bensound_Energy = "bensoundenergy";
    private final String Calm_Piano = "calmpiano";
    private final String Cinematic_Chill_Hop = "cinematicchillhop";
    private final String Epic_Travel = "epictravel";
    private String[] songTitles;
    private String[] prettySongTitles;
    private String[] prettySongLength;
    private int numberOfSongsInArchive, numberOfSongsInPlayList;


    public void setSongTitles(){
        songTitles = new String[]{Bensound_Energy, Bensound_Epic, Bensound_Sunny, Calm_Piano, Cinematic_Chill_Hop, Epic_Travel};
        prettySongTitles = new String[]{"Bensound Energy","Bensound Epic","Bensound Sunny","Calm Piano","Cinematic Chill Hop","Epic Travel"};
        prettySongLength = new String[] {"2:59","2:58","2:20","1:26","3:03","1:00"};
        numberOfSongsInArchive = songTitles.length;
    }

    public String getPrettySongTitles(int get){
        return prettySongTitles[get];
    }

    public int getNrOfSongs(){
        return songTitles.length;
    }

    public String getPrettySongLength(int get){
        return prettySongLength[get];
    }

    public String[] getPlayList(int[] songs){
        List<String> localList = new ArrayList<String>();
        int j = 0;
        for(int i = 0; i < numberOfSongsInArchive; i++){
            if(songs[j] == i){
                localList.add(songTitles[i]);
                j++;
            }
        }
        setNumberOfSongsInPlayList(j);
        String[] localArray = new String[localList.size()];
        localList.toArray(localArray);
        return localArray;
    }

    public void setNumberOfSongsInPlayList(int number){
        numberOfSongsInPlayList = number;
    }

    public int getNumberOfSongsInPlayList(){
        if(numberOfSongsInPlayList == 0){
            return 0;
        }else
            return numberOfSongsInPlayList-1;
    }
}

public class Song {
    private String songName;
    private String songDuration;

    public Song(String song_name, String song_duration){
        songName = song_name;
        songDuration = song_duration;
    }

    public String getSongName() {
        return songName;
    }

    public String getSongDuration() {
        return songDuration;
    }

    public static ArrayList<Song> createPlayList(int numSongs){
        ArrayList<Song> songs = new ArrayList<>();
        for(int i = 0; i <= numSongs; i++){
        }
        return songs;
    }

}

public class EditPlayList extends AppCompatActivity {
    MusicAdapter adapter1, adapter2;
    ArrayList<Song> songs;
    public SongArchive songArchive;
    public Button addButton, removeButton, backButton;
    public EditText titleEditView;
    private RecyclerView playListRecyclerView, allSongRecyclerView;
    public static final String PARAM_PLAY_LIST_TITLE = "title";
    public static final String RETURN_VALUE = "return";
    public static final String PARAM_PLAYLIST = "PlayList";
    public static final String RETURN_PLAY_LIST = "return playlist";
    private int[] playList;
    public ArrayList<Integer> playListList;
    public String playListTitle;
    private int size, songSelected;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.edit_playlist);
        songArchive = new SongArchive();
        songArchive.setSongTitles();
        playListTitle = this.getIntent().getStringExtra(PARAM_PLAY_LIST_TITLE);
        playList = this.getIntent().getIntArrayExtra(PARAM_PLAYLIST);
        titleEditView = findViewById(R.id.titleTextView);
        titleEditView.setText(playListTitle);
        playListList = new ArrayList<Integer>();
        for(int i = 0; i < playList.length; i++){
            playListList.add(playList[i]);
        }
        System.out.println("Size list: "+ playListList.size());
        for(int i = 0; i < playList.length; i++){
            System.out.println(playListList.get(i));
        }
        size = playList.length;
        setUpRecyclerViewPlayListSongs();
        addRecyclerViewListenerPlayList();
        setUpRecyclerViewAllSongs();
        addRecyclerViewListenerAll();
        addListener();
    }

    private void setUpRecyclerViewPlayListSongs(){
        playListRecyclerView = findViewById(R.id.playListRecyclerView);
        songs = Song.createPlayList(0);
        for(int i = 0; i < size; i++){
            songs.add(new Song(songArchive.getPrettySongTitles(playList[i]), songArchive.getPrettySongLength(playList[i])));
        }
        adapter1 = new MusicAdapter(songs);
        adapter1.setSmallOrLarge("small");
        playListRecyclerView.setAdapter(adapter1);
        playListRecyclerView.setLayoutManager(new LinearLayoutManager(this));
    }

    private void setUpRecyclerViewAllSongs(){
        int nrOf = songArchive.getNrOfSongs();
        allSongRecyclerView = findViewById(R.id.allSongRecyclerView);
        songs = Song.createPlayList(0);
        for(int i = 0; i < nrOf; i++){
            songs.add(new Song(songArchive.getPrettySongTitles(i), songArchive.getPrettySongLength(i)));
        }
        adapter2 = new MusicAdapter(songs);
        adapter2.setSmallOrLarge("small");
        allSongRecyclerView.setAdapter(adapter2);
        allSongRecyclerView.setLayoutManager(new LinearLayoutManager(this));
    }

    public void setSongSelected(int intSong){
        songSelected = intSong;
    }

    public void addToPlayList(){
        playListList.add(songSelected);
        setUpRecyclerViewPlayListSongs();
    }

    public void removeFromPlayList(int remove){
        playListList.remove(remove);
    }

    private void addRecyclerViewListenerAll(){
        Context context = null;
        allSongRecyclerView.addOnItemTouchListener(
                new RecyclerViewItemClickListener(null, allSongRecyclerView, new RecyclerViewItemClickListener.OnItemClickListener() {
                    @Override
                    public void onItemClick(View view, int position) {
                        view.setBackgroundColor(Color.WHITE);
                        System.out.println("Fast click");
                    }
                    @Override
                    public void onLongItemClick(View view, int position) {
                        view.setBackgroundColor(Color.GRAY);
                        setSongSelected(position);
                    }
                })
        );
    }

    private void addRecyclerViewListenerPlayList(){
        Context context = null;
        playListRecyclerView.addOnItemTouchListener(
                new RecyclerViewItemClickListener(null, playListRecyclerView, new RecyclerViewItemClickListener.OnItemClickListener() {
                    @Override
                    public void onItemClick(View view, int position) {
                        view.setBackgroundColor(Color.WHITE);
                        System.out.println("Fast click");
                    }
                    @Override
                    public void onLongItemClick(View view, int position) {
                        view.setBackgroundColor(Color.GRAY);
                        setSongSelected(position);
                    }
                })
        );
    }

    public void addListener() {
        addButton = findViewById(R.id.addSongButton);
        removeButton = findViewById(R.id.removeSongButton);
        backButton = findViewById(R.id.backButton);
        addButton.setOnClickListener(new InterfaceListener());
        removeButton.setOnClickListener(new InterfaceListener());
        backButton.setOnClickListener(new InterfaceListener()); }

    private class InterfaceListener implements View.OnClickListener{
        public void onClick(View caller){
            String buttonTag = caller.getTag().toString();
            if(buttonTag.equals("back")){
                goBack();
            }
            if(buttonTag.equals("add")){
                addToPlayList();
            }
            if(buttonTag.equals("remove")){
                removeFromPlayList(songSelected);
            }
        }
    }


    public void goBack(){
        int[] temp = new int[playListList.size()];
        for(int i = 0; i < temp.length; i++){
            temp[i] = playListList.get(i);
        }
        for(int i = 0; i < temp.length; i++){
            System.out.println("Temp: "+i+" "+temp[i]);
        }
        String returnTitle = titleEditView.getText().toString();
        Intent returnIntent = new Intent();
        returnIntent.putExtra(RETURN_VALUE, returnTitle);
        returnIntent.putExtra(RETURN_PLAY_LIST, temp);
        setResult(RESULT_OK, returnIntent);
        finish();
    }
}

public class MusicAdapter extends
        RecyclerView.Adapter<MusicAdapter.ViewHolder>{

    private List<Song> songList;
    private ViewHolder viewHolder;
    public String smallOrLarge;

    public MusicAdapter(List<Song> songs){
        songList = songs;
    }

    public void setSmallOrLarge(String smallOrLarge) {
        this.smallOrLarge = smallOrLarge;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        Context context = parent.getContext();
        LayoutInflater inflater = LayoutInflater.from(context);
        if(smallOrLarge.equals("small")){
            View songView = inflater.inflate(R.layout.song_model_small, parent, false);
            viewHolder = new ViewHolder(songView);

        }
        if(smallOrLarge.equals("large")){
            View songView = inflater.inflate(R.layout.song_model_large, parent, false);
            viewHolder = new ViewHolder(songView);

        }

        return viewHolder;
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        Song song = songList.get(position);
        TextView songName = holder.songName;
        TextView songDuration = holder.songDuration;
        songName.setText(song.getSongName());
        songDuration.setText(song.getSongDuration());
    }

    @Override
    public int getItemCount() {
        return songList.size();
    }

    public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
        public TextView songName, songDuration;
        public  ViewHolder(View itemView){
            super(itemView);
            songName = itemView.findViewById(R.id.songName);
            songDuration = itemView.findViewById(R.id.songDuration);
            itemView.setOnClickListener(this);
        }

        @Override
        public void onClick(View view){
            int position = getAdapterPosition();
        }
    }


}

public class RecyclerViewItemClickListener implements RecyclerView.OnItemTouchListener {
    private OnItemClickListener mListener;

    public interface OnItemClickListener {
        public void onItemClick(View view, int position);
        public void onLongItemClick(View view, int position);
    }

    GestureDetector mGestureDetector;

    public RecyclerViewItemClickListener(Context context, final RecyclerView recyclerView, OnItemClickListener listener) {
        mListener = listener;
        mGestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
            @Override
            public boolean onSingleTapUp(MotionEvent e) {
                return true;
            }

            @Override
            public void onLongPress(MotionEvent e) {
                View child = recyclerView.findChildViewUnder(e.getX(), e.getY());
                if (child != null && mListener != null) {
                    mListener.onLongItemClick(child, recyclerView.getChildAdapterPosition(child));
                }
            }
        });
    }

    @Override public boolean onInterceptTouchEvent(RecyclerView view, MotionEvent e) {
        View childView = view.findChildViewUnder(e.getX(), e.getY());
        if (childView != null && mListener != null && mGestureDetector.onTouchEvent(e)) {
            mListener.onItemClick(childView, view.getChildAdapterPosition(childView));
            return true;
        }
        return false;
    }

    @Override public void onTouchEvent(RecyclerView view, MotionEvent motionEvent) { }

    @Override
    public void onRequestDisallowInterceptTouchEvent (boolean disallowIntercept){}
}