Ошибка в разности типов обьектов массива?

Error:(140, 55) error: incompatible types: List<String> cannot be converted to List<ListItem>

public class Adapter extends RecyclerView.Adapter<Adapter.MemViewHolder>{

    private List<String> listItems;
    private List<String> list;
    private Context context;
    private List<String> uid;
    private ProgressBar progressBar;
    private RecyclerView recyclerView;
    private TextView tv_likes, tv_dislikes, txtProgress;
    private ImageView memImage;
    private ImageButton button_like, button_dislike;

    public Adapter(List<String> uid){
        this.uid = uid;
    }

    @Override
    public MemViewHolder onCreateViewHolder(ViewGroup parent, int viewType){
        return new MemViewHolder(LayoutInflater.from(parent.getContext())
                .inflate(R.layout.recycler_item, parent, false));
    }

    @Override
    public void onBindViewHolder(MemViewHolder holder, int position){
        FirebaseDatabase database;
        DatabaseReference reference;
        String uid = list.get(position);
        database = FirebaseDatabase.getInstance();

        reference = database.getReference("Memes").child(uid).child("url");
        Log.i("DANIIL", uid);
        reference.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                String url = dataSnapshot.getValue(String.class);
                Glide.with(context).load(url).into(memImage);
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });

        reference = database.getReference("Memes").child(uid).child("tags");
        reference.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                String tags = dataSnapshot.getValue(String.class);
                char[] tags_c = tags.toCharArray();
                String tag;
                int i = 0;
                while (tags_c[i] != '@'){
                    tag = "";
                    while (tags_c[i] != '%'){
                        tag += tags_c[i];
                        i++;
                    }
                    listItems.add(tag);
                    i++;
                }
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });

        reference = database.getReference("Memes").child(uid).child("rate");
        reference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                String rate = dataSnapshot.getValue(String.class);
                char[] rate_c = rate.toCharArray();
                String likes_s = "", dislikes_s = "";
                boolean flag = false;
                for (int i = 0; i < rate_c.length; i++){
                    if (flag){
                        dislikes_s += rate_c[i];
                    }else{
                        if (rate_c[i] == '/'){
                            flag = true;
                        }else {
                            likes_s += rate_c[i];
                        }
                    }
                }
                tv_dislikes.setText(dislikes_s);
                tv_likes.setText(likes_s);
                Float likes = Float.valueOf(likes_s);
                Float dislikes = Float.valueOf(dislikes_s);

                Float ratingF = (likes / (likes + dislikes)) * 100;
                Integer rating = Math.round(ratingF);

                txtProgress.setText(rating.toString() + "%");
                progressBar.setProgress(rating);
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });


        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(context));
        listItems = new ArrayList<>();

        recyclerView.setLayoutManager(new LinearLayoutManager(context, LinearLayoutManager.HORIZONTAL,false));
        recyclerView.setAdapter(new HorizontalAdapter(listItems, context));//ошибка

public class HorizontalAdapter extends RecyclerView
        .Adapter<HorizontalAdapter.HorizontalViewHolder> {
    private Context context;
    List<ListItem> listItems;

    public HorizontalAdapter(List<ListItem> listItems, Context context) {
        this.context = context;
        this.listItems = listItems;

    }

    @Override
    public HorizontalViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(parent.getContext());
        View view = inflater.inflate(R.layout.tag_card, parent, false);

        return new HorizontalAdapter.HorizontalViewHolder(view);
    }

    @Override
    public void onBindViewHolder(HorizontalAdapter.HorizontalViewHolder holder, int position) {
        ListItem listItem = listItems.get(position);
        holder.tagText.setText(listItem.getTag());
    }

public class ListItem {
    private String tag;

    public ListItem(String tag){
        this.tag = tag;
    }

    public String getTag(){
        return tag;
    }