Vfrdtyky

I have done something doing that when arraylist.day == calendar.dayofmonth, it programmatically scroll into the arraylist position but when i start my activity i've got this error : "Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference".

Can someone help me please ?

Planning.java :

    public void setUpRecyclerView(){

    recyclerView = findViewById(R.id.recyclerView);

    recyclerView.setHasFixedSize(true);

    recyclerView.setLayoutManager(new LinearLayoutManager(this));

}



private void setUpFirebase(){

    db = FirebaseFirestore.getInstance();

}



private void loadDataFromFirebase(){

    if(eventsArrayList.size()>0){

        eventsArrayList.clear();}

    db.collection("Planning").get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {

        @Override

        public void onComplete(@NonNull Task<QuerySnapshot> task) {

            for(DocumentSnapshot querySnapshot: task.getResult()){

                Events Nom = new Events(querySnapshot.getString("Nom"),querySnapshot.getString("Lieu"),querySnapshot.getString("Heure"),querySnapshot.getString("Minute"),querySnapshot.getString("Day"));

                eventsArrayList.add(Nom);

            }

            tvLoad.setVisibility(View.GONE);

            progressBar.setVisibility(View.GONE);

            adapter = new MyRecyclerViewAdapter(Planning.this, eventsArrayList);

            recyclerView.setAdapter(adapter);

            recyclerView.setItemAnimator(new DefaultItemAnimator());

        }

}



    public void ScrollTo(int position){

    recyclerView.scrollToPosition(position);

}

}

RecyclerViewAdapter :

    @Override

public void onBindViewHolder(@NonNull MyRecyclerViewHolder holder, int position) {

    Calendar cal = Calendar.getInstance();

    holder.tvLieu.setVisibility(View.VISIBLE);

    holder.tvDate.setVisibility(View.VISIBLE);

    holder.cardView.setCardBackgroundColor(Color.WHITE);

    LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) holder.tvNom.getLayoutParams();

    params.gravity = Gravity.START;

    holder.tvNom.setLayoutParams(params);

    if(eventsArrayList.get(position).getDay().equals(String.valueOf(cal.get(Calendar.DAY_OF_MONTH)))) { planning.ScrollTo(position); }

    holder.tvNom.setText(eventsArrayList.get(position).getNom());

    holder.tvLieu.setText(eventsArrayList.get(position).getLieu());

    holder.tvDate.setText(eventsArrayList.get(position).getHeure() + "h" + eventsArrayList.get(position).getMinute());

    if(eventsArrayList.get(position).getHeure().equals("")){

        holder.tvDate.setVisibility(View.GONE);

        holder.tvLieu.setVisibility(View.GONE);

        params.gravity = Gravity.CENTER;

        holder.tvNom.setLayoutParams(params);

        holder.cardView.setCardBackgroundColor(Color.parseColor("#227c97"));

    }

}

Without a proper stack trace, I could only assume either eventsArrayList.get(position).getHeure() or eventsArrayList.get(position).getDay() has returned null.

If you think it crashes at eventsArrayList.get(position).getHeure(), you could try TextUtils.isEmpty instead, which also checks for null:

if(TextUtils.isEmpty(eventsArrayList.get(position).getHeure())){

    holder.tvDate.setVisibility(View.GONE);

    holder.tvLieu.setVisibility(View.GONE);

    params.gravity = Gravity.CENTER;

    holder.tvNom.setLayoutParams(params);

    holder.cardView.setCardBackgroundColor(Color.parseColor("#227c97"));

} else {

    // also you should update tvDate, tvLieu, tvNom and cardView

    // or you would get weird behaviour when the view holder is being recycled

}

If you think it crashes at eventsArrayList.get(position).getDay(), you could use TextUtils.equals:

if (TextUtils.equals(eventsArrayList.get(position).getDay(), String.valueOf(cal.get(Calendar.DAY_OF_MONTH)))

Most importantly, I'd not recommend RecyclerView.scrollTo in onBindViewHolder, it's a bad practice, you should perform this action else where. And maybe because you're trying to match a condition, and it can return null for other positions, so NPE occurs.