Odtnhj

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.