仅在恢复活动时获取 IndexOutOfBoundsException

Question

My problem is that my App crashes when the MainActivity gets resumed.
The error is an IndexOutOfBoundsException , unfortunately without a specific line. And the error says Index: 0, Size: 0 .

As I know this means that my ArrayList is null and I call it before I initialize it. But I searched since days after that case. I didn't find anything.

So first here is the Error:

08-28 13:10:24.232 18741-18741/com.test.test.test E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.test.test.test, PID: 18741
java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
    at java.util.ArrayList.get(ArrayList.java:411)
    at com.firebase.ui.common.BaseObservableSnapshotArray.getSnapshot(BaseObservableSnapshotArray.java:70)
    at com.firebase.ui.common.BaseObservableSnapshotArray.get(BaseObservableSnapshotArray.java:52)
    at com.firebase.ui.firestore.FirestoreRecyclerAdapter.getItem(FirestoreRecyclerAdapter.java:83)
    at com.firebase.ui.firestore.FirestoreRecyclerAdapter.onBindViewHolder(FirestoreRecyclerAdapter.java:125)
    at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6673)
    at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6714)
    at android.support.v7.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5647)
    at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5913)
    at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5752)
    at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5748)
    at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2232)
    at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1559)
    at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1519)
    at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:614)
    at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3812)
    at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3529)
    at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:4082)
    at android.view.View.layout(View.java:17689)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.support.constraint.ConstraintLayout.onLayout(ConstraintLayout.java:1858)
    at android.view.View.layout(View.java:17689)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1079)
    at android.view.View.layout(View.java:17689)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1079)
    at android.view.View.layout(View.java:17689)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at android.view.View.layout(View.java:17689)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.support.design.widget.CoordinatorLayout.layoutChild(CoordinatorLayout.java:1191)
    at android.support.design.widget.CoordinatorLayout.onLayoutChild(CoordinatorLayout.java:876)
    at android.support.design.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:895)
    at android.view.View.layout(View.java:17689)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:1171)
    at android.view.View.layout(View.java:17689)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at android.view.View.layout(View.java:17689)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
    at android.view.View.layout(View.java:17689)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at android.view.View.layout(View.java:17689)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
    at android.view.View.layout(View.java:17689)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at com.android.internal.policy.DecorView.onLayout(DecorView.java:730)
    at android.view.View.layout(View.java:17689)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2346)
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2068)
    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1254)
    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6343)
    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:874)
    at android.view.Choreographer.doCallbacks(Choreographer.java:686)
    at android.view.Choreographer.doFrame(Choreographer.java:621)
    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:860)
    at android.os.Handler.handleCallback(Handler.java:751)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:241)
    at android.app.ActivityThread.main(ActivityThread.java:6274)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

And here is a snippet of my Code:
MainActivity:

public class MainActivity extends AppCompatActivity implements RecyclerItemTouchHelper.RecyclerItemTouchHelperListener, NoteListAdapter.NotesAdapterListener {

private FirebaseAuth mFirebaseAuth;
public FirebaseUser mFirebaseUser;
private FirebaseFirestore db;

private RecyclerView recyclerView;
private RecyclerView.LayoutManager recyclerViewLayoutManager;
public NoteListAdapter adapter;
private List<Note> notesList = new ArrayList<>();

private ListenerRegistration firestoreListener;
private RecyclerItemTouchHelper.RecyclerItemTouchHelperListener listener;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mFirebaseAuth = FirebaseAuth.getInstance();
    mFirebaseUser = mFirebaseAuth.getInstance().getCurrentUser();
    db = FirebaseFirestore.getInstance();

    recyclerView = findViewById(R.id.rvNoteList);

    FirebaseFirestoreSettings settings = new FirebaseFirestoreSettings.Builder().setPersistenceEnabled(true).build();
    db.setFirestoreSettings(settings);

    Query query = db.collection("users").document(firebase_user_uid).collection("notes");
    FirestoreRecyclerOptions<Note> response = new FirestoreRecyclerOptions.Builder<Note>().setQuery(query, Note.class).build();
    adapter = new NoteListAdapter(notesList, response, MainActivity.this, MainActivity.this);

    recyclerViewLayoutManager = new LinearLayoutManager(MainActivity.this, LinearLayoutManager.VERTICAL, false);
    recyclerView.setLayoutManager(recyclerViewLayoutManager);
    recyclerView.setItemAnimator(new DefaultItemAnimator());
    recyclerView.addItemDecoration(new CustomRecyclerViewDivider(this, LinearLayoutManager.VERTICAL, 16));

    recyclerView.setAdapter(adapter);

    ItemTouchHelper.SimpleCallback itemTouchHelperCallback = new RecyclerItemTouchHelper(0, ItemTouchHelper.LEFT, MainActivity.this);
    new ItemTouchHelper(itemTouchHelperCallback).attachToRecyclerView(recyclerView);

    firestoreListener = db.collection("users").document(firebase_user_uid).collection("notes")
            .addSnapshotListener(new EventListener<QuerySnapshot>() {
                @Override
                public void onEvent(QuerySnapshot documentSnapshots, FirebaseFirestoreException e) {
                    if (e != null) {
                        Log.e("LOL", "Listen failed!", e);
                        return;
                    }

                    notesList.clear();

                    for (DocumentSnapshot doc : documentSnapshots) {
                        Note note = doc.toObject(Note.class);
                        note.setId(doc.getId());
                        notesList.add(note);
                    }
                }
            });

    recyclerView.addOnItemTouchListener(new RecyclerViewTouchListener(getApplicationContext(), recyclerView, new RecyclerViewTouchListener.ClickListener() {
        @Override
        public void onClick(View view, int position) {
            if (notesList != null || notesList.size() <= 0) {
                Note note = notesList.get(position);
                updateNote(note);
            }
        }

        @Override
        public void onLongClick(View view, int position) {

        }
    }));

}

@Override
public void onStart() {
    super.onStart();
    if (adapter != null) {
        adapter.startListening();
    }
}

@Override
public void onStop() {
    super.onStop();
    if (adapter != null) {
        adapter.stopListening();
    }
}

@Override
protected void onResume() {
    super.onResume();

    if (adapter != null) {
        adapter.startListening();
    }
}}  

And here is the NoteListAdapter:

public class NoteListAdapter extends FirestoreRecyclerAdapter<Note, NoteListAdapter.NoteViewHolder> implements Filterable{

private List<Note> notesList;
private List<Note> notesListFiltered;
private NotesAdapterListener listener;
private Context context;

public class NoteViewHolder extends RecyclerView.ViewHolder {

    public TextView title, content;
    public ImageView bg_note_image;
    public RelativeLayout viewBackground, viewForeground;

    public NoteViewHolder(View view) {
        super(view);
        title = view.findViewById(R.id.tvTitle);
        content = view.findViewById(R.id.tvContent);
        bg_note_image = view.findViewById(R.id.note_image_view);
        viewBackground = view.findViewById(R.id.view_background);
        viewForeground = view.findViewById(R.id.view_foreground);

        view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                listener.onNoteSelected(notesListFiltered.get(getAdapterPosition()));
            }
        });
    }
}

public NoteListAdapter(List<Note> notesList, FirestoreRecyclerOptions<Note> response, Context co, NotesAdapterListener listener) {
    super(response);
    context = co;
    this.listener = listener;
    this.notesList = notesList;
    this.notesListFiltered = notesList;
}

@Override
protected void onBindViewHolder(NoteViewHolder holder, int position, Note model) {
    if (notesListFiltered != null || notesList != null) {
        final Note note = notesListFiltered.get(position);

        holder.title.setText(note.getTitle());
        holder.content.setText(note.getContent());
        if (note.getNote_image_url() != null) {
            Glide.with(context).load(note.getNote_image_url()).into(holder.bg_note_image);
            holder.bg_note_image.setVisibility(View.VISIBLE);
        }
    }
}

@Override
public NoteViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_note_view, parent, false);
    return new NoteViewHolder(view);
}

@Override
public void onError(FirebaseFirestoreException e) {
    Log.e("LOL", e.getMessage());
}

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

public void removeItem(int position) {
    notesList.remove(position);
    // notify the item removed by position
    // to perform recycler view delete animations
    // NOTE: don't call notifyDataSetChanged()
    notifyItemRemoved(position);
}

public void restoreItem(Note item, int position) {
    notesList.add(position, item);
    // notify item added by position
    notifyItemInserted(position);
}

@Override
public Filter getFilter() {
    return new Filter() {
        @Override
        protected FilterResults performFiltering(CharSequence charSequence) {
            String charString = charSequence.toString();
            if (charString.isEmpty()) {
                notesListFiltered = notesList;
            } else {
                List<Note> filteredList = new ArrayList<>();
                for (Note row : notesList) {

                    // name match condition. this might differ depending on your requirement
                    // here we are looking for name or phone number match
                    if (row.getTitle().toLowerCase().contains(charString.toLowerCase()) || row.getContent().toLowerCase().contains(charString.toLowerCase())) {
                        filteredList.add(row);
                    }
                }

                notesListFiltered = filteredList;
            }

            FilterResults filterResults = new FilterResults();
            filterResults.values = notesListFiltered;
            return filterResults;
        }

        @Override
        protected void publishResults(CharSequence charSequence, FilterResults filterResults) {
            notesListFiltered = (ArrayList<Note>) filterResults.values;
            notifyDataSetChanged();
        }
    };
}

public interface NotesAdapterListener {
    void onNoteSelected(Note note);
}}

And additionally I tried this to find a specific line, but without any success:

@Override
protected void onResume() {
    try {
        super.onResume();
    } catch (Exception e) {
        e.printStackTrace();
        Log.d("LOL", e.getMessage(), e);
    }
}  

I really hope anybody has a solution for my problem, because I really don't know how to fix this since one week.

Thanks in advance.

Answer 1

Check below code. Hope it will be helpful for you. You need to replace all firebase firestore logic to onResume() method.

public class MainActivity extends AppCompatActivity implements RecyclerItemTouchHelper.RecyclerItemTouchHelperListener, NoteListAdapter.NotesAdapterListener {

private FirebaseAuth mFirebaseAuth;
public FirebaseUser mFirebaseUser;
private FirebaseFirestore db;

private RecyclerView recyclerView;
private RecyclerView.LayoutManager recyclerViewLayoutManager;
public NoteListAdapter adapter;
private List<Note> notesList = new ArrayList<>();

private ListenerRegistration firestoreListener;
private RecyclerItemTouchHelper.RecyclerItemTouchHelperListener listener;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    recyclerView = findViewById(R.id.rvNoteList);



}

@Override
public void onStart() {
    super.onStart();
    if (adapter != null) {
        adapter.startListening();
    }
}

@Override
public void onStop() {
    super.onStop();
    if (adapter != null) {
        adapter.stopListening();
    }
}

@Override
protected void onResume() {
    super.onResume();
    mFirebaseAuth = FirebaseAuth.getInstance();
    mFirebaseUser = mFirebaseAuth.getInstance().getCurrentUser();
    db = FirebaseFirestore.getInstance();

    if (adapter != null) {
        adapter.startListening();
    }
       FirebaseFirestoreSettings settings = new FirebaseFirestoreSettings.Builder().setPersistenceEnabled(true).build();
    db.setFirestoreSettings(settings);

    Query query = db.collection("users").document(firebase_user_uid).collection("notes");
    FirestoreRecyclerOptions<Note> response = new FirestoreRecyclerOptions.Builder<Note>().setQuery(query, Note.class).build();
    adapter = new NoteListAdapter(notesList, response, MainActivity.this, MainActivity.this);

    recyclerViewLayoutManager = new LinearLayoutManager(MainActivity.this, LinearLayoutManager.VERTICAL, false);
    recyclerView.setLayoutManager(recyclerViewLayoutManager);
    recyclerView.setItemAnimator(new DefaultItemAnimator());
    recyclerView.addItemDecoration(new CustomRecyclerViewDivider(this, LinearLayoutManager.VERTICAL, 16));

    recyclerView.setAdapter(adapter);

    ItemTouchHelper.SimpleCallback itemTouchHelperCallback = new RecyclerItemTouchHelper(0, ItemTouchHelper.LEFT, MainActivity.this);
    new ItemTouchHelper(itemTouchHelperCallback).attachToRecyclerView(recyclerView);

    firestoreListener = db.collection("users").document(firebase_user_uid).collection("notes")
            .addSnapshotListener(new EventListener<QuerySnapshot>() {
                @Override
                public void onEvent(QuerySnapshot documentSnapshots, FirebaseFirestoreException e) {
                    if (e != null) {
                        Log.e("LOL", "Listen failed!", e);
                        return;
                    }

                    notesList.clear();

                    for (DocumentSnapshot doc : documentSnapshots) {
                        Note note = doc.toObject(Note.class);
                        note.setId(doc.getId());
                        notesList.add(note);
                    }
                }
            });

    recyclerView.addOnItemTouchListener(new RecyclerViewTouchListener(getApplicationContext(), recyclerView, new RecyclerViewTouchListener.ClickListener() {
        @Override
        public void onClick(View view, int position) {
            if (notesList != null || notesList.size() <= 0) {
                Note note = notesList.get(position);
                updateNote(note);
            }
        }

        @Override
        public void onLongClick(View view, int position) {

        }
    }))


}}  

Answer 2

just change your code to :

                notesList.clear();

                for (DocumentSnapshot doc : documentSnapshots) {
                    Note note = doc.toObject(Note.class);
                    note.setId(doc.getId());
                    notesList.add(note);

instead use,

firestoreListener = db.collection("users").document(firebase_user_uid).collection("notes")
            .addSnapshotListener(new EventListener<QuerySnapshot>() {
                @Override
                public void onEvent(QuerySnapshot documentSnapshots, FirebaseFirestoreException e) {
                    if (e != null) {
                        Log.e("LOL", "Listen failed!", e);
                        notesList=new ArrayList();    
                    for (DocumentSnapshot doc : documentSnapshots) {
                        Note note = doc.toObject(Note.class);
                        note.setId(doc.getId());
                        notesList.add(note);
                    }
                 }   
                }
            });