ERROR - "Cannot resolve symbol 'context" when trying to load images using Glide in RecyclerView

Question

I have built a note-taking app with Room, ViewModel, LiveData, and RecyclerView using this tutorial. Everything is working very well. However, when I began to implement the ability to select an image for each note, the RecyclerView became really laggy and slow as more notes with images were added.

After some research, I discovered that using image loading frameworks like Glide and Picasso can make loading faster. So, I tried using Glide to load images from a Uri into the RecyclerView items.

NoteAdapter.java

public class NoteAdapter extends ListAdapter<Note, NoteAdapter.NoteHolder> {

Context context;

public NoteAdapter() {
    super(DIFF_CALLBACK);
}

private static final DiffUtil.ItemCallback<Note> DIFF_CALLBACK = new DiffUtil.ItemCallback<Note>() {
    @Override
    public boolean areItemsTheSame(@NonNull Note note, @NonNull Note t1) {
        return note.getId() == t1.getId();
    }

    @Override
    public boolean areContentsTheSame(@NonNull Note note, @NonNull Note t1) {
        return note.getTitle().equals(t1.getTitle()) &&  note.getDescription().equals(t1.getDescription()) && note.getImageUri().equals(t1.getImageUri());
    }
};

private OnItemClickListener listener;

@NonNull
@Override
public NoteHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
    View itemView = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.note_item, viewGroup, false);
    return new NoteHolder(itemView);
}

@Override
public void onBindViewHolder(@NonNull NoteHolder noteHolder, int i) {
    Note currentNote = getItem(i);
    noteHolder.textViewTitle.setText(currentNote.getTitle());
    noteHolder.textViewDescription.setText(currentNote.getDescription());

    Glide.with(context)
            .load(Uri.parse(currentNote.getImageUri()))
            .fit()
            .centerCrop()
            .into(noteHolder.image);

}

public Note getNoteAt(int position) {
    return getItem(position);
}

class NoteHolder extends RecyclerView.ViewHolder {
    private TextView textViewTitle;
    private TextView textViewDescription;
    private ImageView image;

    public NoteHolder(@NonNull View itemView) {
        super(itemView);
        textViewTitle = itemView.findViewById(R.id.text_view_title);
        textViewDescription = itemView.findViewById(R.id.text_view_description);
        image = itemView.findViewById(R.id.image_view);

        itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                int position = getAdapterPosition();

                if (listener != null && position != RecyclerView.NO_POSITION) {
                    listener.onItemClick(getItem(position));
                }
            }
        });
    }
}

public interface OnItemClickListener {
    void onItemClick(Note note);
}

public void setOnItemClickListener(OnItemClickListener listener) {
    this.listener = listener;
}

}

However, Android Studio gives me the following error - Cannot resolve symbol 'context'. My question is, what context should I be passing in for this argument? Also, any other suggestions to make the RecyclerView faster when loading images would be greatly appreciated. Thanks!

PS - I am not a professional whatsoever, and only program as a hobby, so I apologize for any misused terms.

Answer 1

you need to define global variable

 Context context ;

and change your code to the following :

public class NoteAdapter extends ListAdapter<Note, NoteAdapter.NoteHolder> {

....
Context context;
@NonNull
@Override
public NoteHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
    context = viewGroup.getContext();
View itemView = LayoutInflater.from(context).inflate(R.layout.note_item, viewGroup, false);
    return new NoteHolder(itemView);
}

@Override
public void onBindViewHolder(@NonNull NoteHolder noteHolder, int i) {
    Note currentNote = getItem(i);
    noteHolder.textViewTitle.setText(currentNote.getTitle());
    noteHolder.textViewDescription.setText(currentNote.getDescription());

    Glide.with(context)
            .load(Uri.parse(currentNote.getImageUri()))
            .fit()
            .centerCrop()
            .into(noteHolder.image);

}

....

}