How to import image from gallery in android studio

Question

In this code, there are two images in stickerList, which come from drawable resources and can be set into my ImageView perfectly. Now I want to pick images from the gallery (rather than specific hardcoded drawables) and set any image I want. A new image from gallery which will override the previous or main one. How can i do that?

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

    }

    public class StickerAdapter extends RecyclerView.Adapter<StickerAdapter.ViewHolder> {

        int[] stickerList = new int[]{R.drawable.aa, R.drawable.bb};

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

        @Override
        public void onBindViewHolder(ViewHolder holder, int position) {
            holder.imgSticker.setImageResource(stickerList[position]);
        }

        @Override
        public int getItemCount() {
            return stickerList.length;
        }

        class ViewHolder extends RecyclerView.ViewHolder {
            ImageView imgSticker;

            ViewHolder(View itemView) {
                super(itemView);
                imgSticker = itemView.findViewById(R.id.imgSticker);

                itemView.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        if (mStickerListener != null) {
                            mStickerListener.onStickerClick(
                                    BitmapFactory.decodeResource(getResources(),
                                            stickerList[getLayoutPosition()]));
                        }
                        dismiss();
                    }
                });
            }
        }
    }