问尝试调用空对象引用上的接口方法'int java.util.List.size()‘-同时调用retrofit

EN

private List<DellTransportList> customers;

    public DellTransportAdapter(List<DellTransportList> list) {
        this.customers = list;
    }

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

    @Override
    public void onBindViewHolder(@NonNull MyDriveViewHolder holder, int position) {
        DellTransportList customer = customers.get(holder.getAdapterPosition());

        TextView dataText = holder.mEmployeeId;
        TextView dataName = holder.mName;

        dataText.setText(customer.getEmployeeid());
        dataName.setText(customer.getName());

    }

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

    public class MyDriveViewHolder extends RecyclerView.ViewHolder {

        public TextView mName, mEmployeeId;

        public MyDriveViewHolder(View view) {
            super(view);
            mName = view.findViewById(R.id.mtv_view);
            mEmployeeId = view.findViewById(R.id.mtv_data_view);
        }
    }  

// RecyclerView
    mRecycler = findViewById(R.id.rv_drive);
    mRecycler.setHasFixedSize(true);
    mApiInterface = RetrofitInstance.getRetrofitInstance().create(DellTransportApiInterface.class);
    mList = new ArrayList();
    Call<List<DellTransportList>> call = mApiInterface.getcustomerName();
    call.enqueue(new Callback<List<DellTransportList>>() {
        @Override
        public void onResponse(@NotNull Call<List<DellTransportList>> call, @NotNull Response<List<DellTransportList>> response) {
            mList = response.body();
            mAdapter = new DellTransportAdapter(mList);
            mRecycler.setAdapter(mAdapter);
            mRecycler.setLayoutManager(new LinearLayoutManager(DriveActivity.this));
            mAdapter.notifyDataSetChanged();
            // Toast.makeText(getApplicationContext(),response,Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onFailure(@NotNull Call<List<DellTransportList>> call, @NotNull Throwable t) {
        }
    });
}