java - 作为原始类型 ListAdapter 的成员，对submitList(List) 进行未经检查的调用

Question

我一直在复制Sunflower android 架构最佳实践应用程序，到目前为止缓慢但成功，虽然我的代码可以工作，但它显示一条未经检查的消息，所以我运行了它要求的命令，它说的是这样的:

[unchecked] unchecked call to submitList(List) as a member of the raw type ListAdapter where T is a type-variable: T extends Object declared in class ListAdapter

这可能不重要，但它让我很恼火，我用作引用的那个从来没有围绕 ListAdapter 或任何东西有任何 <> 并且没有警告，所以我不确定为什么我的。

我的 fragment :

public class NewsFeedFragment extends Fragment {

    private PinViewModel viewModel;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        FragmentNewsFeedBinding binding = FragmentNewsFeedBinding.inflate(inflater, container, false);
        PinViewModelFactory factory = InjectorUtils.providePinListViewModelFactory(getContext());
        ListAdapter adapter = new PinListAdapter();
        binding.pinList.setAdapter(adapter);
        this.viewModel = ViewModelProviders.of(this, factory).get(PinViewModel.class);
        subscribeUi(adapter);
        return binding.getRoot();
    }

    private void subscribeUi(ListAdapter adapter) {
        this.viewModel.pins.observe(getViewLifecycleOwner(), pins -> {
            if (pins != null) {
                adapter.submitList(pins);
            }
        });
    }
}

我的 View 模型:

public class PinViewModel extends ViewModel {

    private PinRepository pinRepository;

    public LiveData<List<Pin>> pins;

    PinViewModel(@NonNull PinRepository pinRepository) {
        this.pinRepository = pinRepository;
        this.pins = this.pinRepository.getPins();
    }
}

我的适配器:

public class PinListAdapter extends ListAdapter<Pin, PinListAdapter.ViewHolder>{

    public PinListAdapter() {
        super(new PinDiffCallback());
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        return new ViewHolder(ListItemPinBinding.inflate(
                LayoutInflater.from(parent.getContext()), parent, false));
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        Pin pin = getItem(position);
        holder.bind(pin);
        holder.itemView.setTag(pin);
    }

    static class ViewHolder extends RecyclerView.ViewHolder {
        private ListItemPinBinding binding;

        ViewHolder(@NonNull ListItemPinBinding binding) {
            super(binding.getRoot());
            this.binding = binding;
        }

        void bind(Pin item) {
            binding.setPin(item);
            binding.executePendingBindings();
        }
    }

    static class PinDiffCallback extends DiffUtil.ItemCallback<Pin> {

        @Override
        public boolean areItemsTheSame(@NonNull Pin oldItem, @NonNull Pin newItem) {
            return oldItem.getId() == (newItem.getId());
        }

        @Override
        public boolean areContentsTheSame(@NonNull Pin oldItem, @NonNull Pin newItem) {
            return oldItem == newItem;
        }
    }
}

Answer 1

您正在使用

ListAdapter adapter = new PinListAdapter();

这会丢弃类型信息 PinListAdapter 。具体来说，ListAdapter<Pin, PinListAdapter.ViewHolder>通用类型信息。因此你的subscribeUi不知道你的ListAdapter获取 Pin 的列表对象，然后您会收到所遇到的错误。

您可以将适配器更改为 PinListAdapter您将获得所需的类型信息。