Question

我首先要说我认为我想做的事情是不可能的（已经读过我认为是ISO C99的相关部分），但是这里是我现在所拥有的大致想法：

public class Help extends Fragment {
    View myView;
    Button btn;
    TextView txtview;
    private RecyclerView rview;
    private RecyclerView.Adapter rviewadap;
    ArrayList<MessagesModel> mm = new ArrayList<>();

    public void initMessages() {

        mm.add(new MessagesModel("Hello this is a test", "12:41"));
        mm.add(new MessagesModel("This is another test", "12:43"));
        mm.add(new MessagesModel("How are you doing today", "12:43"));
    }

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        myView = inflater.inflate(R.layout.help, container, false);
        initMessages();

        this.rview = myView.findViewById(R.id.reyclerview_message_list);
        txtview = myView.findViewById(R.id.edittext_chatbox);
        RecyclerView.LayoutManager layout = new LinearLayoutManager(this.getActivity());
        this.rview.setLayoutManager(layout);

        rviewadap = new MessagesAdapter(mm);
        this.rview.setAdapter(rviewadap);

        btn = myView.findViewById(R.id.button_chatbox_send);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                mm.add(new MessagesModel(""+txtview.getText().toString(), "12:41"));
                rviewadap.notifyDataSetChanged();
            }
        });
        return myView;
    }

    public class MessagesModel{
        String varMessage,varTime;
        public MessagesModel(String varMessage,String varTime){
            this.varMessage = varMessage;
            this.varTime = varTime;
        }
    }

    public class MessagesAdapter extends RecyclerView.Adapter<MessagesAdapter.ViewHolder> {
        public ArrayList<MessagesModel> mm;

        public MessagesAdapter(ArrayList<MessagesModel> mm) {
            this.mm = mm;
        }

        @NonNull
        @Override
        public ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {

            View view = (View) LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.row_weather, viewGroup, false);
            return new ViewHolder(view);
        }

        @Override
        public void onBindViewHolder(@NonNull final ViewHolder viewHolder, int i) {
            viewHolder.message.setText(mm.get(i).varMessage);
            viewHolder.time.setText(mm.get(i).varTime);
        }

        @Override
        public int getItemCount() {
            if(mm != null) {
                return mm.size();
            }else {
                return 0;
            }
        }

        public class ViewHolder extends RecyclerView.ViewHolder {
            public TextView message;
            public TextView time;

            public ViewHolder(@NonNull View view) {
                super(view);
                message = view.findViewById(R.id.day_txt);
                System.out.println("body message id is: "+message);
                time = view.findViewById(R.id.temp_txt);
            }
        }
    }
}

这在C99 / C11中有效，但是我真正想要的是将name参数放到FOO_INITIALIZER宏中。有可能吗？

我知道这行不通：

struct foo {
    int x;
    int *y;
};

#define FOO_INITIALIZER(name) \
{                             \
    .x = 1,                   \
    .y = &(name).x,           \
}

struct foo bar = FOO_INITIALIZER(bar);

如果可以的话，我应该查看ISO / IEC 9899：TC3的哪个部分？

Answer 1

无法用标准C语言实现所需的功能。您可以继续通过offsetof传递名称（但不适用于嵌套对象）或存储偏移量而不是指针（在很大程度上取决于应用程序），而不是指针。

C99 / C11自引用子对象可以初始化吗？

1 个答案: