如何在内部匿名方法中写入 List（类 var）？

Question

全球理念： 从 REST API (https://jsonplaceholder.typicode.com/users/1) 获取数据，然后将数据添加到我的活动布局上的 ListView。

我在匿名类中获取数据（使用改造库），但如何将其写入 ArrayList 用户（即类 var）以实例化我的 ListViewAdapter？

public class CardFragmentUsers extends Fragment implements CardFragment {

    private CardView cardView;
    ArrayList<User> users = new ArrayList<User>();
    UsersListViewAdapter usersListViewAdapter;

    public static Fragment getInstance(int position){
        CardFragmentUsers f = new CardFragmentUsers();
        Bundle args = new Bundle();
        args.putInt("position", position);
        f.setArguments(args);

        return f;
    }

    @SuppressLint("DefaultLocale")
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater,
                             @Nullable ViewGroup container,
                             Bundle savedInstanceState) {

        View view = inflater.inflate(R.layout.item_viewpager_users, container, false);

        cardView = (CardView) view.findViewById(R.id.usersCardView);
        cardView.setMaxCardElevation(cardView.getCardElevation() * CardAdapter.MAX_ELEVATION_FACTOR);

        Button usersApplyButton = (Button)view.findViewById(R.id.usersApplyButton);

        usersApplyButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                View parent = (View)view.getParent();

                final TextView userCardviewGuideText = parent.findViewById(R.id.userCardviewGuideText);

                if (InternetConnection.checkConnection(getContext())){

                    ApiService api = RetroClient.getApiService();

                    // getting and filling data
//                    for (int i = 1; i <= 5; i++) {
                        Call<User> call = api.getUser(1);
                        /**
                         * Enqueue Callback will be call when get response...
                         */
                        call.enqueue(new Callback<User>() {
                            @Override
                            public void onResponse(Call<User> call, Response<User> response) {
                                if (response.isSuccessful()){
                                    userCardviewGuideText.setVisibility(View.INVISIBLE);
                                    User user = new User();
                                    user.setName(response.body().getName());
                                    user.setUsername(response.body().getUsername());
                                    users.add(user);
                                }else {
                                    userCardviewGuideText.setVisibility(View.VISIBLE);
                                    Toast.makeText(getActivity(), getString(R.string.smth_went_wrong), Toast.LENGTH_SHORT).show();
                                    return;
                                }
                            }

                            @Override
                            public void onFailure(Call<User> call, Throwable t) {

                            }
                        });

//                    }

                    usersListViewAdapter = new UsersListViewAdapter(parent.getContext(), users);
                    ListView usersListView = (ListView) parent.findViewById(R.id.usersListView);
                    usersListView.setAdapter(usersListViewAdapter);

                }else {
                    Toast.makeText(getActivity(), getString(R.string.no_internet_connection), Toast.LENGTH_SHORT).show();
                    userCardviewGuideText.setVisibility(View.VISIBLE);
                }

            }
        });

        return view;
    }


    public CardView getCardView() {return cardView;}
}

Answer 1

试试这个：

注意：我已经删除了一部分我没有更改的代码（为了清楚起见）。

public class CardFragmentUsers extends Fragment implements CardFragment {

    private CardView cardView;
    ArrayList<User> users = new ArrayList<User>();
    UsersListViewAdapter usersListViewAdapter;
    TextView userCardviewGuideText;

   // ...
   // Your code

    @SuppressLint("DefaultLocale")
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater,
                             @Nullable ViewGroup container,
                             Bundle savedInstanceState) {

        // ...
        // Your code

        // Define the TextView here
        userCardviewGuideText = findViewById(R.id.userCardviewGuideText);

        // Create your adapter outside the listener
        usersListViewAdapter = new UsersListViewAdapter(getContext(), users);
        ListView usersListView = (ListView) view.findViewById(R.id.usersListView);
        usersListView.setAdapter(usersListViewAdapter);

        usersApplyButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                if (InternetConnection.checkConnection(getContext())) {
                    retrieveUserInfoFromApi(); // Using a separate method make the code clearer

                } else {
                    Toast.makeText(getActivity(), getString(R.string.no_internet_connection), Toast.LENGTH_SHORT).show();
                    userCardviewGuideText.setVisibility(View.VISIBLE);
                }

            }
        });

        return view;
    }


    public CardView getCardView() {
        return cardView;
    }

    public void retrieveUserInfoFromApi() {
        ApiService api = RetroClient.getApiService();

        Call<User> call = api.getUser(1);
        /**
         * Enqueue Callback will be call when get response...
         */
        call.enqueue(new Callback<User>() {
            @Override
            public void onResponse(Call<User> call, Response<User> response) {
                if (response.isSuccessful()) {
                    userCardviewGuideText.setVisibility(View.INVISIBLE);
                    User user = new User();
                    user.setName(response.body().getName());
                    user.setUsername(response.body().getUsername());
                    users.add(user);
                    // Notify the adapter that the data have changed
                    usersListViewAdapter.notifyDataSetChanged();
                } else {
                    // ...
                    // Your code
                }
            }

            @Override
            public void onFailure(Call<User> call, Throwable t) {
                // Do something on error
            }
        });
    }
}