这个空数组有什么不好？

Question

即使在一个方法中接收 3 个元素，下一个类中的变量 adapter 仍然为空：

public class SaveListFrag extends Fragment implements RequestCallBack<Savings> {

private ListView saveListview;
private FloatingActionButton floatIcon;
public List<Saving> mItemArray;
private DragListView mDragListView;
private boolean isDeviceOnline;
SavingsAdapter adapter;
Savings data;
SQLiteDB bd;
int test = 0;
rtn pretest;

@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    return inflater.inflate(R.layout.fragment_savelist, container, false);
}

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    init(view);
    floatIcon = (FloatingActionButton) view.findViewById(R.id.floatIcon);
    addFloatButton();

}

private void init(View view) {

    mDragListView = (DragListView) view.findViewById(R.id.drag_list_view);
    mDragListView.getRecyclerView().setVerticalScrollBarEnabled(true);
    mDragListView.getRecyclerView().setHorizontalScrollBarEnabled(false);
    mDragListView.setDragListListener(new DragListView.DragListListenerAdapter() {
        @Override
        public void onItemDragStarted(int position) {
        }

        @Override
        public void onItemDragEnded(int fromPosition, int toPosition) {
            if (fromPosition != toPosition) {
            }
        }
    });

    isDeviceOnline = isInternetConnected();



    if (isDeviceOnline) {

        mItemArray = new ArrayList<>();
        makeRequest();

    }



    setupListRecyclerView();
}


private void addFloatButton() {
    floatIcon.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Intent intent = new Intent(getActivity(), ActivityChooseSaving.class);
            startActivity(intent);
        }
    });
}


private void setupListRecyclerView() {
    mDragListView.setLayoutManager(new LinearLayoutManager(getActivity()));
    adapter = new SavingsAdapter(mItemArray, R.layout.item_save_list, R.id.arrowlayout, false, getActivity());
    Log.d("Contenido item: ", mItemArray.toString());
    mDragListView.setAdapter(adapter, true);
    mDragListView.setCanDragHorizontally(false);

    mDragListView.setCustomDragItem(new MyDragItem(getActivity(), R.layout.item_save_list));
}

@Override
public void onRequestSuccess(Savings response) {

    if (mDragListView != null) {
        mDragListView.setScrollingEnabled(true);
    }


    for (int i = 0; i < response.data.size(); i++) {
            mItemArray.add(response.data.get(i));
        }

    adapter.notifyDataSetChanged();

    Log.d("Item ", String.valueOf(mItemArray.get(0)));

    isDeviceOnline = true;


}

@Override
public void onRequestFail(String message) {


    if (mDragListView != null) {
        mDragListView.setScrollingEnabled(false);
        Toast.makeText(this.getActivity(), getString(R.string.NO_internet), Toast.LENGTH_LONG).show();
        isDeviceOnline = false;
    }

}

@Override
public void onJSONException(String message) {

}

private boolean isInternetConnected() {
    ConnectivityManager cm = ((ConnectivityManager) getActivity().getSystemService(Context.CONNECTIVITY_SERVICE));

    if (cm.getActiveNetworkInfo() != null && cm.getActiveNetworkInfo().isConnected()) {
        return true;
    } else {
        return false;
    }
}

private void makeRequest() {
    if (mDragListView != null) {
        mDragListView.setScrollingEnabled(true);
    }
    ArrayList<BasicNameValuePair> params = new ArrayList<>();
    User user = CacheUtils.getUser(this.getActivity());
    params.add(new BasicNameValuePair("user_id", "3371"));
    Request<Savings> request = new Request<Savings>(this.getActivity(), CommonUtils.SERVICES.FETCH_ALL_SAVINGS, this, Savings.class, params);
    request.execute();

}



private void createOfflineDatabase(List<Saving> alstAccounts) {

    Intent syncServiceIntent = new Intent(getActivity(), SyncDatabaseService.class);
    syncServiceIntent.putExtra("accountsList", (java.io.Serializable) alstAccounts);
    syncServiceIntent.putExtra(CommonUtils.ACTION_TYPE, CommonUtils.ACTION_CREATE_OFFLINE_DATABASE);
    getActivity().startService(syncServiceIntent);
}



@SuppressWarnings("deprecation")
private static class MyDragItem extends DragItem {

    public MyDragItem(Context context, int layoutId) {
        super(context, layoutId);
    }

    @Override
    public void onBindDragView(View clickedView, View dragView) {
        dragView.setBackgroundColor(dragView.getResources().getColor(R.color.list_item_background));
    }
}

}

如您所见，我打印第一个“mItemArray”位置的值来检查内容，它存在，但由于某种原因，mItemArray 在主适配器中设置为空。

Answer 1

问题出在 SavingsAdapter 类中，构造函数中的列表未正确用于检索数据。