Question

我有一个片段，从另一个片段中检索名称标题，并且必须在此片段中显示详细信息。但我无法在Textview中显示数据。

这是我的 HistoryFragment

public class HistoryFragment extends Fragment {
public static final String TAG = "HISTORY_COUNTRY";
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
public static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
public int countryIDs;
ArrayList<AsiaCountry> asiaList = new ArrayList<>();
AsiaCountry asiaCountry;
int position;
Bundle bundle;
String content;
private List<AsiaCountry> item = Collections.emptyList();
private TextView historyContent;
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private HistoryOnFragmentInteractionListener mListener;

public HistoryFragment() {
    // Required empty public constructor
}

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);


    bundle = getActivity().getIntent().getExtras();
    if (bundle != null) {
        content = bundle.getString("name");
        Log.d("content", content.toString());
    }
    fetchData();
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.fragment_history, container, false);

     historyContent = (TextView) view.findViewById(R.id.content);



    historyContent.setText(asiaCountry.getHistory());
    Log.d("His", historyContent.getText().toString());

    return view;
}

private void fetchData() {
    WorldCountry worldCountry = new WorldCountry(getActivity());

    worldCountry.checkCopyDatabase();
    worldCountry.openDataBase();
    Log.d(ARG_PARAM1, "Database opened");

    try {

        Cursor cursor = worldCountry.QueryData("SELECT history FROM country WHERE name = ?" + content);
        Log.d("CURSOR", cursor.toString());

        if (cursor != null) {
            if (cursor.moveToFirst()) {
                do {
                    AsiaCountry asia = new AsiaCountry();
                    asia.setHistory(cursor.getString(cursor.getColumnIndex("history")));
                    Log.d(ARG_PARAM2, cursor.getString(0));
                    asiaList.add(asia);
                } while (cursor.moveToNext());
                worldCountry.close();
            }

        }

    } catch (SQLException e) {
        e.printStackTrace();
        Log.d("TAG", e.getMessage());

    }


}


// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
    if (mListener != null) {
        mListener.historyOnFragmentInteraction(uri);
    }
}

@Override
public void onAttach(Context context) {
    super.onAttach(context);
    if (context instanceof HistoryOnFragmentInteractionListener) {
        mListener = (HistoryOnFragmentInteractionListener) context;
    } else {
        throw new RuntimeException(context.toString()
                + " must implement OnFragmentInteractionListener");
    }
}

@Override
public void onDetach() {
    super.onDetach();
    mListener = null;
}


public interface HistoryOnFragmentInteractionListener {
    // TODO: Update argument type and name
    void historyOnFragmentInteraction(Uri uri);
}

}

在上面的代码中，我从数据库中检索数据，我希望在Textview中显示，但我不能。

伙计们我认为我的冒犯是错误的，因为我没有检索历史记录列，因此，asiaList不会添加asia.setHistory（cursor.getString（0））;也许我错了。我必须告诉光标检索历史列，其中name = content。

Answer 1

asiaCountry没有内容。

  historyContent.setText(asiaCountry.getHistory());

尝试通过提供所需的位置来获取列表中的内容。对于前。

     historyContent.setText(asiaList.get(0).getHistory);

Answer 2

试试这个：

if(asiaList != null && asiaList.size()>0){
  for(int i=0;i<asiaList.size();i++){
     historyContent.append(asiaList.get(i).getHistory()+"\n");
  }
}

而不是

historyContent.setText(asiaCountry.getHistory());

在您的查询中尝试此操作

Cursor cursor = worldCountry.QueryData("SELECT history FROM country WHERE name = '"+content+"'");

如何在textview中显示来自数据库的数据

2 个答案: