從數據庫中刪除項目後更新片段中的列表視圖

Question

刪除項目後，我無法更新Fragment中的ListView。 我可以透過

@Override 
public void onResume(){ 
    super.onResume(); 
    getActivity().getSupportLoaderManager().getLoader(0).forceLoad(); 
} 

添加一個條目和更新Listview但切除後，我需要滾動Fragments遠程內容丟失：

public boolean onContextItemSelected(MenuItem item) { 
    if (item.getItemId() == 1) { 
     // получаем из пункта контекстного меню данные по пункту списка 
     AdapterView.AdapterContextMenuInfo acmi = (AdapterView.AdapterContextMenuInfo) item 
       .getMenuInfo(); 
     db.deleteRow(acmi.id); 
     getActivity().getSupportLoaderManager().getLoader(0).forceLoad(); 
     scAdapter.notifyDataSetChanged(); 
     return true; 
    } 
    return super.onContextItemSelected(item); 
} 

在這裏，所有的代碼

import android.content.Context; 
import android.database.Cursor; 
import android.os.Bundle; 
import android.support.v4.app.Fragment; 
import android.support.v4.app.LoaderManager.LoaderCallbacks; 
import android.support.v4.content.*; 
import android.view.*; 
import android.widget.*; 

import comzaqxs.vk.com.fucktheorientation.*; 

public class MonthFragment extends Fragment implements LoaderCallbacks<Cursor> { 

    public static final String[] months = { "Январь", "Февраль", "Март", "Апрель", "Май", 
      "Июнь", "Июль", "Август", "Сентябрь", "Октябрь", "Ноябрь", "Декабрь" }; 
    public static final String[] years = { "2015", "2016", "2017", "2018", "2019", "2020", 
      "2021", "2022", "2023", "2024", "2025", "2026", "2027", "2028", "2029", "2030" }; 
    private static final int CM_DELETE_ID = 1; 
    ListView lvMonth; 
    DBAdapter db; 
    SimpleCursorAdapter scAdapter; 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
      Bundle savedInstanceState) { 
     View v = inflater.inflate(R.layout.month_item, container, false); 

     db = new DBAdapter(getActivity()); 
     db.open(); 
     String[] fromFieldNames = new String[] { DBAdapter.KEY_DATE, DBAdapter.KEY_AREA, 
       DBAdapter.KEY_PASSENGER }; 
     int[] toViewsID = new int[] { R.id.tvItemDate, R.id.tvItemArea, R.id.tvItemPassenger }; 
     scAdapter = new SimpleCursorAdapter(getActivity(), R.layout.item, null, 
       fromFieldNames, toViewsID, 0); 

     lvMonth = (ListView) v.findViewById(R.id.lvMonth); 
     lvMonth.setAdapter(scAdapter); 
     lvMonth.setBackgroundColor(0xffFFFFFF); 
     registerForContextMenu(lvMonth); 
     getActivity().getSupportLoaderManager().initLoader(0, null, this); 

     Spinner monthsSpinner = (Spinner) v.findViewById(R.id.monthSpinner); 
     monthsSpinner.setBackgroundColor(0xffF44336); 
     ArrayAdapter<String> monthsAdapter = new ArrayAdapter<>(getActivity(), 
       R.layout.my_spinner_gravity_center, months); 
     monthsAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 
     monthsSpinner.setAdapter(monthsAdapter); 

     monthsSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() { 
      @Override 
      public void onItemSelected(AdapterView<?> parent, View view, int position, long id) { 
       // показываем позиция нажатого элемента МЕСЯЦ 
       // Toast.makeText(getBaseContext(), "Position = " + position, 
       // Toast.LENGTH_SHORT).show(); 

      } 

      @Override 
      public void onNothingSelected(AdapterView<?> arg0) { 
      } 
     }); 

     Spinner yearSpinner = (Spinner) v.findViewById(R.id.yearSpinner); 
     yearSpinner.setBackgroundColor(0xffF44336); 
     ArrayAdapter<String> yearAdapter = new ArrayAdapter<>(getActivity(), 
       R.layout.my_spinner_gravity_center, years); 
     yearAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 
     yearSpinner.setAdapter(yearAdapter); 

     yearSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() { 
      @Override 
      public void onItemSelected(AdapterView<?> parent, View view, int position, long id) { 
       // показываем позиция нажатого элемента МЕСЯЦ 
       // Toast.makeText(getBaseContext(), "Position = " + position, 
       // Toast.LENGTH_SHORT).show(); 

      } 

      @Override 
      public void onNothingSelected(AdapterView<?> arg0) { 
      } 
     }); 

     return v; 
    } 

    @Override 
    public void onResume() { 
     super.onResume(); 
     getActivity().getSupportLoaderManager().getLoader(0).forceLoad(); 
    } 

    public void onDestroy() { 
     super.onDestroy(); 
     db.close(); 
    } 

    public static MonthFragment newInstance() { 

     return new MonthFragment(); 
    } 

    @Override 
    public Loader<Cursor> onCreateLoader(int id, Bundle bndl) { 
     return new MyCursorLoader(getActivity(), db); 
    } 

    @Override 
    public void onLoadFinished(Loader<Cursor> loader, Cursor data) { 
     scAdapter.swapCursor(data); 
    } 

    @Override 
    public void onLoaderReset(Loader<Cursor> loader) { 
    } 

    static class MyCursorLoader extends CursorLoader { 

     DBAdapter db; 

     public MyCursorLoader(Context context, DBAdapter db) { 
      super(context); 
      this.db = db; 
     } 

     @Override 
     public Cursor loadInBackground() { 
      return db.getMonthRows(); 
     } 

    } 

    public void onCreateContextMenu(ContextMenu menu, View v, 
      ContextMenu.ContextMenuInfo menuInfo) { 
     super.onCreateContextMenu(menu, v, menuInfo); 
     menu.add(0, CM_DELETE_ID, 0, R.string.delete_record); 
    } 

    public boolean onContextItemSelected(MenuItem item) { 
     if (item.getItemId() == CM_DELETE_ID) { 
      // получаем из пункта контекстного меню данные по пункту списка 
      AdapterView.AdapterContextMenuInfo acmi = (AdapterView.AdapterContextMenuInfo) item 
        .getMenuInfo(); 
      // извлекаем id записи и удаляем соответствующую запись в БД 
      db.deleteRow(acmi.id); 
      // получаем новый курсор с данными 
      getActivity().getSupportLoaderManager().getLoader(0).forceLoad(); 
      scAdapter.notifyDataSetChanged(); 
      return true; 
     } 
     return super.onContextItemSelected(item); 
    } 
} 

的

Answer 1

我認爲問題與數組，因爲你不能從數組中刪除元素。 我建議您嘗試ArrayList，並從適配器或數據庫中刪除它時從列表中刪除該元素，然後致電adapter.notifyDataSetChanged();