从列表视图中删除某个项目（使用SQLite）的结果只能从listview.Can't删除它从数据库中删除 [英] deleting an item from listview (using sqlite) results in only removing it from listview.Can't delete it from database

问题描述

当我尝试在列表视图中删除一个项目，从列表视图中删除，但是当我添加一个新的项目或运行应用程序再次的项目仍然.......我无法从数据库中删除。

When I try to delete an item in list view ,it removes it from list view but when I add a new item or run the application again the items is still there.I can't delete it from database.

我用这code：

...
SqlHandler sqlHandler;
ListView myListView;
myAdapter adapter;
ArrayList<myItems> items;
 ...
 myListView = (ListView) findViewById(R.id.myListView);
 sqlHandler = new SqlHandler(this);
 items = getItemsFromDatabase();

adapter = new myAdapter(this, items);
myListView.setAdapter(adapter);
myListView.setOnItemLongClickListener(this);
 ...
public boolean onItemLongClick(AdapterView<?> adapterView, View view,
        int position, long id) {

    final myItems selectedItem = items.get(position);

    if (selectedItem != null) {
        AlertDialog.Builder alt_bld = new AlertDialog.Builder(this);
        alt_bld.setMessage("Do you want to delete this item?")
                .setCancelable(false)
                .setPositiveButton("Yes",
                        new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog,
                                    int id) {

                                sqlHandler=new SqlHandler(getApplicationContext());
                                sqlHandler.deleteRecord(id);
                                items.remove(selectedItem);
                                adapter.notifyDataSetChanged();

有关我使用的数据库：

public class SqlHandler {
    public static final String DATABASE_NAME = "MY_DATABASE";
    public static final String DATABASE_TABLE = "MEM";
    public static final String KEY_ROWID = "_id";

        public static final int DATABASE_VERSION = 1;
            Context context;
            SQLiteDatabase sqlDatabase;
            SqlDbHelper dbHelper;

            public SqlHandler(Context context) {

                 dbHelper = new SqlDbHelper(context, DATABASE_NAME, null,
                   DATABASE_VERSION);
                 sqlDatabase = dbHelper.getWritableDatabase();
                }

    public void executeQuery(String query) {
     try {

      if (sqlDatabase.isOpen()) {
       sqlDatabase.close();
      }

      sqlDatabase = dbHelper.getWritableDatabase();
      sqlDatabase.execSQL(query);

     } catch (Exception e) {

      System.out.println("DATABASE ERROR " + e);
     }

}

        public Cursor selectQuery(String query) {
         Cursor c1 = null;
         try {

          if (sqlDatabase.isOpen()) {
           sqlDatabase.close();

          }
          sqlDatabase = dbHelper.getWritableDatabase();
          c1 = sqlDatabase.rawQuery(query, null);

         } catch (Exception e) {

          System.out.println("DATABASE ERROR " + e);

         }
         return c1;

}
        public SqlHandler open() throws SQLException
        {
            sqlDatabase = dbHelper.getWritableDatabase();
        return this;
        }

        public void Close(){
            dbHelper.close();

        }
        public void  deleteRecord(long rowId){
            try {
             sqlDatabase.delete(DATABASE_TABLE,KEY_ROWID + "="+rowId,null);
            }
            catch (Exception e)
            {
                Log.e("DB ERROR", e.toString());
                e.printStackTrace();
            }
        }

和

public class SqlDbHelper extends SQLiteOpenHelper {
public static final String DATABASE_TABLE = "MEM";



public static final String TAG="DbHandler";

 public static final String KEY_ROWID = "_id";
 ...


 private static final String SCRIPT_CREATE_DATABASE = "create table "
   + DATABASE_TABLE + " (" + KEY_ROWID
   + " integer primary key autoincrement, " + ....);";

 public SqlDbHelper(Context context, String name, CursorFactory factory,
   int version) {
  super(context, name, factory, version);
  // TODO Auto-generated constructor stub

 }

 @Override
 public void onCreate(SQLiteDatabase db) {
  // TODO Auto-generated method stub
  db.execSQL(SCRIPT_CREATE_DATABASE);

 }

 @Override
 public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
  // TODO Auto-generated method stub
     Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
             + newVersion + ", which will destroy all old data");
  db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);
  onCreate(db);
 }

----------更新---------------------

----------UPDATE---------------------

这应该是某物像：

myItems theItems =(myItems)adapterView.getItemAtPosition(button_id);
String _id = theItems.getID();
String delQuery = "DELETE FROM MEM WHERE _id='"+_id+"' ";
sqlHandler.executeQuery(delQuery);

但我与（myItems）问题适配器视图..我不知道如何处理这个问题。

but I have a problem with the (myItems)adapterView.. I am not sure how to handle this.

推荐答案

您的问题是你方法的调用删除，应该是这样的：

the problem you have is the call of your method delete, it should be like this :

public long deleteItem(myItems itemToDelete) {
    try {
             return sqlDatabase.delete(DATABASE_TABLE,COLUMN_ID + " = ?",new String[]{itemToDelete.getID()});
            }
            catch (Exception e)
            {
                Log.e("DB ERROR", e.toString());
                e.printStackTrace();
                return -1;
            }
}

当你preSS的是 按钮的 AlertDialog 确认删除您应该删除数据库中的项目，然后从数据库加载项并通知列表的适配器与新数据刷新：

and when you press the YES Button of AlertDialog to confirm delete you should delete the item from database, and then reload items from database and notify the adapter of your list to refresh it with the new data :

myItems selectedItem = adapter.getItem(position);
long rows = sqlHandler.deleteItem(selectedItem);
if(rows>0) {
    //get new items from database 
    adapter.setItems(getItemsFromDatabase());
    adapter.notifyDataSetChanged();
}

该项目将从数据库中删除，并在的ListView 将与新的数据被刷新

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