如何从数据库以及Android的ListView中删除项目？

Question

Used Arrayadapter to display elements on listview which are stored in a database. Now I want to delete items from both listview as well database. Please help me to solve it.

Answer 1

To delete row from database try using the sample http://codinglookseasy.blogspot.in/2012/08/sqlite-database.html . and after doing the deletion from database delete the item from the arrayadapter and use adapter.notifyDataSetChanged() to delete it from the list view too

Answer 2

Consider using a cursor adapter to bind the list view to your database table. There's an example here : http://thinkandroid.wordpress.com/2010/01/09/simplecursoradapters-and-listviews/

The example uses the deprecated "startManagingCursor", which has been deprecated in favor of the CursorLoader. CursorLoader is nice once you finally get it implemented. You register some listeners and your UI is immediately updated to reflect any changes to the db (without your having to manually add/remove rows in the listview).

Check out What are the benefits of CursorLoaders?

Answer 3

Here is my code:

Cursor c = db.rawQuery("SELECT * FROM BOOKMARKS", null);

ID = c.getColumnIndex("ID");

            audiotime=c.getColumnIndex("BookmarkTime");
            // Check result.
            c.moveToFirst();
            if (c != null) 
            {
                // Loop through all Results
                do 
                {
                    /*String str=c.getString(ID);
                    audiobooks.add(str);*/
                    str=c.getString(audiotime);
                    audiobooks.add(str);
}
                while(c.moveToNext());

                c.close();
                db.close();

                //TODO
                arrayAdapter=new ArrayAdapter<String>(this,  R.layout.row3, R.id.itemr1,audiobooks);
                lv.setAdapter(arrayAdapter);
cursor.close();
        db.close(); //close db resources
}
public void onClick(View v) 
{
if(v.getId()==R.id.Delete)
{

db = openOrCreateDatabase("DB", 0, null);
db.delete("BOOKMARKS", null, null);

int j=lv.getCount();
                Toast.makeText(GetAudioBookmarks.this, " after delete listview count  " +j,Toast.LENGTH_SHORT).show();



}

I could not able to do that because I am adding only bookmark string to the listview. I have pasted my code which will fetch data from DB and add to listview. Now my code will work like if I click on delete will delete all items on DB but listview count will toast as same value as it hold but wont display any data on listview.