从SQLite DB创建ArrayList非常慢

Question

Alright, so I'm trying to create a little and lightweight ArrayList from my SQLite DB.

Here's the code:

public ArrayList<Album> getAlbums()
{
    Cursor cursor = null;
    Cursor cursor2 = null;
    try{
        Log.d(Global.TAG, "STARTING");
        ArrayList<Album> albums = new ArrayList<Album>();
        Album album = new Album();
        db = getOpenDatabase(DBADS);
        String albumQuery = "SELECT * FROM " +albumsTableName + " ORDER BY " +albumIsMain + " DESC"; 
        cursor = db.rawQuery(albumQuery, null);
        if (cursor.moveToFirst()){
            do {
                Log.d(Global.TAG, "IN LOOP");
                album = new Album();
                album.id = cursor.getInt(0);
                album.albumName = cursor.getString(1);
                album.passcode = cursor.getString(2);
                album.isMainAlbum = cursor.getInt(3) == 1 ? true : false;
                albumQuery = "SELECT COUNT(*) FROM " + picturesTableName+" WHERE "+ pictureAlbumId +"="+album.id;
                cursor2 = db.rawQuery(albumQuery, null);
                cursor2.moveToFirst();
                album.photosCount = cursor2.getInt(0);
                cursor2.close();

                albums.add(album);
            }
            while (cursor.moveToNext());
        }
        Log.d(Global.TAG, "RETURNING");
        return albums;
    }
    catch(Exception ex)
    {
        Toast.makeText(context, ex.toString(), Toast.LENGTH_LONG).show();
    }
    finally
    {
        if(cursor != null){
            cursor.close();
        }
        if(cursor2 != null){
            cursor2.close();
        }
        if(cursor3 != null){
            cursor3.close();
        }
    }
    return null;

}

The following code executes in like 8 seconds for only 6 items total! This is just exteremly slow.
There are not like 1000 rows here, but only 6. After some debugging, I see that if I remove the other second inner cursor, it becomes very fast.

What could be the reason for that?

Thanks alot.

Answer 1

Save the result of first select statement in a list. Then pass them simultaneously to second select call. Rightnow you are making a lot of db calls