Empty SQLite Database after row inserting

I want to store data into an SQLite database on Android with this method:

public void addMedicine(Medicine medicine)
{
    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues values = new ContentValues();

    values.put(COLUMN_NAME, medicine.get_name());
    values.put(COLUMN_FORMAT, medicine.get_format());
    values.put(COLUMN_AMOUNT, medicine.get_amount());
    values.put(COLUMN_EXP_DATE, medicine.get_exp_date());
    values.put(COLUMN_TIME, medicine.get_time());

    db.insert(TABLE_MEDICINES, null, values);

    db.close();
}

The Medicine object i pass to the addMedicine method is an instance of a class i created, and it works.

When i want to select data from the TABLE_MEDICINES i use this function:

public int getMedicines()
{
    String med = "";
    SQLiteDatabase db = getWritableDatabase();
    String SELECT_MEDICINES = "SELECT * FROM " + TABLE_MEDICINES;

    // Setting cursor to the first row.

    Cursor cursor = db.rawQuery(SELECT_MEDICINES, null);
    cursor.moveToFirst();

    int tmp_count = 0;

    while(!cursor.isAfterLast())
    {
        if(cursor.getString(cursor.getColumnIndex("name")) != null)
        {
            med += cursor.getString(cursor.getColumnIndex("name"));
            med += "\n";
            tmp_count++;
        }
    }

    db.close();

    return tmp_count;

}

I only count how many rows are in the table and set the text of a TextView with the tmp_count value. When i run the app, the TextView is always 0, and i think the database is empty so the row hasn't been inserted. Anyone as any idea? Thank you all in advance!