android - Reading and Writing to a SQLITE3 database from a ListView populated by a CursorAdapter -

i made android app online program part of. app supposed track inventory. app uses cursoradapter populate listview 3 inventory details - productname, product price , quantity. part of assignment add button on each list item when clicked quantity decreased 1 , new value stored in database. problem having each listitem populated cursoradapter, code not in activity. know how read , write database activity not cursoradapter. assuming cursoradapter need put code because place there logic textviews shown in each list item. tried has failed. unfortunately can't show have tried because @ point decided delete , start scratch.

here each list item should like.

here code cursoradapter:

public class inventorycursoradapter extends cursoradapter {  private uri mcurrentinventoryuri;    /**  * constructs new {@link inventorycursoradapter}.  *  * @param context context  * @param c       cursor data.  */ public inventorycursoradapter(context context, cursor c) {     super(context, c, 0 /* flags */); }  /**  * makes new blank list item view. no data set (or bound) views yet.  *  * @param context app context  * @param cursor  cursor data. cursor  *                moved correct position.  * @param parent  parent new view attached  * @return newly created list item view.  */ @override public view newview(context context, cursor cursor, viewgroup parent) {     // inflate list item view using layout specified in list_item.xml     return layoutinflater.from(context).inflate(r.layout.list_item, parent, false); }   @override public void bindview(view view, context context, cursor cursor) {       // find individual views want modify in list item layout     textview nametextview = (textview) view.findviewbyid(r.id.name);     final textview quantitytextview = (textview) view.findviewbyid(r.id.quantity);     textview pricetextview = (textview) view.findviewbyid(r.id.price);        // find columns of product attributes we're interested in     int namecolumnindex = cursor.getcolumnindex(inventoryentry.column_product_name);     int quantitycolumnindex = cursor.getcolumnindex(inventoryentry.column_product_quantity);     int pricecolumnindex = cursor.getcolumnindex(inventoryentry.column_product_price);      // read product attributes cursor current product     string productname = cursor.getstring(namecolumnindex);     //string productname = "productname";     int productquantity = cursor.getint(quantitycolumnindex);     int productprice = cursor.getint(pricecolumnindex);        if (textutils.isempty(productname)) {         productname = context.getstring(r.string.unknown_product);     }       // update textviews attributes current product     nametextview.settext(productname);     quantitytextview.settext(integer.tostring(productquantity));     pricetextview.settext(" $" + integer.tostring(productprice));    } 

}

you can see can use cursor , display data listview, don't know how update quantity, , save database. when tried adding button view binded listview, other touch functionalities had set click on list doesn't work (touching on list item opens detailed screen more product info).

i tried including functionality main activity since button isn't located in activity when called getviewbyid ended being null , app crashed. included enough code snippet, not sure else have been relevant. in addition posted have 2 other activity (main activity , activity edit details of inventory), have database helper files reading , writing database.

to make easier on reading this, there 2 major obstacles facing. 1). place button. using layout called cursoradapter best place? 2). put code update database? using cursoradapter provided challenges me.

thanks in advance..