如何从android中的自定义列表视图中获取所选项目数

Question

如何从自定义列表视图中获取所选项目数。

viewHolder.imgbtnp.setOnClickListener(new View.OnClickListener() {
                Product pp = productdata.get(position);
                @Override
                public void onClick(View v) {
                    if (pp.getUserQty() < 10)
                        pp.setUserQty(pp.getUserQty() + 1);
                    productdata.set(position, pp);
             viewHolder.tv_qty.setText(String.valueOf(pp.getUserQty()));
                    ProductAdapter.this.notifyDataSetChanged();
                }
            });

            viewHolder.imgbtnm.setOnClickListener(new View.OnClickListener() {
                Product pp = productdata.get(position);
                @Override
                public void onClick(View v) {
                    // TODO Auto-generated method stub
                    if (pp.getUserQty() > 0)
                        pp.setUserQty(pp.getUserQty() - 1);
                    productdata.set(position, pp);                            viewHolder.tv_qty.setText(String.valueOf(pp.getUserQty()));
                    ProductAdapter.this.notifyDataSetChanged();
                }
            });

                  int totalCartValue = 0;
                    if (productdata != null && productdata.size() > 0) {
                        for (int i = 0; i < productdata.size(); i++) {
                            Product hi = productdata.get(i);
                  totalCartValue = totalCartValue +                            hi.getProductValue();
                        }
                           viewHolder.tv_value.setText("" + totalCartValue);
                       Log.d(Config.tag, "total cart size" +    totalCartValue);
                    }