如果数量增加或减少，总体效果如何？

Question

I want if i increase the qty then total should also effect and when decrease the quantity,from the total also should subtract.on increase and decrease qty amount working perfect but there is a issue in total,How can i do this,Please help if someone have idea?

     holder.inc.setOnClickListener( new View.OnClickListener(){// this method is for increase the quantity by the cart_id
                        @Override
                        public void onClick(View view) {

                            float amount=0,Amt_with_cgst_sgst=0,qty_return=0;;
                            float gst= Float.parseFloat( holder.txt_gst.getText().toString() );
                            bill_id= Integer.parseInt( holder.txt_bill_id.getText().toString() );
                            Cat_id= Integer.parseInt( holder.txt_cart_id.getText().toString() );
                            float qty= Float.parseFloat( holder.txt_per_qty.getText().toString());
                            float price = Float.parseFloat( holder.txt_price.getText().toString() );
                            float inc_qty= Float.parseFloat( holder.inc_quantity.getText().toString());
                            float CGST=  Float.parseFloat(holder.txt_cgst.getText().toString());
                            float SGST= Float.parseFloat( holder.txt_sgst.getText().toString());
                           if(inc_qty<billlist.get(i).getC_qunanity()){ //it will increase the value  till that value  exit before the change only
                                inc_qty++;
                                holder.inc_quantity.setText(String.valueOf(inc_qty));
                             }
                            float sales_qty= billlist.get( i).getC_qunanity();
                            qty_return = sales_qty+inc_qty;
                            amount =(price/qty)*inc_qty;
                            float sales_amt= billlist.get(i).getC_Amount();
                            float amt_return = sales_amt+amount;
                            Float cgst_sgst =amount*(CGST+SGST)/100;
                            Amt_with_cgst_sgst= amount+cgst_sgst;
                            holder.txt_amount.setText(String.valueOf(Amt_with_cgst_sgst));

                            Add_Sales.txt_grand_total.setText( String.valueOf(getTotal_Add( Amt_with_cgst_sgst )));//getTotal is a method for calculating the total

                            holder.desc.setOnClickListener( new View.OnClickListener() {//this method is for decrease the quantity by the cart_id
                            @Override
                            public void onClick(View view){
                                float gst= Float.parseFloat( holder.txt_gst.getText().toString() );

                            bill_id = Integer.parseInt( holder.txt_bill_id.getText().toString() );
                            Cat_id = Integer.parseInt( holder.txt_cart_id.getText().toString() );

                            float qty = Float.parseFloat( holder.txt_per_qty.getText().toString());
                            float price = Float.parseFloat( holder.txt_price.getText().toString() );
                          //  float Amt= Float.parseFloat( holder.txt_amount.getText().toString());
                            float inc_qty= Float.parseFloat( holder.inc_quantity.getText().toString());
                            float CGST =  Float.parseFloat(holder.txt_cgst.getText().toString());
                            float SGST = Float.parseFloat( holder.txt_sgst.getText().toString());
                            float qty_return=0;
                            if(inc_qty>0){
                                inc_qty--;
                                holder.inc_quantity.setText(String.valueOf(inc_qty));
                                float sales_qty= billlist.get(i).getC_qunanity();
                                qty_return  = sales_qty-inc_qty;
                              }
                            float amount =(price/qty)*inc_qty;//calculating the amount by price or qty without gst
                            float sales_amt = billlist.get(i).getC_Amount();
                            float amt_return = sales_amt-amount;
                            Float cgst_sgst = amount*(CGST+SGST)/100;

//calculating amount with gst float Amt_with_cgst_sgst= amount+cgst_sgst; holder.txt_amount.setText(String.valueOf(Amt_with_cgst_sgst));//setting the amount after doing calculation

                           Add_Sales.txt_grand_total.setText( String.valueOf(getTotal_Sub(Amt_with_cgst_sgst )));

    public float getTotal_Add(float price){ //calculating the total amount here
            for(int i=0;i<billlist.size();i++){
                price+=billlist.get( i ).getC_Amount();//getting the amount by the position wise
            }
            return price;
        }

Answer 1

Yes you can use mutable live data for the quantity and billing amount you have to take 2 mutable live data variable, and observe quntity live data when you change value it reflect in obesrver and than do process on update value and again push the value in price data

var qua=Mutablelivedata() var price=MutableLivedate()

qua.observe(ths(@lifecyle may be activity or fragment),Observe{ //here you can get updated qua value

 price.value=value after opration

})

use data two data binding so reflect

Answer 2

when ever user click - or + icons call this method

private void updateProductPrice(int quantity){
    itemPrice=(quantity*itemCostPrice);
    tv_Price.setText("$"+itemPrice);
}