On Button Click how to increment counter and show in textview

Question

I am working on a shopping cart assignment for that I have created a custom ListView that contains the Picture, Price and Add to Cart button in each row. I also have a textview

Answer 1

Make sure you have reference to your TextView in xml.

Connect it (using findViewById()) inside onCreate() of Activity only, and you may pass it to your Adapter (i.e making a class field and setter getter method), if Adapter is a separate class.

and dont do this inside getView() of Adapter, remove this line.

final TextView tv  = (TextView)convertView.findViewById(R.id.tvCount);

you will pass your TextView from Activity to Adapter using constructor or setter getter method, will keep a reference using class Adapter's class level variable and the what you will do inside onClick() of Button is:

btn.setOnClickListener(new View.OnClickListener() {
     @Override
     public void onClick(View v) {
          count++;
         yourClassLevelTextView.setText(String.valueOf(count));
     }});

EDIT:

how you will pass TextView to Adapter

public class YourAdapter extends BlahBlahBlah
{
     private TextView yourClassLevelTextView;
     public void setTextView(TextView textViewFromActivity)
     {
         this.yourClassLevelTextView = textViewFromActivity;
     }
}

and in Activity do something like this:

YourAdapter adapter = new YourAdapter(blah, blah, blah);
adapter.setTextView(yourTextViewInActivity);
listView.setAdapter(adapter);