ListView with Custom NumberPickers - Incremented number not being displayed

ListView with Custom NumberPickers - Incremented number not being displayed

I am currently working on an Activity which requires a ListView with
custom NumberPickers. I created the number picker as suggested here.
The problem which I am facing is quite frustrating; when I click on the +
button of the number picker, the text view keeps displaying 0. I have
tried all these suggestions but nothing has been changed.
@Override
public View getView(int position, View convertView, ViewGroup parent)
{
View vi = convertView;
//ViewHolder holder = new ViewHolder();
if(vi == null)
{
holder = new ViewHolder();
vi = inflater.inflate(R.layout.materialdialogcontent, null);
//Initialize Buttons and TextViews.
holder.num.setText("0");
holder.add.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
counter++;
holder.num.setText("" + counter);
}
});
holder.sub.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
counter--;
holder.sub.setText("" + counter);
}
});
//holder.pk = (NumberPicker)vi.findViewById(R.id.npMaterialAmount);
vi.setTag(holder);
}
else
{
holder = (ViewHolder)vi.getTag();
}
holder.txt.setText(data.get(position).getName());
//holder.pk.setMaxValue(20);
//holder.pk.setMinValue(0);
return vi;
}
public static class ViewHolder
{
TextView txt;
Button add;
Button sub;
TextView num;
//NumberPicker pk;
}
The above code is found in my ListView Adapter.
The following is what I have already tried:
When I debug the above code, the counter increments, and the debugger
variable shows that the TextView's text is actually being set to the
number present in the counter, however the number displayed is still 0.
I have also tried setting an OnItemClickListener() to the ListView, and
nothing happens still. I then removed the Button click listeners from the
ListView Adapter class and placed them inside the ListView's
onItemClickListener(). When debugging however, the Button click listeners
are skipped by the debugger.
Do you have any other suggestions?
I would gratefully appreciate all help possible.