How are holders in custom listView created?

Question

I saw a program for the custom listview in the following link http://www.ezzylearning.com/tutorial.aspx?tid=1763429&q=customizing-android-listview-items-with-custom-arra

Answer 1

during the scrolling of ListView findViewById() (which layout's children is inflated for a row of listview) is called frequently, which can slow down performance. Even when the Adapter returns an inflated view for recycling, you still need to look up the elements and update them. A way around repeated use of findViewById() is to use the view holder design pattern.

A ViewHolder object stores each of the component views inside the tag field of the Layout, so you can immediately access them without the need to look them up repeatedly. First, you need to create a class to hold your exact set of views.

Here is the class in your code

static class WeatherHolder {
        ImageView imgIcon;
        TextView txtTitle;
}

Yes it is manually created by us in getView() u will create Object of that class and access it

 @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View row = convertView;
        WeatherHolder holder = null;

        if(row == null)
        {
            LayoutInflater inflater = ((Activity)context).getLayoutInflater();
            row = inflater.inflate(layoutResourceId, parent, false);

            holder = new WeatherHolder();
            holder.imgIcon = (ImageView)row.findViewById(R.id.imgIcon);
            holder.txtTitle = (TextView)row.findViewById(R.id.txtTitle);

            row.setTag(holder);
        }
        else
        {
            holder = (WeatherHolder)row.getTag();
        }
//do ur staff
return row;
}

For more info Visit here

http://developer.android.com/training/improving-layouts/smooth-scrolling.html