Question

There is one simple question which after searching i wanted to ask that why we create static holder class and assign the views inside it?? Please clear my doubts it will be great help to me.

Answer 1

Your code might call findViewById() frequently during the scrolling of ListView, 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.

You can read Android Guideline for more detail.

1. So when you are using “View Holder” then you can easily access each view without the need for the look-up which saving valuable processor cycles.
2. having a static inner class for the views greatly improves performance

you can also see Why does Android prefer static classes link.

One more interesting link How ListView Work, after reading this blog developer can clear logic of LisView and also why need to implement inner static class for listView.