why does the ViewHolder pattern work?

Question

I learned Android\'s ArrayAdapter today, and find there is a commom pattern which uses a ViewHolder to hold Views\' reference instead of calling findViewById everytime.

Answer 1

Sorry but denis' answer may be wrong. In fact, the view instances(and ViewHolders) are as many as your screen can display.

If your screen looks like:

[list view]
the first item
the second item
the third item
the fourth item

You will have 4 instances of views. If you scroll screen, the first will disappear but be pass to getItem() as convertView for you to create the fifth item.

So you can use the references in first ViewHolder.