Expandable lists let you create lists within lists.
They’re ideal for list items that have sub-categories. The user selects an item from a scrollable list and another list pops open. They can then make another selection from this list.
Here’s the second part of the Volley tutorial.
This is where we show you how to use Volley to download images and display them in a ListView.
A ListView displays items in a vertical, scrolling list. It contains a number of views, one for each item in the list. Here’s an example: