This week's book giveaway is in the General Computing forum. We're giving away four copies of Arduino in Action and have Martin Evans, Joshua Noble, and Jordan Hochenbaum on-line! See this thread for details.
Ordered : when a collection is ordered it means you can iterate through the collection in a specific order. An ArrayList is ordered by index.
Sorted : when a collection contains objects that are organized according to some rules. A TreeSet is a sorted collection because its elements are organized in ascending order(it has nothing to do with what position it was added at)