HashMap vs ArrayList performance am I correct

Question

I currently believe that:

• When you need a structure from which you will be retrieving items randomly - use a HashMap
• When you will be ret

Answer 1

I'd disagree slightly. For me it depends more on how I want to retrieve the items. If I want to do so based on something like their order (by index, to be precise) I would tend to use a linear structure like an ArrayList (or even an array). If I need to look up items, I'd use a map structure like the HashMap.

Another complicating factor has to do with insertions and order, as dan pointed out.