array of structures, or structure of arrays?

Question

Hmmm. I have a table which is an array of structures I need to store in Java. The naive don\'t-worry-about-memory approach says do this:

public class Record          


        

Answer 1

The second version is much, much worse. Instead of resizing one array, you're resizing three arrays when you do an insert or delete. What's more, the second version will lead to the creation of many more temporary objects and it will do so on accesses. That could lead to a lot of garbage (from a GC point of view). Not good.

Generally speaking, you should worry about how you use the objects long before you think about performance. So you have a record with three fields or three arrays. Which one more accurately depicts what you're modeling? By this I mean, when you insert or delete an item, are you doing one of the three arrays or all three as a block?

I suspect it's the latter in which case the former makes far more sense.

If you're really concerned about insertion/deletion performance then perhaps a different data structure is appropriate, perhaps a SortedSet or a Map or SortedMap.