Question

This is a two-part question:

First, I am interested to know what the best way to remove repeating elements from a collection is. The way I have been doing it up until now is to simply convert the collection into a set. I know sets cannot have repeating elements so it just handles it for me.

Is this an efficient solution? Would it be better/more idiomatic/faster to loop and remove repeats? Does it matter?

My second (related) question is: What is the best way to convert an array to a Set? Assuming an array arr The way I have been doing it is the following:


Set x = new HashSet(Arrays.asList(arr));


This converts the array into a list, and then into a set. Seems to be kinda roundabout. Is there a better/more idiomatic/more efficient way to do this than the double conversion way?

Thanks!

Answer 1

1. Do you have any information about the collection, like say it is already sorted, or it contains mostly duplicates or mostly unique items? With just an arbitrary collection I think converting it to a Set is fine.

2. Arrays.asList() doesn’t create a brand new list. It actually just returns a List which uses the array as its backing store, so it’s a cheap operation. So your way of making a Set from an array is how I’d do it, too.