How to get index of an item in java.util.Set

Question

I know the differences between Set and List(unique vs. duplications allowed, not ordered/ordered, etc). What I'm looking for is a set that keeps the elements ordered(that's easy), but I also need to be able to recover the index in which an element was inserted. So if I insert four elements, then I want to be able to know the order in which one of them was inserted.

MySet<String> set = MySet<String>(); set.add("one"); set.add("two"); set.add("three"); set.add("four");  int index = set.getIndex("two"); 

So at any given moment I can check if a String was already added, and get the index of the string in the set. Is there anything like this, or I need to implement it myself?

Answer 1

After creating Set just convert it to List and get by index from List:

Set<String> stringsSet = new HashSet<>(); stringsSet.add("string1"); stringsSet.add("string2");  List<String> stringsList = new ArrayList<>(stringsSet); stringsList.get(0); // "string1"; stringsList.get(1); // "string2";