Question

Need a collection of strings where elements inserted needed to be sorted and also non-duplicate, can be retrieved through index.

• I can use TreeSet which removes duplicates and sorts everything in
  order but cannot retrieve through index. for retrieving through
  index, i can make ArrayList and addAll elements to it, but this
  addAll takes lot of time.

or

• I can use an ArrayList, insert required and then remove duplicates by some other method, then using Collections.sort method to sort elements.

But the thing is, all these take time, is there any straight-way to achieve this, a collection -sorted, non-duplicate, with O(1) random access by index.

Answer 1

There’s a Data Type in the commons collection called SetUniqueList that I believe meetsyour needs perfectly. Check it out:

https://commons.apache.org/proper/commons-collections/apidocs/org/apache/commons/collections4/list/SetUniqueList.html