Merging two arrayLists into a new arrayList, with no duplicates and in order, in Java

Question

I am trying to \"combine\" two arrayLists, producing a new arrayList that contains all the numbers in the two combined arrayLists, but without any duplicate elements and the

Answer 1

Instead of the code you wrote, you may use ArrayList.addAll() to merge the lists, Collections.sort() to sort it and finally traverse of the resulting ArrayList to remove duplicates. The aggregate complexity is thus O(n)+O(n*log(n))+O(n) which is equivalent to O(n*log(n)).

Answer 2

List<String> listA = new ArrayList<String>();

    listA.add("A");
    listA.add("B");

List<String> listB = new ArrayList<String>();

    listB.add("B");
    listB.add("C");

Set<String> newSet = new HashSet<String>(listA);

    newSet.addAll(listB);
List<String> newList = new ArrayList<String>(newSet);

System.out.println("New List :"+newList);

is giving you New List :[A, B, C]