Question

I have an arrayList of arrayLists. Each inner arraylist contains some objects with the format (name.version) .

{  {a.1,b.2,c.3} , {a.2,d.1,e.1} , {b.3,f.1,z.1}....} 

For example a.1 implies name = a and version is 1.

So i want to eliminate duplicates in this arraylist of lists. For me , two objects are duplicate when they have the same name

So essentially my output should be

{ { a.1,b.2,c.3},{d.1,e.1} ,{f.1 ,z.1} }

Note that i want the output in the exact same form (That is , i dont want a single list with no duplicates)

Can someone provide me with an optimal solution for this?

I can loop through each inner list and place the contents in the hashset. But two issues there, i cant get back the answer in
form of list of lists.Another issue is that when i need to override equals for that object , but i am not sure if that would
break other code. These objects are meaningfully equal if their names are same (only in this case. I am not sure that would
cover the entire spectrum)

Thanks

Answer 1

List<List<Pair>> inputs; // in whatever format you have them
List<List<Pair>> uniqued = new ArrayList<>(); // output to here
Set<String> seen = new HashSet<String>();
for (List<Pair> list : inputs) {
  List<Pair> output = new ArrayList<>();
  for (Pair p : list)
    if (seen.add(p.getName()))
      output.add(p);
  uniqued.add(output);
}