Question

I have a two dimensional ArrayList that I need to filter the duplicates out of.

current result of generateRows: [[“one”], [“two”], [“three”], [“one”]]

Java Pseudo Code:

ArrayList<ArrayList<String>> rows = new ArrayList<ArrayList<String>>();
rows = generateRows(); //method not shown, but returns a ArrayList<ArrayList<String>>
Set<String> set = new LinkedHashSet<String>();
for (ArrayList<String> list:rows) {
    set.addAll (list);
}
rows.clear();
rows.add(new ArrayList<String>(set));

current result after running above conversion code: [[one, two, three]]

desired result: [[“one”], [“two”], [“three”]]

Answer 1

Keeping code in same lines as what you have posted, here is what you have to do.

ArrayList<ArrayList<String>> rows = new ArrayList<ArrayList<String>>();
rows = generateRows(); //method not shown, but returns a ArrayList<ArrayList<String>>
Set<ArrayList<String>> set = new LinkedHashSet<ArrayList<String>>();
set.addAll(rows);
rows.clear();
rows.addAll(set);

Main issue with your routine:

Set<String> set = new LinkedHashSet<String>(); you are saying set is going to contain String types while your real set of objects to be unique is of ArrayList type