Java Sort List of Lists

Question

How would I sort a list of lists in Java in lexicographical order using Collections.sort() or another sorting method?

private List>         


        

Answer 1

You will have to implement your own Comparator class and pass in an instance to Collections.sort()

class ListComparator> implements Comparator> {

  @Override
  public int compare(List o1, List o2) {
    for (int i = 0; i < Math.min(o1.size(), o2.size()); i++) {
      int c = o1.get(i).compareTo(o2.get(i));
      if (c != 0) {
        return c;
      }
    }
    return Integer.compare(o1.size(), o2.size());
  }

}

Then sorting is easy

List> listOfLists = ...;

Collections.sort(listOfLists, new ListComparator<>());