Question

I am writing my own comparator class called PercentComparator and called the sort as follows

Collections.sort(engineList, new PercentageComparator());

where engineList is List of objects, where each object has percent complete values, and above sort functionality is working fine.

Now customer is asking to add another order by element by its product type along with percent. Can we do sort order by two elements of objects?

Answer 1

If I got it right:

class EngineComparator implements Comparator<Engine> {
    @Override
    public int compare(Engine o1, Engine o2) {
        int result = o1.getProdType().compareTo(o2.getProdType());
        return (result == 0) ? o1.getPercent().compareTo(o2.getPercent()) : result;
    }
}

Following is how it sorts the collection:

Prod-Type   Percent
=======================
  A         1
  A         2
  A         3
  B         1
  B         2
  B         3
  C         1
  C         2
  C         3