Comparator - int cannot be dereferenced

Question

So I saw an example on here how to sort an ArrayList using the Comparator interface, so I tried it out. With Strings it worked perfectly, but with one variable that I want to so

Answer 1

Fyi, although this doesn't answer your specific question about the int dereferencing error, in Java 8 you don't need the dedicated comparator class at all. You can simply write:

yourList.sort((r1, r2) -> Integer.compare(r1.getScore(), r2.getScore()));

or

yourList.sort(Comparator.comparingInt(Review::getScore));

both of which are much nicer ways to do it.

Answer 2

try this:

public class ScoreComparator implements Comparator<Review> {

    @Override
    public int compare(Review o1, Review o2)
    {
         return (o1.getScore()<o2.getScore() ? -1 : (o1.getScore()==o2.getScore() ? 0 : 1));
    }
}

Answer 3

You can't call methods on ints; there's no compareTo method to call. That would be on the boxed Integer type, but boxing would be overkill.

If you're on Java 7+, you should write

return Integer.compare(o1.getScore(), o2.getScore());

...otherwise you'll more or less need to write

if (o1.getScore() < o2.getScore()) {
   return -1;
} else if (o1.getScore() > o2.getScore()) {
   return 1;
} else {
   return 0;
}