Comparator - int cannot be dereferenced [duplicate]

Question

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 sort being an Integer, it will not compile, saying "int cannot be dereferenced".

What can I do so that this will work and allow me to sort an ArrayList by the score variable?

Here's my code:

public class ScoreComparator implements Comparator<Review> {
    
    @Override
    public int compare(Review o1, Review o2)
    {
       return o1.getScore().compareTo(o2.getScore());
    }
}

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));
    }
}