How to sort Arraylist of objects

Question

I have ArrayList, which containst football teams (class Team). Teams have points and i want to sort them by number of points.

 public class Team {
     priva         


        

Answer 1

It is not actually necessary to define a custom Comparator like this.

Instead, you can easily define one, when you want to sort your ArrayList.

Since JAVA 8 using lamda

    // Sort version.
    Iteams.sort(Comparator.comparing(Team::getPoints));

    // Complete version.
    Iteams.sort((o1, o2) -> o1.getPoints().compareTo(o2.getPoints()));

Also there are options for second comparator, if objects are equals on the first:

    // e.g. if same points, then compare their names.
    Iteams.sort(Comparator.comparing(Team::getPoints).thenComparing(Team::getName));

Also note that the default sort option is ascending, but you can set it to descending using:

    // e.g. Sort by points descending.
    Iteams.sort(Comparator.comparing(Team::getPoints).reversed());

That way, you can sort your ArrayList in different ways whenever you want, just by adding the method you want.