Sort an ArrayList by subclasses in Java

Question

so I am trying to sort an ArrayList as the title says. I have A Superclass called Thing that has 2 different subclasses, a HeavyThing and a LightThing. The ArrayList contains just the 2 subclasses and I need to sort it so the HeavyThing comes before the LightThing. So far I got the sort method to work for the name of the Things but I was unable to sort it by subclass.

        this.collThings.sort(new Comparator<Thing>() {
            public int compare(Thing t1, Thing t2) {
                return Integer.valueOf(t1.getName().compareTo(t2.getName()));
            }
        });

This is how I sorted it by name.

Karol Dowbecki · Accepted Answer · 2020-11-16 17:22:56Z

2

You can create a comparator chain and then as a first step compare the class' simple name. This will put HeavyThing before LightThing because in lexicographic order H comes before L. Then you can sub-sort by name:

this.collThings
    .sort(Comparator.comparing(t -> t.getClass().getSimpleName())
                    .thenComparing(Thing::getName));

answered Nov 16, 2020 at 17:22

Karol Dowbecki

45.3k9 gold badges83 silver badges118 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

b.tchman Over a year ago

Thank you this very useful, but I later down the line I have to sort the things by Date, Price etc. and I need to Sort the ArrayList just by telling if it is a heavy or a light thing.

Collectives™ on Stack Overflow

Sort an ArrayList by subclasses in Java

1 Answer 1

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related