ArrayList sorting using Comparator for object

Question

I have Model class which contains

int rs;
String name;

I want to get rs > 8

ArrayList contains all data

  Collections.sort(arreyList, new Comparator< Model >() {

        public int compare(Model one, Model other) {

    int a = one.getrs();
    int b = other.getrs();
            if (a > 8) {
                if (a > b)
                    return -1;
                else if (a < b)
                    return 1;
                else
                    return 0;
            }
            return 0;
        }
    });

but i am getting wrong , and I want to add more filter like > , < , or only that then for string also.

Your innermost if/else if/else can be replaced simply by Integer.compare(b, a). — Andy Turner
– Andy Turner, Commented Feb 17, 2016 at 8:39
Also: Comparators should be anti-symmetrical, so that compare(a, b) == -compare(b, a) - this isn't, because you are only considering a > 8, and not b > 8. — Andy Turner
– Andy Turner, Commented Feb 17, 2016 at 8:41
"i want to get rs > 8" Do you mean you want only the elements for which rs > 8? Comparators can't do that - you need to filter the list first. — Andy Turner
– Andy Turner, Commented Feb 17, 2016 at 8:42

Arun Xavier · Accepted Answer · 2016-02-17 09:21:49Z

1

If you are using Java 8.

Use something like this.

 List<Model> completeModels = new ArrayList<>();

        completeModels.add(new Model(5, "Joe"));
        completeModels.add(new Model(3, "John"));
        completeModels.add(new Model(8, "Smith"));
        completeModels.add(new Model(10, "Lary"));

        List<Model> filtered = completeModels.stream().filter(u -> u.rs > 8).collect(Collectors.toList());

This will give you a list of Models with rs>8 .

For more reference google 'java 8 filter examples' or go through Stream Oracle Doc.

EDIT

Otherwise(if you are not using java 8) write a method to get the list filtered. I don't know other ways to do this.

eg:

private List<Model> getFilteredList(List<Model> completeModels) {

    List<Model> filtered = new ArrayList<>();

    for (Model m : completeModels) {
        if (m.rs > 8) {
            filtered.add(m);
        }
    }

    return filtered;
}

edited Feb 17, 2016 at 9:21

answered Feb 17, 2016 at 9:07

Arun Xavier

7718 silver badges49 bronze badges

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

1 Comment

bob Over a year ago

java 8 not supported yet in andorid

Collectives™ on Stack Overflow

ArrayList sorting using Comparator for object

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related