Sort ArrayList of objects through one of its instance variables

Question

Helllo,

I have an ArrayList of OBJECTS (teams). They are football teams and I would like to sort them out through their points. Obviously I am fully aware ArrayLists are sorted via the order they are inserted.

But I have a TEAM class that has gamesWon, gamesLost, gamesTied and points based on a match result.

I have everything ready but figured that sorting out an ArrayList through it's points would be a cool feature to make.

I have read the Collections.sort(myArrayList) online, but this sorts based on ONE type of variable, and since I have objects within the ArrayList, I would like to sort this out.

Thank you.

Marco

Bhesh Gurung · Accepted Answer · 2012-11-19 00:57:32Z

3

You should define a Comparator for this.

public class PointsBasedTeamComparator implements Comparator<Team> {
    public int compare(Team t1, Team t2) {
        //return the result of points comparison of t1 and t2
    }
}

And use it as follows

Collections.sort(teams, new PointsBasedTeamComparator());

edited Nov 19, 2012 at 0:57

answered Nov 19, 2012 at 0:46

Bhesh Gurung

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SJuan76 · Accepted Answer · 2012-11-19 00:44:47Z

2

Define a java.util.Comparator<Team> that implements compareTo with the value that you want to check.
Use the sort method that accepts the Comparator<Object>. It will use the compareTo method of your Comparator, and not the one defined in Team (if any).
Enjoy!

answered Nov 19, 2012 at 0:44

SJuan76

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2 Comments

Tom Anderson Over a year ago

I think this calls for Comparator rather than Comparable; being Comparable implies that the objects have a single natural order, whereas a Comparator is just some particular way of sorting them, of which there could be several.

Marco Berrocal Over a year ago

Ok this is a bit confusing as I have never used Comparator, etc but I am going to read a bit more before I do. Thanks a bunch guys!!

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