How can I sort a Java list using two different values?

Question

public void sortLeagueTable(List<LeagueTableItem> table) {
    Collections.sort(table, new Comparator<LeagueTableItem>(){
        public int compare(LeagueTableItem o1, LeagueTableItem o2){
            return o2.getPoints() - o1.getPoints();
        }
    });
}

This code sorts two lists based on the value of the object called points. After I sort it based on the value point I want to sort it again based on the value goalScored. So, if the points of two teams are equal, I want to sort it again based on the goalScored value.

How can I do that?

Possible duplicate of [Using Comparable for multiple dynamic fields of VO in java](https://stackoverflow.com/questions/16206629/using-comparable-for-multiple-dynamic-fields-of-vo-in-java) — SedJ601, Dec 04 '17 at 14:35

Mureinik · Answer 1 · 2017-12-04T14:44:47.603

9

Java 8's enhancements to the Comparator interface give you a pretty elegant way of achieving this:

table.sort(Comparator.comparingInt(LeagueTableItem::getPoints)
                     .thenComparingInt(LeagueTableItem::goalScored));

edited Dec 04 '17 at 14:44

answered Dec 04 '17 at 14:38

Mureinik

297,002
52
306
350

score 2 · Accepted Answer · answered Dec 04 '17 at 14:35

Just add another condition to your comparator:

public int compare(LeagueTableItem o1, LeagueTableItem o2){
     int diff = o2.getPoints() - o1.getPoints();
     if (diff == 0) {
        diff = o2.goalScored() - o1.goalScored();
     }
     return diff;
}

Stiliyan Koev · Answer 3 · 2017-12-07T14:24:31.403

1

public int compare(LeagueTableItem o1, LeagueTableItem o2) {
        if (o2.getPoints() == o1.getPoints()) {

            return o2.goalsScored() - o1.goalsScored();
        } else {
            return o2.getPoints() - o1.getPoints();
        }
    }

First it gets the o1 and o2's points and compare them. If they are equal, the if statement proceed to calculate which o has more goals scored and returns the result, else if the points are NOT equal it returns the result.

edited Dec 07 '17 at 14:24

answered Dec 04 '17 at 14:37

Stiliyan Koev

61
12

Thank you for this code snippet, which might provide some limited, immediate help. A proper explanation [would greatly improve](//meta.stackexchange.com/q/114762) its long-term value by showing *why* this is a good solution to the problem, and would make it more useful to future readers with other, similar questions. Please [edit] your answer to add some explanation, including the assumptions you've made. – Toby Speight Dec 04 '17 at 15:03

How can I sort a Java list using two different values?

3 Answers3