Sorting List in Java

Question

I have this class:

public class Job {
    private int priority;
    private String name;

    public int getPriority() { 
        return priority; 
    }

    public void setPriority(int priority) { 
        this.priority = priority; 
    }

    public String getName() {
        return name; 
    }

    public void setName(Stirng name) { 
        this.name= name; 
    }
}

and I created some collection of it in the below variable:

List<Job> _jobs = ...

How can I sort the list by priority? (top of the list would be the highest priority value)

I found some reference in the internet but could not find a similar example.

Errr ... how long did you search? At least on my end, "java sort list property" gives that existing question right there as first link ;-) — GhostCat, May 18 '17 at 12:58

Gerald Mücke · Accepted Answer · 2017-05-18T13:34:01.403

2

Shortes way would be to use the sort method on the list itself, but this requires a mutable list:

list.sort(Comparator.comparingInt(Job::getPriority))

In case you have an immutable list, you may use streams for that:

List<Job> sortedList = list.stream().sorted(Comparator.comparingInt(Job::getPriority)).collect(toList());

In case you're running on a JDK pre 1.8 use the sort method of the Collections class (requires a mutable list):

 Collections.sort(list, new Comparator<Job>() {

        @Override
        public int compare(final Job o1, final Job o2) {

            return o1.getPriority()-o2.getPriority();
        }
    });

edited May 18 '17 at 13:34

answered May 18 '17 at 12:59

Gerald Mücke

10,724
2
50
67

If you use Java 8, please don't use `Collections.sort` but `List.sort` as shown in the first example. – Olivier Grégoire May 18 '17 at 13:01
@OlivierGrégoire Do you mean in all cases? Because `List.sort` doesn't have the option of using natural ordering – Michael May 18 '17 at 13:08
thanks, will try this – yonan2236 May 18 '17 at 13:12
What? Yes it does: `list.sort(Comparator.naturalOrder());`! – Olivier Grégoire May 18 '17 at 13:12
why is that the sort method does not appear when I type _job.sort? – yonan2236 May 18 '17 at 13:31
you probably run on a JDK < 1.8 – Gerald Mücke May 18 '17 at 13:32
:( is there other way around? – yonan2236 May 18 '17 at 13:33
it seems to work but how can make the highest priority be on top of the list? – yonan2236 May 18 '17 at 13:39
just reverse the order in the comparison (o2-o1 instead of o1-o2) – Gerald Mücke May 18 '17 at 13:39
it works! gracias! – yonan2236 May 18 '17 at 13:41

score 0 · Answer 2 · answered May 18 '17 at 12:59

0

You can use a lambda:

    _jobs.sort((a,b) -> Integer.compare(a.getPriority(), b.getPriority()));
    System.out.println(_jobs);

answered May 18 '17 at 12:59

ΦXocę 웃 Пepeúpa ツ

47,427
17
69
97

Sorting List in Java

2 Answers2