How can i sort my Arraylist?

Question

I have this user class

public class User {

public String userName;
public int highScore = 0;

public static ArrayList<User> userList = new ArrayList<User>(5);

public User(String name, int score) {
    this.userName = name;
    this.highScore = score;
    userList.add(this);

    Collections.sort(userList, new Comparator<User>() {
        @Override
        public int compare(User lhs, User rhs) {
            return lhs.highScore-rhs.highScore;
        }

    });

}

}

The User object has properties name and score.i want to sort my list on the basis of score of the user.

Please tag your questions with the appropriate language. – user229044 Feb 22 '13 at 14:52 — user229044, Feb 22 '13 at 14:52

Taky · Accepted Answer · 2013-02-22T18:23:18.063

3

    java.util.Collections.sort(userList, new Comparator<User>(){
        @Override
        public int compare(User lhs, User rhs) {
            return lhs.getScore() - rhs.getScore();
        }

    });

edited Feb 22 '13 at 18:23

answered Feb 22 '13 at 14:58

Taky

5,284
1
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@user2015770 what is not work for you? – Taky Feb 22 '13 at 18:23

mjshaw · Answer 2 · 2013-02-22T15:40:24.580

0

Create an object that implements Comparator:

http://docs.oracle.com/javase/6/docs/api/java/util/Comparator.html

This essentially implements a comparison between two objects. From this, you can use automatic sort methods.

public class UserComparator implements Comparator {
    public boolean compare(Object object1, Object object2) {
        return ... \\ result of comparison
    }
}
public static ArrayList<User> userList = new ArrayList<User>(5);

Collections.sort(usersList, new UserComparator());

the return value is an int.

0 if object1 equals object2
a negative int if object1 < object2
a positive int if object1 > object2

edited Feb 22 '13 at 15:40

answered Feb 22 '13 at 14:58

mjshaw

401
2
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what should be the result? – Mukul Feb 22 '13 at 15:34
The result is 0 if object1 equals object2, a negative int if object1 is less than object2, a positive int if object1 is more than object2. – mjshaw Feb 22 '13 at 15:38
not working.tried returning lhs.highScore-rhs.highScore – Mukul Feb 22 '13 at 16:31
Give more details. Will it not compile? Does it fail at run time? Or does it simply not sort them? – mjshaw Feb 22 '13 at 16:35
it is compiling but not sorting. – Mukul Feb 22 '13 at 16:45
Is it: not changing values at all; or changing them, but not as expected? – mjshaw Feb 22 '13 at 16:57

How can i sort my Arraylist?

2 Answers2