android how to collections.sort the object?

Question

Now I have 3object

user[0] = new user("a", "a");
user[1] = new user("b", "b");
user[2] = new user("c", "c");

there have many variable in the object such as: age, name, email

then the program is running.....

user[0].setAge(6);
user[1].setAge(5);
user[2].setAge(7);

how can I get the young to old user name?

the exception return: b,a,c

Create comparator which will use result of `getAge` and pass it to `Collections.sort` along with your collection of `user`. — Pshemo, Apr 14 '15 at 19:31
Use standard naming conventions, and certainly never create a variable with the same name as a class! — Paul Boddington, Apr 14 '15 at 19:37

score 1 · Accepted Answer · edited Apr 14 '15 at 20:11

You can either make User Comparable and have it's natural ordering by age:

public class User implements Comparable<User> {
    // snipped...

    @Override
    public int compareTo (User other) {
        return Integer.compare(age, other.age);
    }
}

Or explicitly specify a Comparator when you're sorting:

Collections.sort(users, new Comparator<User>() {
    @Override
    public int compare(User a, User b) {
        return Integer.compare(a.getAge(), b.getAge());
    }
});

android how to collections.sort the object?

1 Answers1