Sort LinkedList in Java

Question

I have a List:

 LinkedList<Student> student = new LinkedList<Student>();

In the Student class, it has an attribute String name. I want to sort the List students by its name. Is there any way I could do that?

Make it implement Comparable or pass a comparable to the sort function — Thiyagu, Aug 07 '18 at 04:57
I think you could look at this one: [here](https://stackoverflow.com/a/33190240/7616247) — Andy, Aug 07 '18 at 04:58
Hello Ryan, Welcome to StackOverflow, As the commentators suggested, you can search the existing questions which were already answered. If you still think your case is unique, provide more details. — srikanth Nutigattu, Aug 07 '18 at 05:02

score 3 · Answer 1 · answered Aug 07 '18 at 05:20

3

student.sort(Comparator.comparing(Student::getName));

Read more about comparators.

answered Aug 07 '18 at 05:20

Kartik

7,677
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50

score 1 · Answer 2 · answered Aug 07 '18 at 05:00

1

You can define a Comparator to do this. One easy way is with an anonymous class. https://docs.oracle.com/javase/8/docs/api/java/util/Comparator.html

Collections.sort(student, new Comparator<Student>() {
    public int compare(Student a, Student b) {
        return a.getName().compare(b.getName());
    }
};

answered Aug 07 '18 at 05:00

Oxy

71
6

If you're quoting Java 8, use a lambda. – chrylis -cautiouslyoptimistic- Aug 07 '18 at 05:44

score 0 · Answer 3 · answered Aug 07 '18 at 05:10

You can use the Collections.sort method accepts a comparator as its second argument. Pass in a comparator that defines the ordering that you would like. For example given a Student class, you can use Collections.sort with a custom comparator to sort Student by ascending order of name like this:

import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedList;
import java.util.List;

class Student {

    private final String name;
    private final int score;

    Student(String name, int score) {
        this.name = name;
        this.score = score;
    }

    public String getName() {
        return name;
    }

    public int getScore() {
        return score;
    }

    @Override
    public String toString() {
        return "Student [name=" + name + ", score=" + score + "]";
    }

    public static void main(String[] args) {
        List<Student> list = new LinkedList<>(
                Arrays.asList(new Student("David", 3), new Student("Alice", 3), new Student("Thomas", 9)));

        System.out.println("Before Sort: " + list);

        Collections.sort(list, new Comparator<Student>() {
            @Override
            public int compare(Student o1, Student o2) {
                return o1.getName().compareTo(o2.getName());
            }
        });

        System.out.println("After Sort: " + list);
    }

}

This will produce the output

before: [Student [name=David, score=3], Student [name=Alice, score=3], Student [name=Thomas, score=9]]
after: [Student [name=Alice, score=3], Student [name=David, score=3], Student [name=Thomas, score=9]]

score 0 · Answer 4 · answered Aug 07 '18 at 05:18

0

if you use java > 8. You can use Lambda expression, and you get something like this:

Collections.sort(student, (p1, p2) -> p1.name.compareTo(p2.name));

or Using sort method in List

student.sort((p1, p2) -> p1.name.compareTo(p2.name));

answered Aug 07 '18 at 05:18

Pascal Fares

21,959
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score 0 · Accepted Answer · answered Aug 07 '18 at 05:25

simply you can use this

   student.sort(Comparator.comparing(Student:: getName));//Single Sorting
    student.sort(Comparator.comparing(Student:: getName).reversed());//Single reverse Sorting
    student.sort(Comparator.comparing(Student:: getName).thenComparing(Student::getScore));//Double

Sort LinkedList in Java

5 Answers5