Sort ArrayList of strings by length

I want to order an ArrayList of strings by length, but not just in numeric order.

Say for example, the list contains these words:

cucumber
aeronomical
bacon
tea
telescopic
fantasmagorical

They need to be ordered by their difference in length to a speci开发者_运维技巧al string, for example:

intelligent

So the final list would look like this (difference in brackets):

aeronomical     (0)
telescopic      (1)
fantasmagorical (3) - give priority to positive differences? doesn't really matter
cucumber        (3)
bacon           (6)
tea             (8)

---

Use a custom comparator:

public class MyComparator implements java.util.Comparator<String> {

    private int referenceLength;

    public MyComparator(String reference) {
        super();
        this.referenceLength = reference.length();
    }

    public int compare(String s1, String s2) {
        int dist1 = Math.abs(s1.length() - referenceLength);
        int dist2 = Math.abs(s2.length() - referenceLength);

        return dist1 - dist2;
    }
}

Then sort the list using java.util.Collections.sort(List, Comparator).

---

If you are using java 8 you can also try using this lambda

packages.sort(Comparator.comparingInt(String::length));

---

If you're using Java 8+ you can use a lambda expression to implement (@Barend's answer as) the comparator

List<String> strings = Arrays.asList(new String[] {"cucumber","aeronomical","bacon","tea","telescopic","fantasmagorical"});
strings.sort((s1, s2) -> Math.abs(s1.length() - "intelligent".length()) - Math.abs(s2.length() - "intelligent".length()));

---

• String in Ascending order

class StringLengthListSort implements Comparator<String>{

    @Override
    public int compare(String s1, String s2) {
    return s1.length() - s2.length();
    }

    /**
     * @param args
     */
    public static void main(String[] args) {
    List<String> list = new ArrayList<String>();
    StringLengthListSort ss = new StringLengthListSort();
    list.add("ram");
    list.add("rahim");
    list.add("ramshyam");
    Collections.sort(list, ss);
    System.out.println(list);
    }

}

---

You'd do this with the version of Collections.sort() that takes an explicit Comparator.

---

I have a similar problem solved by lambda expression:

listBeforeSorting.sort((s1, s2) -> s1.length() - s2.length());

This way, we will get sorted-by-length(ascending order) list.

---

Collections.sort(list, (a, b)->Integer.compare(a.length(), b.length()));

---

The use of a custom comparator is correct. This is one way to implement it:

    Comparator c = new Comparator<String>()
    {
        public int compare(String s1, String s2) {
            return Integer.compare(s1.length(), s2.length());
        }
    };
    Collections.sort(results, c);
    return results;

---

simple with Java8 solution with Comparator and Method reference only: Stream.of(list).flatMap(Collection::stream).sorted( Comparator.comparing( String::length)).collect(toList());

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The shortest code for this-

public static void main(String... str) {
        List.of("am", "I", "Best", "the").stream().sorted((a, b) -> a.length() - b.length())
                .forEach(System.out::println);
    }

---

List<String> list = Arrays.asList("geeksforgeeks", "geeksfor", "geeks");
Collections.sort(list, new Comparator<String>(){
       public int compare(String s1, String s2){
                return s1.length() - s2.length();
       }
});

---

if you are using Kotlin you can use this code

    var A = ArrayList<String>()
    A.add("Alen")
    A.add("Nymar")
    A.add("Ronaldo")
    A.add("Totianas")
    A.add("Ted")
    A.add("Sara")

    Collections.sort(A, object : Comparator<String?> {
        override fun compare(p0: String?, p1: String?): Int {
            return (p1!!.length - p0!!.length)
        }
    })

    System.out.println(A)