Sort ArrayList of strings by length

Question

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 special 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)

Answer 1

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).

Answer 2

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

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

Answer 3

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()));