An implementation of a comparator that sort strings in an order that makes sense for a human. I.e. it performs an "alphabetical"/"alphanumeric" comparison instead of a lexicographical comparison.
It is mainly intended to be used to sort information that are to be read by humans (in UI's etc). So keep in mind that what the "correct" ordering should be is entirely subjective and application specific.
It should however be straightforward to modify the comparator to suit any specific needs.
Given file names:
image-1.jpg
image-4.jpg
image-10.jpg
image-02.jpg
image-22.jpg
image-9.jpg
image-11.jpg
A standard lexicographical sort would produce the following:
image-02.jpg
image-1.jpg
image-10.jpg
image-11.jpg
image-22.jpg
image-4.jpg
image-9.jpg
But as a human, the numbers in the file name has a meaning an the file "9" should come before the file "10", and "02" should not come before "1".
Using the AlphanumericComparator would produce the following result instead:
image-1.jpg
image-02.jpg
image-4.jpg
image-9.jpg
image-10.jpg
image-11.jpg
image-22.jpg
If we sort the strings:
Hard drive 20GB
Hard drive 2GB
A standard lexicographical sort would produce the following:
Hard drive 20GB
Hard drive 2GB
While the AlphanumericComparator would produce:
Hard drive 2GB
Hard drive 20GB
This comparator also supports the use of a locale-sensitive Collator for string comparison. This makes this comparator very flexible for sorting.
@Test
public void example() {
final List<String> stringsToSort = asList("HD 20GB", "HD 2GB");
stringsToSort.sort(new AlphanumericComparator(Locale.ENGLISH));
assertEquals(asList("HD 2GB", "HD 20GB"), stringsToSort);
}And an example of how to sort using language specific collation rules:
@Test
public void should_demonstrate_sorting_with_swedish_collation() {
final List<String> stringsToSort = asList("Ö", "Ø", "O");
stringsToSort.sort(new AlphanumericComparator(new Locale("sv", "SE")));
assertEquals(asList("O", "Ö", "Ø"), stringsToSort);
}Releases are available at the Maven central repository. Or you can just use the source code directly if you prefer that.
You can find the latest releases here: