how can I sort alphanumerically ignoring non alphanumeric characters?

I am reading a text file that contains lines with a mix of alphanumeric characters and non-alphanumeric characters. My guess is something like removing the non alphanumeric characters and sorting then putting them back I am not sure how to do that or if that's a good way.

Before sort:

Hello
alpha
#%Alpha
--781
hello

After sort:

--781
#%Alpha
Hello
alpha
hello

current code doing the sorting:
List<String> sortedLines = Files.lines(f.toPath()).sorted().collect(Collectors.toList());

This sorts but it is putting #%Alpha before --781 and I am not sure how to remedy this. Any help would be greatly appreciated.

You can use String#replaceAll to remove all non-alphanumeric characters when sorting.

List<String> sortedLines = Files.lines(f.toPath())
        .sorted(Comparator.comparing(s -> s.replaceAll("[^a-zA-Z0-9]", "")))
        .collect(Collectors.toList());

You can also use Collections.sort and define a custom comparator such as following :

private static List<String> sort(List<String> inputList){
	Collections.sort(inputList, (s1, s2) -> s1.replaceAll("[^a-zA-Z0-9]", "").compareTo(s2.replaceAll("[^a-bA-Z0-9]", "")));
	return inputList;
}