Sending duplicate to heaven with Java 8 Follow up to Duplicate like a weapon, arrays like heaven. 

@rolfl suggested in chat that I try to complete this challenge again in a Java 8 friendly way. I took the opportunity to also employ the algorithm suggested in this brilliant answer.

I'm not familiar with Java 8 features, but am definitely interested in using it more and finding the best ways to implement it.

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.util.Arrays;

public class ArrayAbsurdityJava8 {
    public static void main(String[] args) throws IOException {
        Files.lines(new File(args[0]).toPath())
                .filter(s -&gt; !s.isEmpty())
                .forEach(ArrayAbsurdityJava8::printDuplicate);
    }

    private static void printDuplicate(String line) {
        int length = Integer.parseInt(line.split(";")[0]);
        int total = Arrays.stream(line.split(";")[1].split(","))
                .mapToInt(Integer::parseInt)
                .sum();

        System.out.println(total - (length - 1) * (length - 2) / 2);
    }
}


This ended up shorter than I expected. Is this best? I was thinking of doing it my way as well, but the boolean comparison requires a for loop (am I wrong?).
line.split(";") is being called twice, so you can assign it to a variable to remove one of the calls.

Since we know there's only one ; per line, we can use indexOf to find it, and substring to extract the relevant parts of the string. This may be a little bit faster than calling split(";").