Refactor of advent day 1 code

Main.java

package com.nerdnetworks;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.atomic.AtomicInteger;

public class Main {

    public static void main(String[] args) throws IOException {
        // Use of streams and closure below requires final variables.
        // Use Atomic* objects for accumulator-type objects.
        final AtomicInteger startingFreq = new AtomicInteger();
        // The value in the map was never used, so a set is more straightforward.
        final Set<Integer>  foundFreqs   = new HashSet<>();

        // Line below reads lines from file, converts each line to an integer, and iterates over them, all in one step.
        Files.readAllLines(Paths.get("/Users/rherrick/Development/Reference/Gradle/advent/data/day-1-input.txt")).stream().mapToInt(Integer::parseInt).forEach(value -> {
            // Parsing the file lines was basically to get the '+' or '-' at the beginning to decide whether to add or
            // subtract the absolute value of the number. This just adds the number directly and lets the sign decide
            // the operation. The return value gives you what you got from that exchange of startingFreq and endingFreq.
            final int found = startingFreq.addAndGet(value);
            if (foundFreqs.contains(found)) {
                System.out.println("Repeated frequency: " + found);
            } else {
                foundFreqs.add(found);
            }
        });

        // Result has accumulated in the startingFreq object.
        System.out.println(startingFreq.get());
    }
}