Coding Problem 4: Facebook problem

Problem.java

import java.util.Comparator;
import java.util.List;

public class Problem {

    public static int productOfNumbers(List<Integer> numbers) {
        Number result = numbers.stream()
                .map(n -> new Number(Math.abs(n), n < 0))
                .sorted(Comparator.reverseOrder())
                .limit(3)
                .reduce((n1, n2) -> new Number(n1.number * n2.number, isNegative(n1, n2)))
                .get();
        return result.isNegative ? -1*result.number : result.number;
    }

    private static boolean isNegative(Number n1, Number n2) {
        if (n1.isNegative && n2.isNegative) {
            return false;
        } else return n1.isNegative || n2.isNegative;
    }

    private static class Number implements Comparable<Number> {
        int number;
        boolean isNegative;

        Number(int number, boolean negative) {
            this.number = number;
            this.isNegative = negative;
        }

        @Override
        public int compareTo(Number o) {
            return number - o.number;
        }
    }
}