Comparing run times of computing a max int using a loop, Java 8 streams and parallel streams

StreamMax.java

package com.tobilehman.benchmarks;

import java.util.LinkedList;
import java.util.List;
import java.util.Random;

public class StreamMax {
    public static void main(String args[]) {
        StreamMax sm = new StreamMax(10_000_000);
        Long then,now;
        Integer max;

        then = System.currentTimeMillis();
        max = sm.maxByLoop();
        now = System.currentTimeMillis();
        display(max, now-then);

        then = System.currentTimeMillis();
        max = sm.maxByStream();
        now = System.currentTimeMillis();
        display(max, now-then);

        then = System.currentTimeMillis();
        max = sm.maxByParallelStream();
        now = System.currentTimeMillis();
        display(max, now-then);
    }

    private static void display(Integer max, Long interval) {
        System.out.printf("Found max = %d in %d milliseconds\n", max, interval);
    }

    private final int size;
    private final List<Integer> numbers;
    private void initNumbers() {
        if(numbers.size() == 0) {
            Random r = new Random();
            for (int i = 0; i < size; i++) {
                numbers.add(r.nextInt());
            }
        }
    }
    public StreamMax(int size) {
        this.size = size;
        this.numbers = new LinkedList<Integer>();
        initNumbers();
    }

    public Integer maxByStream() {
        return numbers.stream().max(Integer::compareTo).get();
    }

    public Integer maxByParallelStream() {
        return numbers.parallelStream().max(Integer::compareTo).get();
    }

    public Integer maxByLoop() {
        Integer max = Integer.MIN_VALUE;
        for (Integer number : numbers) {
            if(number > max) {
                max = number;
            }
        }
        return max;
    }
}