Demonstrates the time difference between sequential streams and parallel streams.

Java8ParallelStream.java

public class Java8ParallelStream {
  public static void main(String[] args) {
        List<String> values = new ArrayList<>();
        int max = 1000000;
        for (int i = 0; i < max; i++) {
            UUID id = UUID.randomUUID();
            values.add(id.toString());
        }

        NoArgsFunction sequential = () -> values.stream().sorted().count();
        NoArgsFunction parallel = () -> values.parallelStream().sorted().count();

        time(sequential);
        time(parallel);
    }

    static void time(NoArgsFunction f) {
        long t0 = System.nanoTime();

        f.execute();

        long t1 = System.nanoTime();

        long millis = TimeUnit.NANOSECONDS.toMillis(t1 - t0);
        System.out.println(String.format("Took: %d ms", millis));
    }

    @FunctionalInterface
    private interface NoArgsFunction {
        void execute();
    }
}