Java Microbenchmark Harness - how to get the duration of a Benchmark?

Suppose I have

@Benchmark
@OutputTimeUnit(TimeUnit.MICROSECONDS)
public void foo() {
    for (int i = 0; i < 1000; i++) {
        System.out.println(i);
    }
}

and it runs, say, in 300 microseconds.

Question: is there any way of obtaining an int/long with the value of 300?

You can run the benchmark programatically and access its result:

public class BenchmarkRunner {

  public static void main(String[] args) throws Exception {
    Options opt = new OptionsBuilder()
            .include(YourBenchmark.class.getSimpleName())
            .warmupIterations(10)
            .warmupTime(TimeValue.seconds(1))
            .measurementIterations(10)
            .measurementTime(TimeValue.seconds(2))
            .forks(5)
            .shouldFailOnError(true)
            .build();

    Collection<RunResult> runResults = new Runner(opt).run();
    runResults.forEach(runResult -> {
      Result primaryResult = runResult.getPrimaryResult();
      double score = primaryResult.getScore(); // <-- here's the score of your benchmark
    });
  }
}