Java Data Type - 如何从持续时间创建StopWatch

import java.time.Duration;

public class StopWatch {

  private long startTime = System.nanoTime();

  public Duration time() {
    return Duration.ofNanos(System.nanoTime() - startTime);
  }

  public Duration reset() {
    long now = System.nanoTime();
    long duration = (now - startTime) / 1000000L;
    startTime = now;
    return Duration.ofNanos(duration);
  }
}