如何将以下Java代码转换为Java 8？

Question

I write java code like this ,

 private DateTime getChangedDoseEndDate(final DateTime actualTerminateDate, final DateTime discontinueDate)
  {
    if (actualTerminateDate == null)
    {
      return discontinueDate;
    }

    if (discontinueDate == null)
    {
      return actualTerminateDate;
    }
    else if (actualTerminateDate.isBefore(discontinueDate))
    {
      return actualTerminateDate;
    }
    else
    {
      return discontinueDate;
    }
  }

I am trying to it convert Guava , to write single line function. This is ,I tried one. Is it correct ? I also need to it convert java 8 .

return Ordering.natural().nullsLast().min(discontinueDate, actualTerminateDate);

Answer 1

If you want to make your code more succinct, you have other means to do so, unless you want just to show off with a one-liner. Here is one of the ways to approach it. It's not a one-liner and it's not using any lambdas either, but it's still a valid Java 8 code and it has the same logic, but expressed in a more simple way.

DateTime getChangedDoseEndDate(final DateTime actualTerminateDate, final DateTime discontinueDate) {
  if (actualTerminateDate != null && actualTerminateDate.isBefore(discontinueDate)) {
    return actualTerminateDate;
  }
  return discontinueDate;
}

You can even use ternary operator and fit it in a one-liner (and it's still a valid Java 8 code).

DateTime getChangedDoseEndDate(final DateTime terminateDate, final DateTime discontinueDate) {
  return terminateDate != null && terminateDate.isBefore(discontinueDate) ? terminateDate : discontinueDate;
}

However, if you can guarantee null safety, you may have something similar to Guava's code of yours (which is working perfectly, since you asked).

DateTime getChangedDoseEndDate(@Nonnull final DateTime actualTerminateDate, @Nonnull final DateTime discontinueDate) {
  return Stream.of(actualTerminateDate, discontinueDate).min(Comparator.naturalOrder()).get();
}