What is the best way of converting List object to long[] array in java?

Since Java 8, you can do the following:

long[] result = values.stream().mapToLong(l -> l).toArray();

What’s happening here?

1. We convert the List<Long> into a Stream<Long>.
2. We call mapToLong on it to get a LongStream
   • The argument to mapToLong is a ToLongFunction, which has a long as the result type.
   • Because Java automatically unboxes a Long to a long, writing l -> l as the lambda expression works. The Long is converted to a long there. We could also be more explicit and use Long::longValue instead.
3. We call toArray, which returns a long[]