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javacollectionsguavaapi-designiterable

Why there is no getFirst(iterable) method?

Iterables present two methods for getLast 

 public static <T> T getLast(Iterable<T> iterable);
 public static <T> T getLast(Iterable<T> iterable, @Nullable T defaultValue);

but only one for getFirst

 public static <T> T getFirst(Iterable<T> iterable, @Nullable T defaultValue);

Is there are any design/implementation reason for breaking symmetry?

Solution

  • I think the point is that there is no reason for a getFirst(iterable) in that this could be done with iterable.iterator().next(). Guava makes an excellent attempt to keep the API small and so does not add things that could / should be done easily another way.

    On the other hand, there is not already a mechanism to test if an iterable is empty and if so return a default value instead of the first value. Hence, getFirst(iterable, default).

    Also, there is not a simple way to get the last element, hence getLast(iterable) and getLast(iterable, default)