Why there is no getFirst(iterable) method?

java collections guava api-design iterable
Stan Kurilin picture Stan Kurilin · Dec 12, 2011 · Viewed 23.4k times · Source

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?

Answer

John B picture John B · Dec 12, 2011

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)

Related questions

UnmodifiableMap (Java Collections) vs ImmutableMap (Google)

Context I need to return a reference to a map that I'm using for a data cache, and I'd like to make sure nobody can modify their reference. Question I've seen lots of references to UnmodifiableMap and ImmutableMap online, but …

Read More
How can I generate a list or array of sequential integers in Java?

Is there a short and sweet way to generate a List<Integer>, or perhaps an Integer[] or int[], with sequential values from some start value to an end value? That is, something shorter than, but equivalent to1 the …

Read More
Combine multiple Collections into a single logical Collection?

Assume, I have a constant number of collections (e.g. 3 ArrayLists) as members of a class. Now, I want to expose all the elements to other classes so they can simply iterate over all elements (ideally, read only). I'm using …

Read More