Hi Rob,
On 12/10/18 11:11 PM, Rob Griffin (rgriffin) wrote:
Hi Remi,
There are certainly places where we could do this when we are simply iterating
over the results but that is not always the case. However I was disappointed to
find that the enhanced for loop can't iterate over a stream so if callers of
your example methods where doing something like this
for (Employee emp : getAllEmployee()) {
...
}
then it would have to change to a forEach call if getAllEmployee returned a
Stream.
You can also get an Iterator from a Stream, so if you need external
iteration over elements of a Stream you don't have to collect it 1st to
some Collection:
Stream<String> names() {
return Stream.of("John", "Jil", "Jack");
}
...and then...
for (String name : (Iterable<String>) names()::iterator) {
System.out.println(name);
}
This is hack-ish as it relies on the fact that enhanced for loop calls
Iterable.iterator() method only once, but is the only way to do it if
you already have a reference to Stream at hand. This would be more
correct way of doing it if you can call a factory for Stream:
for (String name : (Iterable<String>) () -> names().iterator()) {
System.out.println(name);
}
Regards, Peter
P.S. I wonder why the enhanced for loop doesn't establish a context
where the type of expression after the colon could be inferred, so no
cast would be necessary. Perhaps because that type could either be an
Iterable<T> or a T[] ?
