Re: Add convenience collect methods to the Stream interface

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[] ?