[java] How to convert an iterator to a stream?

I am looking for a concise way to convert an Iterator to a Stream or more specifically to "view" the iterator as a stream.

For performance reason, I would like to avoid a copy of the iterator in a new list:

Iterator<String> sourceIterator = Arrays.asList("A", "B", "C").iterator();
Collection<String> copyList = new ArrayList<String>();
sourceIterator.forEachRemaining(copyList::add);
Stream<String> targetStream = copyList.stream();

Based on the some suggestions in the comments, I have also tried to use Stream.generate:

public static void main(String[] args) throws Exception {
    Iterator<String> sourceIterator = Arrays.asList("A", "B", "C").iterator();
    Stream<String> targetStream = Stream.generate(sourceIterator::next);
    targetStream.forEach(System.out::println);
}

However, I get a NoSuchElementException (since there is no invocation of hasNext)

Exception in thread "main" java.util.NoSuchElementException
    at java.util.AbstractList$Itr.next(AbstractList.java:364)
    at Main$$Lambda$1/1175962212.get(Unknown Source)
    at java.util.stream.StreamSpliterators$InfiniteSupplyingSpliterator$OfRef.tryAdvance(StreamSpliterators.java:1351)
    at java.util.Spliterator.forEachRemaining(Spliterator.java:326)
    at java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:580)
    at Main.main(Main.java:20)

I have looked at StreamSupport and Collections but I didn't find anything.

This is possible in Java 9.

Stream.generate(() -> null)
    .takeWhile(x -> iterator.hasNext())
    .map(n -> iterator.next())
    .forEach(System.out::println);

Use Collections.list(iterator).stream()...

import com.google.common.collect.Streams;

and use Streams.stream(iterator) :

Streams.stream(iterator)
       .map(v-> function(v))
       .collect(Collectors.toList());

Great suggestion! Here's my reusable take on it:

public class StreamUtils {

    public static <T> Stream<T> asStream(Iterator<T> sourceIterator) {
        return asStream(sourceIterator, false);
    }

    public static <T> Stream<T> asStream(Iterator<T> sourceIterator, boolean parallel) {
        Iterable<T> iterable = () -> sourceIterator;
        return StreamSupport.stream(iterable.spliterator(), parallel);
    }
}

And usage (make sure to statically import asStream):

List<String> aPrefixedStrings = asStream(sourceIterator)
                .filter(t -> t.startsWith("A"))
                .collect(toList());

Create Spliterator from Iterator using Spliterators class contains more than one function for creating spliterator, for example here am using spliteratorUnknownSize which is getting iterator as parameter, then create Stream using StreamSupport

Spliterator<Model> spliterator = Spliterators.spliteratorUnknownSize(
        iterator, Spliterator.NONNULL);
Stream<Model> stream = StreamSupport.stream(spliterator, false);

Since version 21, Guava library provides Streams.stream(iterator)

It does what @assylias's answer shows.

Another way to do this on Java 9+ using Stream::iterate(T, Predicate, UnaryOperator):

Stream.iterate(iterator, Iterator::hasNext, UnaryOperator.identity())
        .map(Iterator::next)
        .forEach(System.out::println);