How to implement a Java stream?

Question

I want to implement a Stream.

I don\'t want to just use implements Stream, because I would have to implement a ton of met

Answer 1

If you're wanting to make your own Stream because you want custom close() logic, the simplest solution is to create a Stream from an Iterator, and call onClose(Runnable). For instance, to stream from a Reader via Jackson:

MappingIterator values = objectMapper.reader(type).readValues(reader);
return StreamSupport
        .stream(Spliterators.spliteratorUnknownSize(values, Spliterator.ORDERED), false)
        .onClose(() -> {
            try {
                reader.close();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        });