Java 8 Stream with batch processing

Question

I have a large file that contains a list of items.

I would like to create a batch of items, make an HTTP request with this batch (all of the items are needed as parameters in the HTTP request). I can do it very easily with a for loop, but as Java 8 lover, I want to try writing this with Java 8's Stream framework (and reap the benefits of lazy processing).

Example:

List<String> batch = new ArrayList<>(BATCH_SIZE);
for (int i = 0; i < data.size(); i++) {
  batch.add(data.get(i));
  if (batch.size() == BATCH_SIZE) process(batch);
}

if (batch.size() > 0) process(batch);

I want to do something a long the line of lazyFileStream.group(500).map(processBatch).collect(toList())

What would be the best way to do this?

Answer 1

For completeness, here is a Guava solution.

Iterators.partition(stream.iterator(), batchSize).forEachRemaining(this::process);

In the question the collection is available so a stream isn't needed and it can be written as,

Iterables.partition(data, batchSize).forEach(this::process);