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 par

Answer 1

this is a pure java solution that's evaluated lazily.

public static  Stream> partition(Stream stream, int batchSize){
    List> currentBatch = new ArrayList>(); //just to make it mutable 
    currentBatch.add(new ArrayList(batchSize));
    return Stream.concat(stream
      .sequential()                   
      .map(new Function>(){
          public List apply(T t){
              currentBatch.get(0).add(t);
              return currentBatch.get(0).size() == batchSize ? currentBatch.set(0,new ArrayList<>(batchSize)): null;
            }
      }), Stream.generate(()->currentBatch.get(0).isEmpty()?null:currentBatch.get(0))
                .limit(1)
    ).filter(Objects::nonNull);
}