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

With Java 8 and com.google.common.collect.Lists, you can do something like:

public class BatchProcessingUtil {
    public static  List process(List data, int batchSize, Function, List> processFunction) {
        List> batches = Lists.partition(data, batchSize);
        return batches.stream()
                .map(processFunction) // Send each batch to the process function
                .flatMap(Collection::stream) // flat results to gather them in 1 stream
                .collect(Collectors.toList());
    }
}

In here T is the type of the items in the input list and U the type of the items in the output list

And You can use it like this:

List userKeys = [... list of user keys]
List users = BatchProcessingUtil.process(
    userKeys,
    10, // Batch Size
    partialKeys -> service.getUsers(partialKeys)
);