Spring Batch - Using an ItemWriter with List of Lists

Question

Our processor returns a List (effectively passing a List>) to our ItemWriter.

Now, we observed t

Answer 1

public class ListUnpackingItemWriter implements FlatFileItemWriter>, ItemStream, InitializingBean {

    @Override
    public void afterPropertiesSet() {
        setLineAggregator(item -> String.join("\n", item.stream().map(T::toString).collect(Collectors.toList())));
    }

}

Just added a custom line aggregator to the above solution, this helps in writing the content to a file by using FlatFileItemWriter>. You can replace T with actual class name to avoid compilation error while calling toString() method.