Java使用线程池对list进行分组处理

@Slf4j
public class Demo24 {
    public static void main(String[] args) {
        ArrayList list = new ArrayList<>();
        for (int i = 0; i < 1000; i++) {
            list.add("第" + i + "个");
        }

        int nThreads = 5;

        int size = list.size();
        ExecutorService executorService = Executors.newFixedThreadPool(nThreads);
        ArrayList> futures = new ArrayList<>(nThreads);

        for (int i = 0; i < nThreads; i++) {
            List list1 = list.subList(size / nThreads * i, size / nThreads * (i + 1));

            int finalI = i + 1;
            Callable task1 = () -> {
                for (String str : list1) {
                    log.info("线程{}正在处理{}", finalI, str);
                }
                return 1;
            };

            futures.add(executorService.submit(task1));
        }

        executorService.shutdown();

        if (!futures.isEmpty() && futures != null){
            log.info("end");
        }

    }
}