java 按照固定大小分割 list 集合的几种方式

1、构建一个lis集合类

    private static List<Integer> lists = new ArrayList<Integer>();

    @Before
    public void test0() {
        for (int i = 0; i <= 101; i++) {
            lists.add(i);
        }
    }

2、使用google guava工具类

    @Test
    public void test1() {
        List<List<Integer>> partitions = Lists.partition(lists, 10);
        for (List<Integer> list : partitions) {
            System.out.println(list);
        }
    }

pom.xml文件

<dependency>
    <groupId>com.google.guava</groupId>
    <artifactId>guava</artifactId>
    <version>27.1-jre</version>
</dependency>

3、使用apache collection工具类

    @Test
    public void test2() {
        List<List<Integer>> partitions = ListUtils.partition(lists, 10);
        for (List<Integer> list : partitions) {
            System.out.println(list);
        }
    }

pom.xml文件

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-collections4</artifactId>
    <version>4.3</version>
</dependency>

3、使用java8 stream分割

    @Test
    public void test3() {
        // 方法一：
        List<List<Integer>> partitions = partition(lists, 10);
        for (List<Integer> list : partitions) {
            System.out.println(list);
        }
        // 方法二：
        List<List<Integer>> partitions3 = partition3(lists, 10);
        for (List<Integer> list : partitions3) {
            System.out.println(list);
        }
    }

    // 使用流遍历操作
    private static <T> List<List<T>> partition(final List<T> list, final int size) {
        Integer limit = (list.size() + size - 1) / size;
        List<List<T>> mglist = new ArrayList<List<T>>();
        Stream.iterate(0, n -> n + 1).limit(limit).forEach(i -> {
            mglist.add(list.stream().skip(i * size).limit(size).collect(Collectors.toList()));
        });
        return mglist;
    }

    // 使用并行流处理
    private static <T> List<List<T>> partition3(final List<T> list, final int size) {
        Integer limit = (list.size() + size - 1) / size;
        List<List<T>> splitList = Stream.iterate(0, n -> n + 1).limit(limit).parallel()
            .map(a -> list.stream().skip(a * size).limit(size).parallel().collect(Collectors.toList()))
            .collect(Collectors.toList());
        return splitList;
    }

4、使用纯java手写

    @Test
    public void test4() {
        List<List<Integer>> partitions = partitions(lists, 10);
        for (List<Integer> list : partitions) {
            System.out.println(list);
        }
    }

    private static <T> List<List<T>> partitions(final List<T> list, final int size) {
        List<List<T>> result = new ArrayList<List<T>>();
        final int listSize = list.size();
        for (int i = 0; i < listSize; i += size) {
            List<T> subList = null;
            if (i + size > listSize) {
                subList = list.subList(i, i + listSize - i);
            } else {
                subList = list.subList(i, i + size);
            }
            result.add(subList);
        }
        return result;
    }