Java split list into list nested list method, batch processing

Background : Java often encounters the need to process a list in batches. At this time, it is a good way to divide a list into list<List> nesting.

There are three solutions : 1. You can write an ordinary foreach loop and add it to a list how many times, and then renew a list

2. Use Guava's tools

Lists.partition(要分割的list, 每个小list多少条数据)

3. Use apach's tool class commons-collections4

ListUtils.partition(要分割的list, 每个小list多少条数据)

Code demo

package formal.util.list;


import com.google.common.collect.Lists;
import org.apache.commons.collections4.ListUtils;

import java.util.ArrayList;
import java.util.List;

/**
 * @author : 
 * @date : 2019/11/2
 * @description:分批处理，分批插入 
 */
public class PartialList {

    public static void main(String[] args) {
        /*1.正常情况,使用guava工具类分类，包：com.google.common.collect.Lists*/
        List<Integer> intList1 = Lists.newArrayList(1, 2, 3, 4, 5, 6, 7, 8);
        List<List<Integer>> subs1 = Lists.partition(intList1, 3);
        PartialList.printList2(subs1);
        /*2.list为empty*/
        List<Integer> intList2 = new ArrayList<>();
        /*3.分组大于数据*/
        List<List<Integer>> subs2 = Lists.partition(intList2, 10);
        PartialList.printList2(subs2);
        System.out.println("以下是apache的工具类=================================");
        /*正常情况,使用apache工具类分类，包：com.google.common.collect.Lists*/
        List<Integer> intList1apache = Lists.newArrayList(1, 2, 3, 4, 5, 6, 7, 8);
        List<List<Integer>> subs1apache = ListUtils.partition(intList1apache, 3);
        PartialList.printList2(subs1apache);
        /*list为empty*/
        List<Integer> intList2apache = new ArrayList<>();
        /*2.分组大于数据*/
        List<List<Integer>> subs2apache = ListUtils.partition(intList2apache, 10);
        PartialList.printList2(subs2apache);
    }

    public static void printList2(List<List<Integer>> listList) {
        System.out.println("输出生成list信息：" + listList.size());
        for (List<Integer> sub : listList) {
            System.out.println("进来了");
            for (Integer integer : sub) {
                System.out.println(integer);
            }
        }
        System.out.println("================");
    }
}

Execution result :

输出生成list信息：3
进来了
1
2
3
进来了
4
5
6
进来了
7
8
================
输出生成list信息：0
================
以下是apache的工具类=================================
输出生成list信息：3
进来了
1
2
3
进来了
4
5
6
进来了
7
8
================
输出生成list信息：0
================

Attached :
1. Add jar configuration , this can be used, lower version may be possible, not guaranteed

	<dependency>
			<groupId>com.google.guava</groupId>
			<artifactId>guava</artifactId>
			<version>27.1-jre</version>
	</dependency>
    <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-collections4</artifactId>
            <version>4.0</version>
    </dependency>

2. Using this segmentation will encounter the situation that the foreach cannot be removed , see the article for details: https://blog.csdn.net/Mint6/article/details/102875278

Java split list into list nested list method, batch processing

Guess you like