Apex工具 | 将一个list分割成n个list

sf_wilson

已于 2023-03-23 10:41:16 修改

阅读量348

点赞数

于 2023-03-12 13:41:28 首次发布

本文链接：https://blog.csdn.net/itsme_web/article/details/129474934

版权

Salesforce Experience 专栏收录该内容

151 篇文章

订阅专栏

该代码示例展示了一个公共方法，用于将一个对象列表按照指定大小分成多个子列表。它创建了一个名为`doPartions`的方法，接受一个记录列表、分块大小和目标类型作为参数，然后使用`Partition`内部类来执行分块操作。此外，还有一个简化版的`doListPartition`方法，实现了相同的功能但更简洁。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

Questions

I am having the list . List has 28 records. I need to split the records in the list into 13 + 13 + 2 in the code. Is it possible?

Solution

public with sharing class Lists {
    public static List<List<Object>> doPartions(List<Object> records, Integer size, Type destType){
        checkNotNull(records);
        checkArgument(size > 0);
        checkNotNull(destType);
        return new Partition(records, size, destType).doPartition();
    }
    private static void checkNotNull(Object reference) {
        if (reference == null) {
            throw new NullPointerException();
        }
    }
    private static void checkArgument(Boolean expression) {
        if (!expression) {
            throw new IllegalArgumentException();
        }
    }
    private class Partition{
        private List<Object> items;
        private Integer splitSize;
        private Type destType;
        Partition(List<Object> records, Integer size, Type destType){
            this.items = records;
            this.splitSize = size;
            this.destType = destType;
        }
        List<List<Object>> doPartition(){
            List<List<Object>> result = (List<List<Object>>)destType.newInstance();
            List<Object> protoList = items.clone();
            protoList.clear();
            List<Object> tempList = protoList.clone();
            Integer index = 0, count = 0, size = items.size();
            while(index < size) {
                tempList.add(items.get(index++));
                ++count;
                if(count == splitSize) {
                    result.add(tempList);
                    tempList = protoList.clone();
                    count = 0;
                }
            }
            if(!tempList.isEmpty()) {
                result.add(tempList);
            }
            return result;
        }
    }
    public class IllegalArgumentException extends Exception {}
}

Usage

List<Integer> input = new List<Integer> {1, 2, 3, 4, 5, 6, 7};
List<List<Integer>> result = (List<List<Integer>>) Lists.doPartions(input, 2, List<List<Integer>>.class);
System.debug(result);

DEBUG|((1, 2), (3, 4), (5, 6), (7))

轻量化

public with sharing class Utility {
    /**
     * Desc: split one list into multiple list
     * Usage: List<List<Integer>> result = (List<List<Integer>>) Utility.doListPartition(new List<Integer> {1, 2, 3}, 2, List<List<Integer>>.class);
     */
    public static List<List<Object>> doListPartition(List<Object> items, Integer splitSize, Type destType) {
        if(items == null || destType == null) throw new NullPointerException();
        if (splitSize <= 0) throw new IllegalArgumentException();

        List<List<Object>> result = (List<List<Object>>)destType.newInstance();
        List<Object> protoList = items.clone();
        protoList.clear();
        List<Object> tempList = protoList.clone();
        Integer index = 0, count = 0, size = items.size();

        while(index < size) {
            tempList.add(items.get(index++));
            ++count;
            if(count == splitSize) {
                result.add(tempList);
                tempList = protoList.clone();
                count = 0;
            }
        }

        if(!tempList.isEmpty()) result.add(tempList);

        return result;
    }

    public class IllegalArgumentException extends Exception {}
}