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mars-tool 工具包 https://github.com/fashionbrot/mars-tool

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package com.github.fashionbrot.tool;

import lombok.extern.slf4j.Slf4j;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;

@Slf4j
public class ListUtil {

    public static  List deepCopy(List src)  {
        try {
            ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
            ObjectOutputStream out = new ObjectOutputStream(byteOut);
            out.writeObject(src);

            ByteArrayInputStream byteIn = new ByteArrayInputStream(byteOut.toByteArray());
            ObjectInputStream in = new ObjectInputStream(byteIn);
            @SuppressWarnings("unchecked")
            List dest = (List) in.readObject();
            return dest;
        }catch (Exception e){
            log.error("deepCopy error",e);
        }
        return  null;
    }

    public static void swapList(List list){
        if (ObjectUtil.isNotEmpty(list)){
            for (int i = 0; i < list.size()-1; i++) {
                Collections.swap(list,i,i+1);
            }
        }
    }

    public static  List getDuplicateElements(List list) {
        return list.stream() // list 对应的 Stream
                .collect(Collectors.toMap(e -> e, e -> 1, (a, b) -> a + b)) // 获得元素出现频率的 Map，键为元素，值为元素出现的次数
                .entrySet().stream() // 所有 entry 对应的 Stream
                .filter(entry -> entry.getValue() > 1) // 过滤出元素出现次数大于 1 的 entry
                .map(entry -> entry.getKey()) // 获得 entry 的键（重复元素）对应的 Stream
                .collect(Collectors.toList());  // 转化为 List
    }

}