java获取集合Collection的差集,去重并集,交集(适合数据十几万以上)

集合操作直接使用remove来比较两个集合的差集,数据量达到十几万时,效率比较慢,推荐使用一下方式.

package com.lcw.adapter;

import java.util.*;

/**
 * @author: craywen
 * @date: 2021-02-22 16:07
 * @desc:
 */
public class set {
    
    
    public static void main(String args[]) {
    
    
        getList();
    }

    // 获取两个ArrayList的差集、交集、去重并集(数据量大小不限制)
    private static void getList() {
    
    
        Collection<String> firstArrayList = new ArrayList<String>();
        Collection<String> secondArrayList = new ArrayList<String>();
        Collection<String> defectList = new ArrayList<String>();//差集List
        Collection<String> collectionList = new ArrayList<String>();//交集List
        Collection<String> unionList = new ArrayList<String>();//去重并集List
        try {
    
    
            firstArrayList.add("aaa");
            firstArrayList.add("bbb");
            firstArrayList.add("ccc");
            firstArrayList.add("ddd");

            secondArrayList.add("bbb");
            secondArrayList.add("ccc");
            secondArrayList.add("eee");
            // 获取差集
            defectList = receiveDefectList(firstArrayList, secondArrayList);
            Iterator<String> defectIterator = defectList.iterator();
            System.out.println("===================差集===================");
            while(defectIterator.hasNext()) {
    
    
                System.out.println(defectIterator.next());
            }
            // 获取交集
            collectionList = receiveCollectionList(firstArrayList, secondArrayList);
            Iterator<String> collectionIterator = collectionList.iterator();
            System.out.println("===================交集===================");
            while(collectionIterator.hasNext()) {
    
    
                System.out.println(collectionIterator.next());
            }
            // 获取去重并集
            unionList = receiveUnionList(firstArrayList, secondArrayList);
            Iterator<String> unionIterator = unionList.iterator();
            System.out.println("===================去重并集===================");
            while(unionIterator.hasNext()) {
    
    
                System.out.println(unionIterator.next());
            }
        }catch(Exception e) {
    
    
            e.printStackTrace();
        }
    }

    /**
     * @方法描述：获取两个ArrayList的差集
     * @param firstArrayList 第一个Collection
     * @param secondArrayList 第二个Collection
     * @return resultList 差集Collection
     */
    public static Collection<String> receiveDefectList(Collection<String> firstArrayList, Collection<String> secondArrayList) {
    
    
        Collection<String> resultList = new ArrayList<String>();
        LinkedList<String> result = new LinkedList<String>(firstArrayList);// 大集合用linkedlist
        HashSet<String> othHash = new HashSet<String>(secondArrayList);// 小集合用hashset
        // 采用Iterator迭代器进行数据的操作
        result.removeIf(othHash::contains);
        resultList = new ArrayList<String>(result);
        return resultList;
    }

    /**
     * @方法描述：获取两个ArrayList的交集
     * @param firstArrayList 第一个Collection
     * @param secondArrayList 第二个Collection
     * @return resultList 交集Collection
     */
    public static Collection<String> receiveCollectionList(Collection<String> firstArrayList, Collection<String> secondArrayList) {
    
    
        Collection<String> resultList = new ArrayList<String>();
        LinkedList<String> result = new LinkedList<String>(firstArrayList);// 大集合用linkedlist
        HashSet<String> othHash = new HashSet<String>(secondArrayList);// 小集合用hashset
        // 采用Iterator迭代器进行数据的操作
        result.removeIf(s -> !othHash.contains(s));
        resultList = new ArrayList<String>(result);
        return resultList;
    }

    /**
     * @方法描述：获取两个ArrayList的去重并集
     * @param firstArrayList 第一个Collection
     * @param secondArrayList 第二个Collection
     * @return resultList 去重并集Collection
     */
    public static Collection<String> receiveUnionList(Collection<String> firstArrayList, Collection<String> secondArrayList) {
    
    
        Collection<String> resultList = new ArrayList<String>();
        Set<String> firstSet = new TreeSet<String>(firstArrayList);
        for(String id : secondArrayList) {
    
    
            // 当添加不成功的时候 说明firstSet中已经存在该对象
            firstSet.add(id);
        }

        resultList = new ArrayList<String>(firstSet);
        return resultList;
    }

}

转摘:https://www.cnblogs.com/o0shine0o-zp/p/6902392.html