JAVA获取两个List的交集、差集以及并集

Dear 丶 2023-10-06 12:52 3阅读 0赞

import java.util.Set;
    import java.util.List;
    import java.util.HashSet;
    import java.util.TreeSet;
    import java.util.Iterator;
    import java.util.ArrayList;
    import java.util.LinkedList;
     
    public class getSet {
        
        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() {
            List<String> firstArrayList = new ArrayList<String>();
            List<String> secondArrayList = new ArrayList<String>();
            List<String> defectList = new ArrayList<String>();//差集List
            List<String> collectionList = new ArrayList<String>();//交集List
            List<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ArrayList
         * @param secondArrayList 第二个ArrayList
         * @return resultList 差集ArrayList
         */
        public static List<String> receiveDefectList(List<String> firstArrayList, List<String> secondArrayList) {
            List<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  
            Iterator<String> iter = result.iterator();// 采用Iterator迭代器进行数据的操作  
            while(iter.hasNext()){  
                if(othHash.contains(iter.next())){  
                    iter.remove();            
                }     
            }  
            resultList = new ArrayList<String>(result);
            return resultList;
        }
        
        /**
         * @方法描述：获取两个ArrayList的交集
         * @param firstArrayList 第一个ArrayList
         * @param secondArrayList 第二个ArrayList
         * @return resultList 交集ArrayList
         */
        public static List<String> receiveCollectionList(List<String> firstArrayList, List<String> secondArrayList) {
            List<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  
            Iterator<String> iter = result.iterator();// 采用Iterator迭代器进行数据的操作  
            while(iter.hasNext()) {
                if(!othHash.contains(iter.next())) {  
                    iter.remove();            
                }     
            }
            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ArrayList
         * @param secondArrayList 第二个ArrayList
         * @return resultList 去重并集ArrayList
         */
        public static List<String> receiveUnionList(List<String> firstArrayList, List<String> secondArrayList) {
            List<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;
        }
    }