使用lambda求两个集合的差集、交集、并集，去除两个集合相同的数据

淩亂°似流年 2024-03-24 15:51 113阅读 0赞

### 求两个集合的差集、交集、并集 ###

package com.ekkcole.controlle;
    
    import java.math.BigDecimal;
    import java.util.Arrays;
    import java.util.List;
    import java.util.stream.Collectors;
    
    public class Test {
        
        public static void main(String[] args) {
        
            chaJi();
            jioaJi();
            bingJi();
        }
    
    
        /**
         * 求集合差集
         */
        public static void chaJi(){
        
            List<String> listOne = Arrays.asList("1", "2", "3", "4");
            List<String> listTwo = Arrays.asList("1", "5", "6", "7");
            //保留集合2的数据，去除和集合1相同的值
            listTwo = listTwo.stream().filter(a -> {
        
                return !listOne.contains(a);
            }).collect(Collectors.toList());
            //谁在前就求谁的
            System.out.println("差集" + listTwo.toString());
        }
    
        /**
         * 求两个集合交集
         */
        public static void jioaJi(){
        
            List<String> listOne = Arrays.asList("1", "2", "3", "4");
            List<String> listTwo = Arrays.asList("1", "5", "6", "7");
            //保留集合2的数据，去除和集合1相同的值
            List<String> collect = listTwo.stream().filter(a -> {
        
                return listOne.contains(a);
            }).collect(Collectors.toList());
            System.out.println("交集 " + collect.toString());
        }
    
        /**
         *并集
         */
        public static void bingJi(){
        
            List<String> listOne = Arrays.asList("1", "2", "3", "4");
            List<String> listTwo = Arrays.asList("1", "5", "6", "7");
            //要使用新的集合不然会报错
            List<String> collect1 = listOne.parallelStream().collect(Collectors.toList());
            List<String> collect2 = listTwo.parallelStream().collect(Collectors.toList());
            //并集
            collect1.addAll(collect2);
            System.out.println("并集 = " + collect1.toString());
            //去重并集
            collect1.addAll(collect2);
            List<String> collect = collect1.stream().distinct().collect(Collectors.toList());
            System.out.println("去重并集= " + collect.toString());
        }
    
    }