java8 集合的交集、并集、差集

川长思鸟来 2023-03-13 15:22 0阅读 0赞

转载自[https://cloud.tencent.com/developer/article/1446248][https_cloud.tencent.com_developer_article_1446248]  
java8 集合的交集、并集、差集

import java.util.ArrayList;
    import java.util.List;
    import java.util.stream.Collectors;
    public class ArrayListDemo2 { 
    	public static void main(String[] args) { 
    		List<String> list1 = new ArrayList<String>();
    		list1.add("1");
    		list1.add("2");
    		list1.add("3");
    		list1.add("5");
    		list1.add("6");
    		list1.add("7");
    		list1.add("8");
    
    		List<String> list2 = new ArrayList<String>();
    		list2.add("2");
    		list2.add("7");
    		list2.add("10");
    		//交集
    		List<String> collect1 = list1.stream().filter(num -> list2.contains(num))
    			.collect(Collectors.toList());
    		System.out.println("交集");
    		collect1.stream().forEach(System.out::println);
    
    
    		//差集 list1-list2
    		List<String> collect2 = list1.stream().filter(num -> !list2.contains(num))
    			.collect(Collectors.toList());
    		System.out.println("差集list1-list2");
    		collect2.stream().forEach(System.out::println);
    
    		//差集list2-list1
    		List<String> collect3 = list2.stream().filter(num -> !list1.contains(num))
    			.collect(Collectors.toList());
    		System.out.println("差集list2-list1");
    		collect3.stream().forEach(System.out::println);
    
    		//并集 不去重
    		list1.addAll(list2);
    		System.out.println("并集 不去重");
    		list1.stream().forEach(System.out::println);
    
    		//并集 去重
    		List<String> collect4 = list1.stream().distinct().collect(Collectors.toList());
    		System.out.println("并集 去重");
    		collect4.stream().forEach(System.out::println);
    	}
    }

打印出来的结果是

交集
    2
    7
    差集list1-list2
    1
    3
    5
    6
    8
    差集list2-list1
    10
    并集  不去重
    1
    2
    3
    5
    6
    7
    8
    2
    7
    10
    并集  去重
    1
    2
    3
    5
    6
    7
    8
    10

[https_cloud.tencent.com_developer_article_1446248]: https://cloud.tencent.com/developer/article/1446248