2个list取交集_角的集合如何取交集

编程汇总 • 2025-05-30 23:01 • 阅读 81

两个List集合取交集、并集、差集、去重并集的一个简单Demo，可供参考：

import java.util.ArrayList;

import java.util.List;

import static java.util.stream.Collectors.toList;

public class Test { 



public static void main(String[] args) { 



List list1 = new ArrayList();

list1.add("1");

list1.add("2");

list1.add("3");

list1.add("5");

list1.add("6");

List list2 = new ArrayList();

list2.add("2");

list2.add("3");

list2.add("7");

list2.add("8");

// 交集

List intersection = list1.stream().filter(item -> list2.contains(item)).collect(toList());

System.out.println("---交集 intersection---");

intersection.parallelStream().forEach(System.out :: println);

// 差集 (list1 - list2)

List reduce1 = list1.stream().filter(item -> !list2.contains(item)).collect(toList());

System.out.println("---差集 reduce1 (list1 - list2)---");

reduce1.parallelStream().forEach(System.out :: println);

// 差集 (list2 - list1)

List reduce2 = list2.stream().filter(item -> !list1.contains(item)).collect(toList());

System.out.println("---差集 reduce2 (list2 - list1)---");

reduce2.parallelStream().forEach(System.out :: println);

// 并集

List listAll = list1.parallelStream().collect(toList());

List listAll2 = list2.parallelStream().collect(toList());

listAll.addAll(listAll2);

System.out.println("---并集 listAll---");

listAll.parallelStream().forEachOrdered(System.out :: println);

// 去重并集

List listAllDistinct = listAll.stream().distinct().collect(toList());

System.out.println("---得到去重并集 listAllDistinct---");

listAllDistinct.parallelStream().forEachOrdered(System.out :: println);

System.out.println("---原来的List1---");

list1.parallelStream().forEachOrdered(System.out :: println);

System.out.println("---原来的List2---");

list2.parallelStream().forEachOrdered(System.out :: println);

}

}

private static  Predicate distinctByKey(Function keyExtractor) { 



Map seen = new ConcurrentHashMap<>();

return t -> seen.putIfAbsent(keyExtractor.apply(t), Boolean.TRUE) == null;

}

public static void main(String[] args) { 



List list=new ArrayList<>();

list.add(1);

list.add(2);

list.add(3);

list.add(4);

List list2=new ArrayList<>();

list.add(1);

list.add(6);

list.add(6);

list.add(7);

list.addAll(list2);

list = list.stream().filter(distinctByKey(Integer::intValue)).collect(Collectors.toList());

System.out.println(list);

}

2个list取交集_角的集合如何取交集

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