java8两个List集合取交集、并集、差集、去重并集

、、、 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<String> list1 = new ArrayList<String>();
    list1.add("1");
	list1.add("2");
	list1.add("3");
	list1.add("5");
	list1.add("6");

    List<String> list2 = new ArrayList<String>();
    list2.add("2");
	list2.add("3");
	list2.add("7");
	list2.add("8");

    // 交集
    List<String> 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<String> 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<String> 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<String> listAll = list1.parallelStream().collect(toList());
    List<String> 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<String> 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);

}
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} 、、、