List requirements set union, intersection, deduplication, difference sets, etc.

List 集合的几种算法

@org.junit.Test
public void testListToCompare() {
    List<String> list1 = new ArrayList<>();
    List<String> list2 = new ArrayList<>();
    list1.add("a");
    list1.add("b");
    list1.add("c");
    list1.add("d");

    list2.add("c");
    list2.add("d");
    list2.add("e");
    list2.add("e");

    System.out.println("list1:" + list1);
    System.out.println("list2:" + list2);

    //并集
    list1.addAll(list2);
    System.out.println("并集：" + list1);

    //无重复并集
    list1.removeAll(list2);    // intersection    System.out.println ( "and no duplicate set:" List1 +);
    list1.addAll (List2);



    list1.retainAll (List2); 
    System.out.println ( "Intersection:" List1 +); 

    // difference set 
    list1.removeAll (List2); 
    System.out.println ( "difference set:" List1 +); 

    // to repeat JDK1.8 new features 
    List <String> = list2.stream List () DISTINCT () the collect (Collectors.toList ());.. 
    System.out.println ( "deduplication:" List +); 


}