Java 2 List collection data seek and complement operations

During the development process, we may need to process data from 2 or more list collections, such as multiple list collection data for the same element, and multiple list collection data to get only the data that belongs to itself, as shown:

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Here is a list of 2 lists, some of which require us to handle 3 of the situation on the graph.
* Only belongs to A
* Common Elements
* Only belongs to B

This kind of processing is not unfamiliar in mathematics, only belongs to a, equivalent to a set of B on a relative complement set, the same elements, A and B of the sum, only B, equivalent to the set of a on the relative complement of B. Having understood these concepts, let's look at how Java code is implemented and the code below

public static void Test () {    list<integer> A = new arraylist<integer> ();    A.add (1);    A.add (2);    A.add (3);    A.add (4);    list<integer> B = new arraylist<integer> ();    B.add (2);    B.add (4);    B.add (5);    B.add (6);    Collection C = new arraylist<integer> (A);    C.retainall (B);    System.out.println ("A and B-set:" + C);    B.removeall (C);    System.out.println ("A relative complement to B:" + b);    A.removeall (C);    System.out.println ("B relative complement set on a:" + a);  }

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Java 2 List collection data seek and complement operations