Java streams，从2个列表中获取数据

List<Integer> list1 = Arrays.asList(1, 2, 3);
List<Integer> list2 = Arrays.asList(4, 5, 6);

Stream<Integer> combinedStream = Stream.concat(list1.stream(), list2.stream());

List<Person> list1 = Arrays.asList(new Person("Alice"), new Person("Bob"));
List<Person> list2 = Arrays.asList(new Person("Charlie"), new Person("David"));

Stream<Person> combinedStream = Stream.of(list1, list2)
        .flatMap(List::stream);

List<Integer> list1 = Arrays.asList(1, 2, 3);
List<Integer> list2 = Arrays.asList(4, 5, 6);

Stream<Integer> combinedStream = Stream.of(list1, list2)
        .flatMap(List::stream);