关于java8:java8之flatMap应用

    @Test    public void testFlatMap() {        Teacher yuwen1 = Teacher.builder().teacherName("飞老师").level(1).build();        Teacher yuwen2 = Teacher.builder().teacherName("木老师").level(2).build();        Teacher shuxue1 = Teacher.builder().teacherName("算老师").level(3).build();        List<Teacher> teacherList = new ArrayList<>(Arrays.asList(yuwen1, yuwen2));        List<Teacher> teacher2List = new ArrayList<>(Arrays.asList(shuxue1));        Student zhangsan = Student.builder().name("张三").gender("男").teacherList(teacherList).build();        Student lisi = Student.builder().name("李四").gender("男").teacherList(teacherList).build();        Student wangwu = Student.builder().name("王五").gender("女").teacherList(teacher2List).build();        List<Student> students = new ArrayList<>(Arrays.asList(zhangsan, lisi, wangwu));        Set<Teacher> allStudentsTeachers = students.stream().flatMap(e -> e.getTeacherList().stream()).collect(Collectors.toSet());        allStudentsTeachers.stream().forEach(System.out::println);    }

留神是: e -> e.getTeacherList().stream()
留神 外部list还要被"化骨绵掌"击为stream!!!