newStreamsCollectorsSimpleCase.java

public void newStreamsCollectorsSimpleCase() throws Exception {
    // Java 8:
    List<Student> students = getGroupStream()
            .flatMap( gr -> gr.getStudents().stream() )
            .filter( student -> student.getAverageMark() > 10L )
            .collect( Collectors.toList() );

    assertThat( students ).hasSize( 3 );

    // new Java 9 Collectors#filtering collector:
    students = getGroupStream()
            .flatMap( gr -> gr.getStudents().stream() )
            .collect( Collectors.filtering( student -> student.getAverageMark() > 10L, Collectors.toList() ) );

    assertThat( students ).hasSize( 3 );

    // Java 9 collecting right away without other operations:
    students = getGroupStream()
            .collect(
                    Collectors.flatMapping(
                            gr -> gr.getStudents().stream(),
                            Collectors.filtering(
                                    student -> student.getAverageMark() > 10L,
                                    Collectors.toList()
                            )
                    )
            );

    assertThat( students ).hasSize( 3 );
}