java8特性-list集合根据多个字段去重

//按专业和年级去重，专业和年纪一样时表示重复对象

List<Class> distinctClass = classList.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(o -> o.getProfessionId() + ";" + o.getGrade()))), ArrayList::new));