public static void main(String[] args){

        Map<String,String> map= new HashMap<>();

        map.forEach((k,v)->{

            // 打印键

            System.out.println(k);

            // 打印值

            System.out.println(v);

        });

        List<Stu> list = new ArrayList();

        list.forEach((l)->{

            System.out.println(l.getId());

            System.out.println(l.getName());

        });

        Set<Stu> set = new HashSet<>();

        set.forEach((s)->{

            System.out.println(s.getId());

            System.out.println(s.getName());

        });

    }