public static void main(String[] args){
        Map<String,String> map= new HashMap<>();
        map.forEach((k,v)->{
            System.out.println(k);
            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());
        });
    }